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Table of Contents

PagesUnit 1- Matter and Change............................................................................1 - 12

Unit 2- Atomic Theory and Structure............................................................13 - 33

Unit 3- Electrons and Periodicity...................................................................34 - 52

Unit 4- Bonding.............................................................................................53 - 67

Unit 5- Nomenclature....................................................................................68 - 87

Unit 6- Chemical Reactions...........................................................................88 - 101

Unit 7- Stoichiometry....................................................................................102 - 114

Unit 8- Gas Laws...........................................................................................115 - 132

Unit 9- Solids, Liquids and Phase Changes...................................................133 - 144

Unit 10- Solutions and Solubility..................................................................145 - 156

Unit 11- Acids and Bases...............................................................................157 - 174

Unit 12- Kinetics and Thermochemistry........................................................175 - 193

Unit 13- Oxidation and Reduction.................................................................194 - 203

Unit 1- Matter and Change

CHEMISTRY: THE STUDY OF MATTER

Chemistry is the science that investigates and explains the structure and properties of

________________. This includes its composition, properties and the changes it undergoes.

SCIENTIFIC METHOD

A scientific method is a systematic approach to answer a ______________________ or study a

situation. It starts with _____________________ - noting and recording facts. A

_________________________ is a possible explanation for what has been observed. It is an

educated _________________ as to the cause of the problem or answer to the question. An

experiment is a set of controlled observations that _____________ a hypothesis. The variable

that is changed in an experiment is called the ________________________ variable. The

variable that you watch to see how it _________________ as a result of your changes to the

independent variable is called the dependent variable. The cycle (hypothesis followed by

experimentation) repeats many times, and the hypothesis gets more and more certain. The

hypothesis becomes a _______________________, which is a thoroughly tested model that

explains why things behave a certain way. Theories can never be ____________________; they

are always subject to additional research. Another outcome is that certain behavior is repeated

many times. A scientific ____________ describes a relationship in nature that is supported by

many experiments and for which no exception has been found.

Identify the dependent variable and the independent variable in the following experiments.

a) A student tests the ability of a given chemical to dissolve in water at three different

temperatures. independent variable: _________________________________

dependent variable: _________________________________

b) A farmer compares how his crops grow with and without phosphorous fertilizers.

independent variable: _________________________________

dependent variable: _________________________________

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MATTER

Matter is anything that takes up __________________ and has mass. ______________ is the

measure of the amount of matter that an object contains. Virtually all of the matter around us

consists of mixtures. A mixture can be defined as something that has _____________________

composition. Soda is a mixture (carbon dioxide is dissolved in it), and ____________________

is a mixture (it can be strong, weak or bitter). If matter is not uniform throughout, then it is a

_______________________ mixture. If matter is uniform throughout, it is homogeneous.

Homogeneous mixtures are called ___________________. A heterogeneous mixture contains

regions that have ____________________ properties from those of other regions. When we

pour sand into water, the resulting mixture contains two distinct regions. ___________________

pavement, which has small rocks mixed with tarry goo, is a simple example of a heterogeneous

mixture. Oil-and-vinegar salad dressing, which has a layer of oil floating on a layer of vinegar,

is another example. Homogeneous mixtures (also known as solutions) are mixtures in which the

composition is _______________________, there are no chunks or layers. Salt water,

___________________ ___________________ and dust free air (mixture of nitrogen, oxygen,

argon, carbon dioxide, water vapor and other gases) are examples of homogeneous mixtures.

Brass (solid mixture of copper and ______________) is also a homogeneous mixture. Brass is

a(n) _________________, which is a mixture of metals. Since heterogeneous mixtures contain

chunks or layers, they are often easier to separate than homogeneous mixtures. A mixture of

solid particles in a liquid can be separated by pouring the mixture through a

___________________ that traps the solid particles while the liquid passes through in a process

called filtering. Some simple methods also exist for separating homogeneous mixtures. A solid

dissolved in a liquid solution can be separated by letting it dry out in the process of

___________________. Mixtures are separated into pure _____________________. A pure

substance always has the same composition. Pure substances are either elements or

_________________________. Elements are substances that cannot be broken down into other

substances chemically or _______________________. Examples include sodium, carbon and

aluminum. Compounds are substances made of two or more ______________________

combined chemically. Compounds have properties ___________________________ from those

of the original elements. Examples of compounds include water (hydrogen and oxygen) and

table salt (sodium and chlorine).

2


Classify each of the following as a pure substance, a homogeneous mixture or a heterogeneous

mixture.

A. gasoline ____________________ B. copper metal ____________________

C. a stream with gravel at the bottom ____________________

D. maple syrup _________________ E. chunky peanut butter _____________

F. common salt ____________________ G. margarine ____________________

H. a Spanish omelet ________________ I. a multivitamin tablet ________________

J. oxygen gas ____________________ K. carbon dioxide gas _________________

PROPERTIES

The properties of matter describe the characteristics and behavior of matter, including the

changes that matter undergoes. _____________________ properties are characteristics that a

sample of matter exhibits without any change in its identity. This property can be observed and

measured without _____________________ the substance.

Examples of the physical properties of a chunk of matter include its:

1. __________________________________ 2. _________________________________

3. __________________________________ 4. _________________________________

5. __________________________________ 6. _________________________________

7. __________________________________

Chemical properties are those that can be observed only when there is a change in the

___________________________ of the substance. Rusting is a chemical reaction in which iron

combines with __________________ to form a new substance, iron (III) oxide.

Classify each of the following as a chemical or physical property.

density ___________________________ reactivity ___________________________

color _____________________________ melting point ________________________

Using the Chemistry Reference Tables, which substance has a

A. density = 19.31 g/cm3 _____________________

B. melting point = -119°C _____________________

C. boiling point = 65°C _____________________

D. melting point = -73°C _____________________

3


Using the Chemistry Reference Tables, are the following substances soluble or insoluble in

water? A. zinc nitrate _____________________

B. sodium sulfate _____________________

C. calcium carbonate _____________________

D. potassium oxide _____________________

E. lead (II) fluoride _____________________

F. barium hydroxide _____________________

G. copper (II) sulfide _____________________

H. silver chloride _____________________

CHANGES

A physical change is a change in matter that does not involve a change in the chemical identity

of individual substances. The matter only changes in appearance. Examples: ______________,

_________________, __________________, _________________, ___________________, and

_____________________. A chemical property always relates to a chemical change, the change

of one or more substances _____________ other substances. Another term for chemical change

is chemical ___________________. Indications of a chemical reaction: __________________

absorbed or released, _________________ change, formation of a precipitate - ______________

that separates from solution, and formation of a ___________. All matter is made of atoms, and

any chemical change involves only a rearrangement of the atoms. Atoms do not just appear.

Atoms do not just disappear. This is an example of the law of conservation of mass (or matter),

which says that in a chemical change, matter is neither ________________ nor destroyed. All

chemical changes also involve some sort of energy change. Energy is either taken in or

__________________ ____________ as the chemical change takes place. Energy is the capacity

to do _________________. Work is done whenever something is moved. Chemical reactions

that give off heat energy are called ____________________ reactions. Chemical reactions that

_________________ heat energy are called endothermic reactions. Freezing, condensation and

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___________________ are exothermic. Melting, _______________________ and sublimation

are endothermic.

State whether each of the following is an endothermic or exothermic process.

1. melting of ice __________________________

2. combustion of gasoline __________________________

3. Natural gas is burned in a furnace. __________________________

4. When solid potassium bromide is dissolved in water, the solution gets colder.

__________________________

5. When concentrated sulfuric acid is added to water, the solution gets very hot.

__________________________

In an endothermic graph, the ____________________ have greater energy than the reactants.

The change in energy is a ______________________ value. In a(n) ____________________

graph, the reactants have greater energy than the products. The change in ________________ is

a negative value.

Sketch endothermic and exothermic graphs below. Label the reactants, products and activation energy.

Endothermic Exothermic

Conservation of Energy: Energy can be neither created nor destroyed in ordinary changes (not

nuclear); it can only change _______________.

5

Energy

Reaction Progress

Energy

Reaction Progress


6


DENSITY

Density is the amount of matter (mass) contained in a unit of ___________________.

Styrofoam has a low density or small mass per unit of volume.

Solve the following density problems.

1. The density of sugar is 1.59 g/cm3. Calculate the mass of sugar in 15.0 ml. (1 mL = 1 cm3).

2. The density of helium is 0.178 g/L. Calculate the volume of helium that has a mass of 23.5 g.

3. A 14.95 g sample of gold has a volume of 0.774 cm3. Calculate the density of gold.

4. Balsa wood has a density of 0.12 g/cm3. What is the mass of a sample of balsa wood if its volume is 134 cm3?

5. The density of ice at 0°C is 0.917 g/cm3. Calculate the volume of 145 g of ice.

6. The density of a sample of lead is found by the process of water displacement. A graduated cylinder is filled with water to the 30.0 mL mark. The cylinder with the water is placed on an electronic balance and weighs 106.82 g. A piece of lead is added to the cylinder. The cylinder is reweighed with the water and the lead and the scale reads 155.83 g. The volume of all the material in the cylinder is 34.5 mL. Calculate the density of the lead.

7. The density of an unknown solid was found by the process of water displacement. The object was massed on an electronic balance. The balance reads 125 g. 50.0 cm3 of water was poured into a 100.0 mL graduated cylinder. The unknown sample was then gently placed into the graduated cylinder. The volume in the cylinder rose to 60.7 cm3. Calculate the density of the unknown solid.

Practice / HomeworkReference Packet Study

Density: Identify the substance based on the density value given D = m / V

1. D = 0.66g/cm3

2. D = 2.702g/cm3

3. M = 20 g, V = 4.44 cm3

4. M = 3 g, V = 2.1 L

7


Melting and Boiling points: Identify the substance based on the given temperature value.

5. Melting point = 801oC

6. Boiling point = 79oC

7. Melting point = 1455oC

8. Boiling point = 1413oC

Solubility: Identify if the substance is soluble or insoluble.

9. Lithium sulfate

10. Strontium oxide

11. Lead (IV) bromide

12. Ammonium carbonate

Identify each of the following as an element, a compound, a homogeneous mixture or a

heterogeneous mixture.

13. Water

14. Cheerios in milk

15. Apple juice

16. Silver

17. Salsa

18. A bag of nuts and bolts

Identify each of the following as a chemical or physical property

19. Combustible

20. Mass

21. Volume

22. Ability to rust

Identify each of the following as a chemical or physical change

23. Melts

24. Burns

25. Dissolves

26. Rips

27. Tarnishes

28. Shatters

8


Density Practice: Solve each problem below, writing the equation and showing the substitution. Provide a unit for each answer.

1. A block of aluminum occupies a volume of 15.0 mL and weighs 40.5 g. What is its density?

2. Find the mass of gold that occupies 965 cm3 of space.

3. Mercury metal is poured into a graduated cylinder that holds exactly 22.5 mL. The mercury used to fill the cylinder weighs 306.0 g. From this information, calculate the density of mercury.

4. Find the volume occupied by 250.0 g of O2.

5. A cube of metal has a side length of 1.55 cm. If the sample is found to have a mass of 26.7 g, find the density and identity of the metal.

6. An irregularly-shaped sample of aluminum (Al) is put on a balance and found to have a mass of 43.6 g. The student decides to use the water-displacement method to find the volume. The initial volume reading is 25.5 mL and, after the Al sample is added, the water level has risen to 41.7 mL. Find the density of the Al sample in g/cm3. (Remember: 1 mL = 1 cm3.)

7. If you are sure that a sample of material is aluminum but have no measuring instruments AND are not allowed to handle the sample, how would you determine the sample’s density?

8. A gas has a mass of 7914 g and takes up enough space to fill a room that is 2.00 m X 2.00 m X 2.50 m. Determine the density of the gas in g/m3.

9. A flask that weighs 345.8 g is filled with 225 mL of carbon tetrachloride. The weight of the flask and carbon tetrachloride is found to be 703.55 g. From this information, calculate the density of carbon tetrachloride.

9


The Study of Matter Practice Test

Directions: Define and/or describe the following terms relating to the scientific method.

1. Dependent Variable _________________________________________________

2. Hypothesis __________________________________________________________

Directions: Indicate if the process listed is a physical or chemical change.

3. Food digests _________________________________________________________

4. Bending a piece of copper wire. _______________________________________

5. Two clear liquids react to form a yellow clumps ___________________________

Directions: Solve the following problems. Show all work! Be sure to include the correct unit with your final answer.6. What is the density of a substance that has a volume of 2.8cm3 and mass of 25grams?

7. What is the density of a solid that has a volume of 4 cm3 and a mass of 6 grams?

Directions: For each sample of matter below, correctly classify it as a pure substance or a mixture. 8. Trail Mix ____________________

9. Helium ____________________

Directions: For each, correctly classify as homogeneous or heterogeneous mixture.

10. Vegetable soup . ______________________

11. Gatorade . ______________________

12. Orange juice, with pulp . ______________________

Multiple Choice Practice

13. The amount of mass per unit volume refers to thea. Densityb. Specific weight

c. Volumed. Weight

14. A substance that can be further simplified may be eithera. An element or a compoundb. An element or a mixture

c. A mixture or a compoundd. A mixture or an atom

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15. A substance composed of two or more elements chemically united is calleda. An isotopeb. A compound

c. An elementd. A mixture

16. An example of a chemical change is thea. Breaking of a glass bottleb. Sawing of a piece of wood

c. Rusting of irond. Melting of an ice cube

17. A substance that cannot be further decomposed by ordinary chemical means isa. Waterb. Air

c. Sugard. Silver

18. An example of a physical change is a. The fermenting of sugar to alcoholb. The rusting of ironc. The burning of paperd. A solution of sugar in water

19. The property of matter that is independent of its surroundings and position isa. Volumeb. Density

c. Massd. Weight

e. State

20. What Kelvin temperature is equal to 25°C?a. 248 K b. 298 K

c. 100 K d. 200 K

21. Which substance cannot be decomposed into simpler substances?a. ammonia b. aluminum

c. methane d. methanol

22. A compound differs from a mixture in that a compound always has aa. homogeneous composition b. maximum of two components c. minimum of three components d. heterogeneous composition

23. Which statement describes a chemical property?a. Its crystals are a metallic gray. b. It dissolves in alcohol. c. It forms a violet-colored gas. d. It reacts with hydrogen to form a gas.

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24. To determine the density of an irregularly shaped object, a student immersed the object in 21.2 milliliters of H2O in a graduated cylinder, causing the level of the H2O to rise to 27.8 milliliters. If the object had a mass of 22.4 grams, what was the density of the object.

a. 27.8 g / mL

b. 6.6 g / mL

c. 3.0 g / mL

d. 3.4 g/ mL

25. Sarah designed an experiment to find out which mouthwash was most effective against some bacteria. She cut out four different circles from a paper towel and soaked each circle in a different mouthwash. She put the circles on a nutrient agar-coated Petri dish that was covered with bacteria commonly found in the mouth. She then incubated the plate for 24 hours. The picture shows the results of this test. Which of the following should Sarah do to improve her experiment?

a. Use different kinds of bacteria

b. Use the same type of mouthwash on each paper circle.

c. Use the same size paper circles for all mouthwashes.

d. Use a smaller Petri dish.

26. A student decided to set up an experiment to see if cats prefered skim milk or 2%milk. She put out a cup of milk for 5 kittens and then measured how much the kittens drank over the course of a day. The same kittens were used and the milk was served at the same temperature. The student discovered that the cats liked the 2% more than the skim milk. What is wrong with the above experiment?

a. Repeated experimentation is needed.

b. The milk should be served at different temperatures.

c. There are no constants present.

d. There is no independent variable.

27. An experiment for a new asthma medication was set up into two groups. Group one was given the new drug for asthma, while group 2 was given a sugar pill. The sugar pill serves as

a. Control

b. Constant

c. experimental variable

d. dependent variable

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28. A scientist plants two rows of corn for experimentation. She puts fertilizer on row 1 but does not put fertilizer on row 2. Both rows receive the same amount of water and light intensity. She checks the growth of the corn over the course of 5 months. What is a constant in this experiment?

a. Plant height

b. Corn without fertilizer

c. Corn with fertilizer

d. Amount of water

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29. Which sentence best states the importance of using control groups?a. Control groups eliminate the need for large sample sizes, reducing the number of

measurements needed.

b. Control groups eliminate the need for statistical tests and simplify calculations.

c. Control groups provide a method by which statistical variability can be reduced.

d. Control groups allow comparison between subjects receiving a treatment and those receiving no treatment

30. The measurable factor in an experiment is known as the:a. Control

b. independent variable

c. constant

d. dependent variable

31. A student decides to set up an experiment to see if detergent affects the growth of seeds. He sets up 10 seed pots. 5 of the seed pots will receive a small amount of detergent in the soil and will be placed in the sun. The other 5 seed pots will not receive detergent and will be placed in the shade. All 10 seed pots will receive the same amount of water, the same number of seeds, and the same type of seeds. He grows the seeds for two months and charts the growth every 2 days. What is wrong with his experiment?

a. More than one variable is being tested.

b. The student should have a larger number of pots.

c. There is no way of measuring the outcome.

d. There is no control set-up.

32. A scientific study showed that the depth at which algae were found in a lake varied from day to day. On clear days, the algae were found as much as 6 meters below the surface of the

water but were only 1 meter below the surface on cloudy days. Which hypothesis best explains these observations?

a. Nitrogen concentration affects the growth of algae.

b. Precipitation affects the growth of algae.

c. Light intensity affects the growth of algae.

d. Wind currents affect the growth of algae.

Unit 2- Atomic Theory and Structure

ATOMIC THEORY

HISTORY OF THE ATOM

The original idea (400 B.C.) came from ______________________, a Greek philosopher.

He expressed the belief that all matter is composed of very small, indivisible particles, which he

named atomos. John Dalton (1766-1844), an English school teacher and chemist, proposed his

atomic theory of matter in 1803. Dalton’s Atomic Theory states that:

1. All matter is made of tiny __________________________ particles called atoms.

2. Atoms of the ____________ element are identical; those of different atoms are different.

3. Atoms of different elements combine in whole number ________________ to form

compounds

4. Chemical reactions involve the rearrangement of atoms. No _______ atoms are created or

destroyed.

PARTS OF THE ATOM

Because of Dalton’s atomic theory, most scientists in the 1800s believed that the atom was like a

tiny solid ball that could not be broken up into parts. In 1897, a British physicist, J.J. Thomson,

discovered that this solid-ball model was not accurate. Thomson’s experiments used a

__________________ ray tube. It is a vacuum tube - all the air has been pumped out. Because

these rays originate at the ____________________, they are called cathode rays. Thomson

concluded that cathode rays are made up of invisible, _________________________ charged

particles referred to as electrons. From Thomson’s experiments, scientists had to conclude that

atoms were not just neutral _________________, but somehow were composed of electrically

charged particles. Matter is not negatively charged, so atoms can’t be negatively charged either.

If atoms contained extremely light, negatively charged particles, then they must also contain

positively charged particles — probably with a much greater _____________ than electrons. J.J.

Thomson said the atom was like ______________ pudding, a popular English dessert.

In 1909, a team of scientists led by Ernest Rutherford in England carried out the first of

several important experiments that revealed an arrangement far different from the plum pudding

model of the atom. The experimenters set up a lead-shielded box containing radioactive

polonium, which emitted a beam of positively charged subatomic particles through a small hole.

13


The sheet of ________________ foil was surrounded by a screen coated with zinc sulfide, which

glows when struck by the positively charged particles of the beam. The ________________

particles were expected to pass through without changing direction very much because

Rutherford thought the mass was evenly distributed in the atom. Because most of the particles

passed through the foil, they concluded that the atom is nearly all _______________

______________. Because so few particles were deflected, they proposed that the atom has a

small, dense, positively charged central core, called a ____________________. Alpha particles

are deflected by it if they get close enough to the nucleus.

R.A. Millikan found the charge of an electron to be -1.60 x 10-19 Coulombs in his

famous oil drop experiment. In 1910, J.J. Thomson discovered that neon consisted of atoms of

two different masses. Atoms of an element that are chemically alike but differ in mass are called

______________________ of the element. Because of the discovery of isotopes, scientists

hypothesized that atoms contained still a third type of particle that explained these differences in

mass. Calculations showed that such a particle should have a mass ____________________ to

that of a proton but no electrical _______________. The existence of this neutral particle, called

a neutron, was confirmed in the early 1930s. James _________________ is given credit for

discovering the neutron.

14


NAME SYMBOL CHARGE RELATIVE MASS

1/2000

proton

no

MODERN VIEW OF THE ATOM

The atom has two regions and is ___-dimensional. The nucleus is at the ___________________

and contains the protons and _____________________. The electron cloud is the region where

you might find an electron and most of the volume of an atom. The atomic _________________

of an element is the number of protons in the nucleus of an atom of that element. The number of

protons determines ____________________ of an element, as well as many of its chemical and

physical properties. Because atoms have no overall electrical charge, an atom must have as

many ____________________ as there are protons in its nucleus. Therefore, the atomic number

of an element also tells the number of electrons in a neutral atom of that element. The mass of a

neutron is almost the same as the mass of a ________________. The sum of the protons and

neutrons in the nucleus is the ________________ number of that particular atom.

_____________________ of an element have different mass numbers because they have

different numbers of _______________, but they all have the same atomic number.

AVERAGE ATOMIC MASS

The atomic mass is the weighted average mass of all the naturally occurring isotopes of that

element.

To determine the average atomic mass, first calculate the contribution of each isotope to the

average atomic mass, being sure to convert each ___ a fractional abundance. The average atomic

mass of the element is the sum of the mass contributions of each isotope.

Elements can be represented by using the symbol of the element, the mass number and the

atomic number. The mass number is the __________________ mass rounded to a whole

number.

15


1. Determine the following for the fluorine-19 atom.

a) number of protons b) number of neutrons c) number of electrons

d) atomic number e) mass number

2. Repeat #1 for bromine-80.

3. If an element has an atomic number of 34 and a mass number of 78, what is the

a) number of protons b) number of neutrons

c) number of electrons d) complete symbol

4. If an element has 91 protons and 140 neutrons, what is the

a) atomic number b) mass number

c) number of electrons d) complete symbol

5. If an element has 78 electrons and 117 neutrons what is the

a) atomic number b) mass number

c) number of protons d) complete symbol

Practice/HomeworkIsotopes and Subatomic Particles

Complete the chart

Isotope symbol Atomic # Mass Protons Neutrons Electrons8 9

77 54

12 1338 50

106 15711 12 117 14

126 85

16


Isotope symbol Atomic # Mass Protons Neutrons Electrons47 6140 5124 28

MOLESWe measure ________________ in grams. We measure volume in __________________. We

count pieces in _________________. The number of moles is defined as the number of

__________________ atoms in exactly ____ grams of carbon-12. ____ mole is 6.022 x 1023

particles. 6.022 x 1023 is called __________________ number. Representative particles are the

smallest pieces of a substance. For a molecular compound it is a(n) ______________________.

For an ionic compound it is a ______________________ ______________. For an element it is

a(n) ________________.

How many oxygen atoms are in the following?

a) CaCO3 b) Al2(SO4)3

How many total ions are in the following?

a) CaCl2 b) NaF c) Al2S3

MOLE CONVERSIONS

1. How many atoms of carbon are there in 1.23 moles of carbon?

2. How many molecules of CO2 are in 4.56 moles of CO2?

3. How many atoms of iron are in 0.600 moles of iron?

4. How many moles are in 7.78 x 1024 formula units of MgCl2?

5. How many moles of water are 5.87 x 1022 molecules of water?

6. How many moles of aluminum are 1.2 x 1024 atoms of aluminum?

17


Calculate the number of particles (atoms, ions or molecules) in each of the following.

a) 3.4 moles Na2S b) 0.0020 moles Zn

c) 1.77 x 10-11 moles C d) 92.35 moles O2

Calculate the number of moles in each of the following.

a) 3.4 x 1024 molecules HCl b) 8.7 x 1021 atoms Zn

c) 1.77 x 1018 ions Al+3 d) 2.66 x 1026 atoms Cu

MOLAR MASS

Molar mass is the generic term for the mass of one _____________. It may also be referred to as

gram molecular mass, gram formula mass, and gram atomic mass. The unit is ______________.

To determine the molar mass of an element, find the element’s symbol on the periodic table and

round the mass so there is __________ digit beyond the decimal.

18

moles

VolumeRepresentative particles

mass

Use6.02x1023

Use 22.4 L

Use molar mass

Remember DIMO:Divide InMultiplyOut


Determine the molar mass of the each of the following elements.

a) sulfur (S) b) chromium (Cr) c) bromine (Br)

To determine the molar mass of a compound, find the mass of all elements in the compound.

If necessary, ___________________ an element’s mass by the subscript appearing beside that

element in the compound’s formula (or ________________ of the subscripts).

Calculate the molar mass of each of the following compounds.

a) Na2S b) N2O4 c) C6H12O6 d) Ca(NO3)2

MASS-PARTICLE/MOLE CONVERSIONS

1. How many atoms of lithium are in 1.00 g of Li?

2. How many molecules of sodium oxide are in 42.0 g of Na2O?

3. How much would 3.45 x 1022 atoms of uranium (U) weigh?

4. How many moles of magnesium are in 56.3 g of Mg?

5. How many moles is 5.69 g of NaOH?

6. How many grams of sodium chloride are in 3.45 moles of NaCl?

7. How many moles is 4.8 g of CO2?

8. How many grams is 9.87 moles of H2O?

9. How many molecules are in 6.8 g of CH4?

10. What is the mass of 49.0 molecules of C6H12O6?

GASES

Many of the chemicals we deal with are gases. They are difficult to weigh, and we need to know

how many moles of gas we have. Two things affect the volume of a gas: temperature and

pressure. Standard temperature is ______ ºC, and standard pressure is ______ atm. Standard

temperature and pressure is abbreviated STP. At STP 1 mole of gas occupies ______ L. 22.4 L

is called the _____________ volume. Avogadro’s Hypothesis - At the same temperature and

pressure equal volumes of gas have the same number of _______________________.

19


GAS CONVERSIONS

1. What is the volume of 4.59 mole of CO2 gas at STP?

2. How many moles is 5.67 L of O2 at STP?

3. What is the volume of 8.8 g of CH4 gas at STP?

4. How many grams is 16.2 L of O2 at STP?

Calculate the number of liters in each of the following.

a) 3.10 x 1024 molecules Cl2 b) 8.7 moles Ne

c) 2.77 x 1018 atoms He d) 266 grams SO2

Homework/PracticePart 1--Convert between particles and moles

1. 24 atoms of sodium = _____ moles of sodium atoms

2. 5 molecules of chlorine gas = _____ moles of chlorine molecules

3. 900 atoms of silver = _____ moles of silver atoms

4. 2.89 x 1023 molecules of ammonia = _____ moles of ammonia molecules

5. 15 moles of arsenic atoms = ______ atoms of arsenic

6. 4.00 x 103 moles of barium atoms = __________ atoms of barium

Part 2--Convert between mass and moles

7. Calculate the mass of 1.000 mole of CaCl2

8. Calculate grams in 3.0000 moles of CO2

9. Calculate number of moles in 32.0 g of CH4

10. Calculate moles in 168.0 g of HgS

11. Calculate moles in 510.0 g of Al2S3

12. How many moles are in 27.00 g of H2O

13. What is the mass of 2.55 moles Cu2CrO4

20


Part 3- Multiple steps

14. Arrange the following in order of increasing weight.

a. 10.4 g of sulfur

b. 0.179 moles of iron

c. 6.33 x 1025 atoms of

hydrogen

d. 0.77 moles of N2

15. How many grams would 8.1 1021 molecules of sucrose (C12H22O11) weigh?

16. How many atoms are in a 2.0 kg ingot of gold? (Note mass units.)

17. What is the mass of 2.3x1024 molecules of KCl?

18. Calculate the number of molecules in 50.0 grams of H2SO4

19. Calculate the number of molecules in 100. grams of KClO4

20. Calculate the number of molecules in 8.76 grams of NaOH

21. Calculate the mass of 1.2x1022 molecules of Fe3(PO4)2

22. Calculate mass of 7.2x1024 molecules of Na2CO3

NUCLEAR CHEMISTRYNuclear chemistry is the study of the structure of _________________ nuclei and the changes

they undergo. Marie Curie named the process by which materials such as uranium give off rays

radioactivity; the rays and particles emitted by a radioactive source are called

__________________. As you may recall, isotopes are atoms of the same element that have

different numbers of _________________. Isotopes of atoms with unstable nuclei are called

______________________. These unstable nuclei emit radiation to attain more stable atomic

configurations in a process called radioactive ________________. During radioactive decay,

unstable atoms lose _________________ by emitting one of several types of radiation.

TYPES OF RADIATION

The three most common types of radiation are alpha (α), ____________ (β), and gamma (γ). An

alpha particle (α) has the same composition as a __________________ nucleus - two protons

and ________ neutrons - and is therefore given the symbol _________. The charge of an alpha

particle is 2+ due to the presence of the two ___________________. Because of their mass and

charge, alpha particles are relatively slow-moving compared with other types of radiation. Thus,

21

He


alpha particles are not very ________________________ - a single sheet of paper stops alpha

particles. A beta particle is a very-fast moving ______________________ that has been emitted

from a neutron of an unstable nucleus. Beta particles are represented by the symbol _________.

The zero superscript indicates the insignificant mass of an electron in comparison with the mass

of a ____________________. The –1 subscript denotes the _____________________ charge of

the particle. Beta radiation consists of a stream of fast-moving electrons. Because beta particles

are both lightweight and fast moving, they have _____________________ penetrating power

than alpha particles. A thin metal foil is required to stop beta particles. Gamma rays are high-

energy (_________________ wavelength) electromagnetic radiation. They are denoted by the

symbol __________. As you can see from the symbol, both the subscript and superscript are

zero. Thus, the emission of gamma rays does not change the __________________ number or

mass number of a nucleus. Gamma rays almost always accompany alpha and beta radiation, as

they account for most of the energy loss that occurs as a nucleus decays.

NAME SYMBOL FORMULA MASS CHARGE DESCRIPTION

Alpha 4

2

β -1

0 High energy

radiation

NUCLEAR STABILITY and DECAY

Radioactive nuclei undergo decay in order to gain _____________________. All elements with

atomic numbers greater than 83 are radioactive. Nuclear equations are used to show nuclear

transformations. Balanced nuclear equations require that both the ____________________

number and the mass number must be balanced.

When beryllium-9 is bombarded with alpha particles (helium nuclei), a neutron is produced.

The balanced nuclear reaction is given as:

________________________________________________

22


The atomic number (the number on the bottom) determines the identity of the element.

When nitrogen-14 is bombarded with a neutron, a proton is produced. The balanced nuclear

equation can be written as:

_________________________________________________________

Polonium-230 undergoes alpha decay:

________________________________________________

Uranium-234 undergoes alpha decay:

________________________________________________

Cobalt-50 undergoes beta decay:

____________________________________________________

Provide symbols for each of the following: neutron ___________, proton ___________ or

___________, and the positron ___________.

What element is formed when iron-60 undergoes beta decay? Give the atomic number and

mass number of the element. ____________

Write a balanced nuclear equation for the alpha decay of the following radioisotope,

uranium-235.

____________________________________________________________

Nitrogen-12 decays into a positron and another element. Write the balanced nuclear

equation.

____________________________________________________________

Uranium-238 is bombarded with a neutron. One product forms along with gamma radiation.

Write the balanced nuclear equation.

____________________________________________________________

Nitrogen-14 is bombarded with deuterium (hydrogen-2). One product forms along with an

alpha particle. Write the balanced nuclear equation.

____________________________________________________________

23


RADIOACTIVE DECAY RATES

Radioactive decay rates are measured in half-lives. A half-life is the time required for one-half

of a radioisotope’s nuclei to ________________ into its products. For example, the half-life of

the radioisotope strontium-90 is 29 years. If you had 10.0 g of strontium-90 today, 29 years from

now you would have 5.0 g left. The decay continues until negligible strontium-90 remains.

Iron-59 is used in medicine to diagnose blood circulation disorders. The half-life of iron-59

is 44.5 days. How much of a 2.000-mg sample will remain after 133.5 days?

Cobalt-60 has a half-life of 5.27 years. How much of a 10.0 g sample will remain after

21.08 years?

Carbon-14 has a half-life of 5730 years. How much of a 250. g sample will remain after

5730 years?

FISSION and FUSION

Heavy atoms (mass number > 60) tend to break into smaller atoms, thereby increasing their

________________________. Using a neutron to split a nucleus into fragments is called nuclear

_______________________. Nuclear fission releases a large amount of energy and several

neutrons. Since neutrons are products, one fission reaction can lead to more fission reactions, a

process called a ________________ reaction. A chain reaction can occur only if the starting

material has enough mass to sustain a chain reaction; this amount is called __________________

mass. The _____________________ of atomic nuclei is called nuclear fusion. For example,

nuclear fusion occurs within the Sun, where hydrogen atoms fuse to form __________________

atoms. Fusion reactions can release very large amounts of energy but require extremely high

temperatures. For this reason, they are also called _____________________________ reactions.

APPLICATIONS OF NUCLEAR REACTIONS

Geiger counters, scintillation counters, and film badges are devices used to detect and measure

radiation. Geiger counters use ________________________ radiation, which produces an

electric current in the counter, to rate the strength of the radiation on a scale. Film badges are

often used to monitor the approximate radiation ______________________ of people working

24


with radioactive materials. Scintillation counters measure ionizing radiation. With proper safety

procedures, radiation can be useful in industry, in scientific experiments, and in medical

procedures. Nuclear power plants use the process of nuclear fission to produce heat in nuclear

reactors. The heat is used to generate steam, which is then used to drive __________________

that produce electricity. A radiotracer is a radioisotope that emits non-ionizing radiation and is

used to signal the presence of an element or of a specific substance. Radiotracers are used to

detect ______________________ and to analyze complex chemical reactions. Ionizing radiation

has many uses. A(n) _______________ is ionizing radiation, and ionizing radiation can be used

in medicine to kill cancerous cells. Most medical devices require sterilization after they are

packaged, and another trend has been the move to sterilization by __________________

radiation as opposed to other methods such as ethylene oxide gas. Advantages of gamma

irradiation include ______________, cost-effectiveness, and the elimination of the need for

special packaging. Chemical reaction rates are greatly affected by changes in temperature,

_____________________, and concentration, and by the presence of a catalyst. In contrast,

nuclear reaction rates remain ____________________ regardless of such changes. In fact, the

half-life of any particular radioisotope is constant. Because of this, radioisotopes, especially

carbon-14, can be used to determine the ____________ of an object. The process of determining

the age of an object by measuring the amount of a certain radioisotope remaining in that object is

called radiochemical dating.

EFFECTS OF NUCLEAR REACTIONS

Any exposure to radiation can damage living ____________. Gamma rays are very dangerous

because they penetrate ______________________ and produce unstable and reactive molecules,

which can then disrupt the normal functioning of cells. The amount of radiation the body

absorbs (a dose) is measured in units called rads and ____________. Everyone is exposed to

radiation, on average 100–300 millirems per year. A dose exceeding ____________ rem can be

fatal.

25


Atomic Theory, The Mole, and Nuclear Chemistry- Practice Test

1. Given the work of Dalton, please check the box for the postulate(s) that have since been proven to be incorrect. Explain what we now know to be the true case.

[] All atoms of a specific element are identical.[] Compounds consist of atoms of different elements combined together.[] Atoms of different elements have different masses.

Directions: For the scientist listed below, explain what was done in the experiment, what knowledge was developed as a result, 2. Rutherford

3. Thomson

Directions: Fill in the table for the following isotopes.

Isotope Atomic # Mass # Protons Neutrons Electrons4. H-15. Cu-656. 18 407. 19 9

8. What is the charge of a beta particle?

Directions: Solve the following problems be sure to include the correct unit with your final answer.

9. Given the equation: X + The nucleus represented by X is

10. How many moles of sodium are 6.02 x 10 23 atoms of sodium?

11. What is the mass of 6 moles of Carbon?

12. How many atoms are in 45g of Neon?


13. What is the approximate formula mass of Ca(NO3)2

a. 70b. 82

c. 102d. 150

e. 164

14. How many molecules are in 1 mole of water?a. 3b. 54

c. 6.02x1023

d. 2(6.02x1023)e. 3(6.02x102

3)

26


How many atoms are represented in the formula Ca3(PO4)2

a. 5b. 8

c. 9d. 12

e. 13

15. Four grams of hydrogen gas at STP containa. 6.02x1023 atomsb. 12.04x1023atomsc. 12.04x1046atoms

d. 1.2x1022moleculese. 12.04x1023molecules

16. What is the mass in grams of 1 mole of KAl(SO4)2*12H2Oa. 132b. 180

c. 394d. 474

e. 516

17. Compared to the charge and mass of a proton, an electron hasa. the same charge and a smaller mass b. the same charge and the same mass c. an opposite charge and a smaller mass d. an opposite charge and the same mass

18. When alpha particles are used to bombard gold foil, most of the alpha particles pass through undeflected. This result indicates that most of the volume of a gold atom consists of ____.

a. deuterons b. neutrons

c. protons d. unoccupied space

19. A proton has approximately the same mass asa. a neutron b. an alpha particle

c. a beta particle d. an electron

20. A neutron has approximately the same mass as aa. an alpha particle b. a beta particle

c. an electron d. a proton

21. Which symbols represent atoms that are isotopes?a. C-14 and N-14 b. O-16 and O-18

c. I-131 and I-131 d. Rn-222 and Ra-222

22. Which atom contains exactly 15 protons?a. P-32 b. S-32

c. O-15 d. N-15

23. An ion with 5 protons, 6 neutrons, and a charge of 3+ has an atomic number of

27


a. 5 b. 6 c. 8 d. 11

24. What is the mass number of an atom which contains 28 protons, 28 electrons, and 34 neutrons?

a. 56 b. 62 c. 90 d. 28

25. What is the total number of atoms represented in the formula CuSO4 . 5H2O?a. 8 b. 13 c. 21 d. 27

26. What is the gram formula mass of K2CO3?a. 138 g b. 106 g

c. 99 g d. 67 g

27. What is the total number of atoms contained in 2.00 moles of nickel?a. 58.9 b. 118

c. 6.02 x 1023 d. 1.2 x 1024

28. What is the total number of moles of hydrogen gas contained in 9.03 x 1023moleculesa. 1.5 moles b. 2.00 moles

c. 6.02 moles d. 9.03 moles

29. What is the mass in grams of 3.0 x 1023 molecules of CO2?a. 22 g b. 44 g

c. 66 g d. 88 g

30. The amount of substance having 6.022 x 1023 of any kind of chemical unit is called a(n):a. formula b. mass number

c. mole d. atomic weight

31. The total number of atoms in the formula of aluminum dichromate, Al2(Cr2O7)3 is:a. 5 b. 29 c. 17 d. 11

32. The total number of OXYGEN atoms in the formula of aluminum dichromate, Al2(Cr2O7)3 is:

a. 21 b. 10 c. 29 d. 7

33. The formula mass of calcium hydroxide, Ca(OH)2 is:

28


a. 57.05 grams b. 74.10 grams

c. 128 gramsd. 97.07 grams

29


34. The formula mass of ammonium chlorate, NH4ClO3 is:a. 101.5 g b. 78.06 g

c. 211.43 gd. 172.40 g

35. What is the molar mass of the gas butane, C4H10?a. 13.02 grams b. 485.2 grams

c. 68 24 gramsd. 58.14 grams

36. The molar mass of sodium chloride, NaCl is:a. 69.71 grams b. 2 grams

c. 6.022 x 1023 gramsd. 58.44 grams

37. The formula mass of magnesium hydroxide, Mg(OH)2 is:a. 42.33 grams b. 58.33 grams

c. 41.32 grams d. 5 grams

38. What is the mass in grams of 3 moles of water molecules, H2O?a. 54.06 grams b. 21.02 grams

c. 0.166 grams d. 6.01 grams

39. What is the mass of 4 moles of hydrogen molecules (H2)?a. 4.04 grams b. 8.08 grams

c. 3.96 gramsd. 1.98 grams

40. What is the mass in grams of 10 moles of ammonia, NH3?a. 170.4 grams b. 0.587 grams


41. How many moles of water molecules, H2O, are present in a 42 gram sample of water?a. 23.98 molesb. 0.429 moles

c. 2.33 moles d. 757 moles

30


42. How many moles of methane molecules, CH4, are in 80 grams of methane?a. 0.201 moles b. 4.98 moles

c. 6.022 x 1080 molesd. 1284 moles

31


43. How many moles of calcium hydroxide, Ca(OH)2 are in 150 grams of the compound?a. 2.02 moles b. 224.1 moles

c. 0.494 moles d. 11115 moles

44. About how many atoms of helium would be found in 2 grams of helium?a. 4.00260b. 6.02 x 1023

c. 2 d. 3.01 x 1023

45. By knowing the number of electrons in a neutral atom, you should also be able to determine

a. the number of neutrons in the neutral atom b. the number of protons in the neutral atom c. the atomic number of the neutral atom d. the mass of the neutral atom e. two of these

46. How many oxygen atoms are there in one formula unit of Al2(SO4)3?a. 3 b. 4 c. 7 d. 12

47. The average mass of a magnesium atom is 24.31. If you were able to select and measure a single atom of magnesium, the chance that you would select an atom of mass 24.31 is about:

a. 0% b. 0.31% c. 24.31%

d. greater than 50% e. 100%

48. Which of the following arrangements represent different isotopes of the same element?

i. 12 protons, 11 neutrons, 12 electrons ii. 11 protons, 12 neutrons, 11 electrons

iii. 10 protons, 12 neutrons, 12 electrons iv. 11 protons, 12 neutrons, 10 electrons v. 12 protons, 12 neutrons, 12 electrons

a. 1 and 5 b. 2 and 4

c. 2, 3, 4 and 5 d. all of these qualify

32


e. None of these qualify

49. If the abundance of 6Li (6.015121 amu) is 7.500% and the abundance of 7Li (7.016003 amu) is 92.500%, what is the average atomic mass?

a. 6.0750 amu b. 6.0902 amu

c. 6.9250 amu d. 6.9409 amu

50. Which of following is not true of the carbon-14 atom?a. It has six protons b. It has an average mass of 12.011 amu. c. It has six electrons d. It has eight neutrons e. It is the less common than carbon-12

51. A particle with 15 protons and 18 electrons would be symbolized as:a. Ar b. Ar3-

c. P3- d. P3+

e. Ar3+

52. Which of these is the correct number of particles in this nuclide? a. 34 protons, 79 neutrons, 2 electrons b. 34 protons, 45 neutrons, 32 electrons c. 34 protons, 45 neutrons, 2 electrons d. 34 protons, 45 neutrons, 36 electrons e. 34 protons, 113 neutrons, 36 electrons

53. Which of the following have equal numbers of neutrons?

a. I, II and III b. II and III c. I and V

d. I and IV e. II, III and IV

33


54. The element hafnium (Hf) has five stable isotopes. The correct number of nuclear particles in an atom of hafnium-178 is:

a. 72 protons, 178 neutrons b. 72 protons, 72 electrons c. 106 protons, 72 neutrons

d. 72 protons, 106 neutrons e. 72 protons, 106 neutrons,

72 electrons

55. J.J. Thomson's model of the atom can be summarized with the visual image of:a. planets orbiting the sun b. plum pudding c. bees around a hive

d. a small central nucleus and an electron cloud

e. none of the above

56. The number of errors contained in the table below is:

Nuclide protons neutrons electrons massSodium-23 11 12 11 23Cobalt-59 27 22 27 59

Tungsten-184 74 110 184 184Fluorine-19 10 9 10 19a. one b. two

c. three d. four

e. five

57. + _____ + 2 In the equation shown here, the missing particle is:a.b.

c.d.

e.

58. Identify the missing particle in the following nuclear reaction: → _____ + a.

b. c. d.

59. For the most common types of radioactive decay, the order of least penetrating to human tissue, to most penetrating to human tissue is:

a. gamma, beta, alphab. alpha, beta, gamma

c. beta, gamma, alpha d. gamma, alpha, beta

34


60. Very large nuclei tend to be unstable because of the:a. repulsive forces between protons b. attraction of protons for neutronsc. repulsive forces between neutrons d. attraction of electrons for the positively charged nucleus e. repulsive forces between electrons

61. An alpha () particle is essentially a ____________________ nucleus.a. plutoniumb. helium

c. hydrogen d. uranium

e. carbon-12

62. Phosphorus-15 has a half-life of 14 days. What proportion of the original phosphorus-15 remains after 8 weeks?

a. 1/2 b. 1/16

c. 1/4 d. 1/32

e. 1/8

63. The nuclide radium-226 is the daughter nuclide resulting from the decay of what parent nuclide?

a. radon-222 b. polonium-214 c. thorium-230

d. thorium-228 e. radium-225

64. An electron emitted from the nucleus during some kinds of radioactive decay is known as:

a. A gamma rayb. A positron

c. A beta () particled. An alpha () particle

65. A process in which a very heavy nucleus splits into more-stable nuclei of intermediate mass is called:

a. nuclear fission b. radiocarbon datingc. a chain reaction

d. nuclear fusion e. radioactive decay

35

Unit 3- Electrons and Periodicity

ELECTRONS IN ATOMS

LIGHT

Light is a kind of electromagnetic _____________________. All forms of electromagnetic

radiation move at 3.00 x 108 m/s. The ______________ is the baseline of a wave. The crest is

the high point on a wave, and the trough is low point on a wave. The amplitude of a wave is the

wave’s _____________ from the origin to a crest, or from the origin to a trough. Wavelength

(represented by λ, the Greek letter lambda) is the ___________________ distance between

equivalent points on a continuous wave. Wavelength is the distance from crest to crest or trough

to trough and is usually expressed in meters (m). _____________________ (represented by f ) is

the number of “waves” that pass a given point per second, and the units are cycles/sec or hertz

(Hz)

c = f λ c = the speed of light

Frequency and wavelength are __________________ related, which means that as one goes up

the other goes _____________. Different frequencies of light correspond to different colors of

light. In 1900, the German physicist Max Planck began searching for an explanation as he

studied the light emitted from ___________________ objects. Matter can gain or lose energy

only in small, specific amounts called _______________. That is, a quantum is the minimum

amount of energy that can be gained or lost by a(n) ____________. That is, while a beam of

light has many wavelike characteristics, it also can be thought of as a stream of tiny particles, or

bundles of energy, called ________________. Thus, a photon is a particle of electromagnetic

radiation with no _____________ that carries a quantum of energy. Planck went further and

demonstrated mathematically that the energy of a quantum is ___________________ related to

the frequency of the emitted radiation.

E = h f

E = energy of the photon (J – Joules); f = frequency (Hz); h = Planck’s constant (J.s)

The energy of radiation increases as the radiation’s frequency, f, __________________.

Scientists knew that the wave model of light could not explain a phenomenon called the

____________________ effect. In the photoelectric effect, electrons, called

__________________________, are emitted from a metal’s surface when light of a certain

_______________________ shines on the surface. Einstein proposed that for the photoelectric


effect to occur, a photon must possess, at a minimum, the energy required to _______________

an electron from an atom of the metal.

THE BOHR MODEL OF THE ATOM

Niels Bohr, a young Danish physicist working in Rutherford’s laboratory in 1913, suggested that

the single electron in a ___________________ atom moves around the nucleus in only certain

allowed circular orbits. The atom looked like a miniature _________________ system. The

nucleus is represented by the sun, and the electrons act like the planets. The orbits are circular

and are at different levels. Amounts of ___________________ separate one level from another.

(Modern View: The atom has two regions and is 3-dimensional. The nucleus is at the

_________________ and contains the protons and neutrons. The electron _________________

is the region where you might find an electron and most of the volume of an atom.) Bohr

proposed that electrons must have enough energy to keep them in constant motion around the

___________________. Electrons have energy of motion that enables them to overcome the

attraction of the _________________ nucleus. Further away from the nucleus means more

energy. Electrons reside in ________________ levels.

THE QUANTUM MECHANICAL MODEL

Building on Planck’s and Einstein’s concepts of ____________________ energy (quantized

means that only certain values are allowed), Bohr proposed that the hydrogen atom has only

certain allowable energy ______________. The lowest allowable energy state of an atom is

called its _______________ state. When an atom gains energy, it is said to be in a(n)

__________________ state. When the atom is in an excited state, the electron can drop from the

higher-energy orbit to a _______________-energy orbit. As a result of this transition, the atom

emits a ____________________ corresponding to the difference between the energy levels

associated with the two orbits.

ATOMIC AND EMISSION SPECTRA

By heating a gas of a given element with electricity, we can get it to give off _______________.

Each element gives off its own characteristic colors. The spectrum can be used to

__________________ the atom. These are called line _______________. Each is unique to an


element. The spectrum of light released from excited atoms of an element is called the

_________________ spectrum of that element. As the electrons fall from the excited state, they

__________________ energy in the form of light. The further they fall, the ________________

the energy. This results in a higher frequency.

Use the Chemistry Reference Tables to answer the following:

(a) An electron falls from energy level 5 to 3. What is the wavelength of the light emitted?

(b) An electron falls from energy level 6 to 2. What is the wavelength of the light emitted?

(c) An electron falls from energy level 3 to 1. What type of electromagnetic radiation is

emitted (infrared, visible or ultraviolet)?

(d) An electron falls from energy level 4 to 2. What type of electromagnetic radiation is

emitted (infrared, visible or ultraviolet)?

(e) An electron falls from energy level 5 to 2. What color of visible light is emitted?

(f) An electron falls from energy level 3 to 2. What color of visible light is emitted?

MORE QUANTUM MECHANICAL MODEL

Like Bohr’s model, the quantum mechanical model limits an electron’s energy to certain values.

The space around the nucleus of an atom where the atom’s electrons are found is called the

electron ________________. A three-dimensional region around the nucleus called an atomic

__________________ describes the electron’s probable location. In general, electrons reside in

principal ________________ levels. As the energy level number increases, the orbital becomes

_______________, the electron spends more time ___________________ from the nucleus, and

the atom’s energy level increases. Principal energy levels contain energy

___________________. Principal energy level 1 consists of a single sublevel, principal energy

level 2 consists of __________ sublevels, principal energy level 3 consists of three sublevels,

and so on. Sublevels are labeled s, p, d, or f. The s sublevel can hold 2 electrons, the p sublevel

can hold _____ electrons, the d sublevel can hold 10 electrons, and the f sublevel can hold 14

electrons. Sublevels contain __________________. Each orbital may contain at most ________

electrons. There is one s orbital for every energy level, and the s orbital is

____________________ shaped. They are called the 1s, 2s, 3s, etc… orbitals. The p orbitals


start at the second energy level, reside along ______ different directions and have 3 different

________________ shapes. The d orbitals start at the ________________ energy level and have

____ different shapes. The f orbitals start at the fourth energy level and have ______ different

shapes.

ELECTRON CONFIGURATIONS

Electron configurations represent the way electrons are arranged in atoms. The Aufbau principle

states that electrons enter the __________________ energy first. This causes difficulties

because of the ________________ of orbitals of different energies. At most there can be only 2

electrons per orbital, and they must have __________________ “spins.” Hund’s rule states that

when electrons occupy orbitals of equal energy, they don’t _________ up with an electron of

opposite spin until they have to.

Let’s determine the electron configuration for phosphorus. ______________________________

Let’s determine the electron configuration for chromium. _______________________________

Write the electron configuration for aluminum (Al). ________________________________

Write the electron configuration for neon (Ne). ____________________________________

Write the electron configuration for calcium (Ca). __________________________________

Write the electron configuration for iron (Fe). _____________________________________

Write the electron configuration for bromine (Br). _________________________________

To identify an element with a given electron configuration, add the _________________

numbers together and find the element with that atomic number.

Directions: Identify the element with the following electron configuration:

a. 1s2 2s2 2p6 3s2 3p4 _________________________________

b. 1s2 2s2 2p6 3s2 3p6 4s2 3d9 _________________________________

c. 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p2 _________________________________

Electron Configuration Using a Noble Gas Abbreviation - In order to write this type of

configuration, find the _______________ gas (from Group 8A) that comes before the element in

question. Put the symbol for the noble gas in _____________________ and then write the part

of the configuration that follows to reach the desired element.


Write the electron configuration using a noble gas abbreviation for:

magnesium (Mg) _________________________ • nickel (Ni) ___________________

fluorine (F) _________________________ • silicon (Si) ___________________

zirconium (Zr) _________________________

VALENCE ELECTRONS

The electrons in the ______________________ energy level are called valence electrons. You

can also use the periodic table as a tool to predict the number of valence electrons in any atom in

Groups 1, 2, 13, 14, 15, 16, 17, and 18. All atoms in Group 1, like hydrogen, have __________

valence electron. All atoms in Group 2 have two, in Group 13 have _______, in Group 14 have

four, in Group 15 have five, in Group 16 have six, and in Group 17 have ________ valence

electrons. All atoms in Group 18 have eight valence electrons, except helium which only has

two. All atoms in sublevels d and f have _________ valence electrons.

How many valence electrons does each of the following elements have?

a) carbon (C)

b) bromine (Br)

c) iron (Fe)

d) potassium (K)

e) aluminum (Al)

LEWIS DOT DIAGRAMS

Because valence electrons are so important to the behavior of an atom, it is useful to represent

them with symbols. A Lewis dot diagram illustrates ___________________ electrons as dots (or

other small symbols) around the chemical symbol of an element. Each dot represents

_____________ valence electron. In the dot diagram, the element’s symbol represents the core

of the atom - the nucleus plus all the _______________ electrons.

Write a Lewis dot diagram for a) chlorine b) calcium c) potassium


PERIODIC TABLE

HISTORY

The Russian chemist, Dmitri ______________________ was studying the properties of the

elements and realized that the chemical and physical properties of the elements repeated in an

orderly way when he organized the elements according to increasing atomic ___________.

Mendeleev later developed an improved version of his table with the elements arranged in

horizontal ___________. This arrangement was the forerunner of today’s periodic table.

Patterns of changing properties repeated for the elements across the horizontal rows. Elements

in vertical ___________________ showed similar properties. Mendeleev grouped elements in

columns by similar properties in order of increasing atomic mass. He found some

inconsistencies and felt that the properties were more important than the mass, so he switched

order. Mendeleev left some _____________ in his periodic table, deciding there must be

undiscovered elements. He predicted their properties before they were found. Mendeleev is

considered to be the _________________ of the Periodic table. This repeated pattern (when

Mendeleev grouped elements in columns by similar properties) is an example of

__________________ in the properties of elements. Periodicity is the tendency to recur at

regular intervals. By 1860, scientists had already discovered _________ elements and

determined their atomic masses.

THE MODERN PERIODIC TABLE

Fifty years after Mendeleev, the British scientist Henry ________________ discovered that the

number of protons in the nucleus of a particular type of atom was always the same. When atoms

were arranged according to increasing atomic ___________________, the few problems with

Mendeleev's periodic table disappeared. Because of Moseley's work, the modern periodic table

is based on the atomic numbers of the elements. The statement that the physical and chemical

properties of the elements repeat in a regular pattern when they are arranged in order of

increasing atomic number is known as the periodic _____________. On the periodic table a

_________________, sometimes also called a series, consists of the elements in a horizontal

row. A __________________, sometimes also called a family, consists of the elements in a

vertical column. Elements are placed in columns by similar properties.


The elements in the A groups are called the __________________ elements. The B groups are

called the ____________________ elements. The two rows at the bottom of the table are called

the inner transition elements. Group 1A elements are the _________________ metals. Group

1A elements have ______ valence electron and form _______ ions after losing the one valence

electron. Group 2A elements are the alkaline earth metals. Group 2A elements have ______

valence electrons and form 2+ ions after losing the two __________________ electrons. Group

3A is called the _________________ group. Group 3A elements have ________ valence

electrons and form 3+ ions after losing the three valence electrons. Group _______ is called the

carbon group. Group 4A elements have four valence electrons and form 4+ ions after

___________________ the four valence electrons or 4- ions after ___________________ four

additional electrons. Group 5A is called the _____________________ group. Group 5A

elements have five valence electrons and form ________ ions after gaining three more electrons.

Group 6A is called the oxygen group. Group 6A elements have _______ valence electrons and

form 2- ions after ____________________ two more electrons. Group 7A is called the

____________________. Group 7A elements have seven valence electrons and form 1- ions

after gaining one more electron. The word halogen is from the Greek words for

“______________ former” so named because the compounds that halogens form with metals are

salt-like. Group 8A elements are the ________________ gases. Group 8A elements have eight

valence electrons except for helium which only has ________. The noble gases, with a full

complement of valence electrons, are generally unreactive. All transition elements have

_______ valence electrons.

How many valence electrons are in an atom of each of the following elements?

a) Magnesium (Mg) ______ b) Selenium (Se) ______ c) Tin (Sn) _____

METALS, NONMETALS AND METALLOIDS

Metals are elements that have ________________, conduct ____________ and electricity, and

usually bend without breaking. Most metals have one, two, or three valence electrons. All

metals except _________________ are solids at room temperature; in fact, most have extremely


_____________ melting points. A metal’s ___________________ is its ability to react with

another substance.

Consult the “Activity Series of Metals” in the Chemistry Reference Tables to determine the

more active metal.

a) cobalt (Co) or manganese (Mn) ________ b) barium (Ba) or sodium (Na) ________

Although the majority of the elements in the periodic table are _________________, many

nonmetals are abundant in nature. Most nonmetals don’t conduct electricity, are much poorer

conductors of heat than metals, and are __________________ when solid. Many are

______________ at room temperature; those that are solids lack the luster of metals. Their

_____________________ points tend to be lower than those of metals. With the exception of

carbon, nonmetals have five, six, seven, or eight valence electrons. A nonmetal’s reactivity is its

ability to react with another substance.

Consult the “Activity Series of Metals” in the Chemistry Reference Tables to determine the

less active nonmetal.

a) fluorine (F2) or chlorine (Cl2) _________ b) chlorine (Cl2) or iodine (I2) _________

__________________ have some chemical and physical properties of metals and other

properties of nonmetals. In the periodic table, the metalloids lie along the border between metals

and nonmetals. Some metalloids such as silicon, germanium (Ge), and arsenic (As) are

_____________________. A semiconductor is an element that does not conduct electricity as

well as a ________________, but does conduct slightly better than a nonmetal.

Match each element in Column A with the best matching description in Column B. Each

Column A element may match more than one description from Column B.

Column A Column B

1. strontium a. halogen

2. chromium b. alkaline earth metal

3. iodine c. representative element

d. transition element

PERIODIC TRENDS


Because the periodic table relates group and period numbers to valence electrons, it’s useful in

predicting atomic structure and, therefore, ______________________ properties.

Atomic Radius

Atomic radius is half the distance between two __________________ of a diatomic molecule.

Atomic size is influenced by two factors: (1) energy level – A _________________ energy level

is further away. (2) charge on nucleus - More charge (_________________) pulls electrons in

closer. As you go down a ___________________, each atom has another energy level so the

atoms get bigger. As you go across a period, the radius gets ____________________. Atoms

are in the same energy level, but as you move across the chart, atoms have a greater

___________________ charge (more protons). Therefore, the outermost electrons are closer.

Choose the element from the pair with the larger atomic radius.

a) lithium (Li) or beryllium (Be) _________ b) silicon (Si) or tin (Sn) _________

Choose the element from the pair with the smaller atomic radius.

a) silver (Ag) or gold (Au) _________ b) cesium (Cs) or barium (Ba) _______

Ionic Radius

When an atom gains or loses one or more electrons, it becomes a(n) ______________. Because

an electron has a negative charge, gaining electrons produces a _______________________

charged ion, an anion, whereas losing electrons produces a positively charged ion, a

________________. As you might expect, the loss of electrons produces a positive ion with a

radius that is ___________________ than that of the parent atom. Conversely, when an atom

gains electrons, the resulting negative ion is larger than the parent atom. Practically all of the

elements to the _____________ of group 4A of the periodic table commonly form positive ions.

As with neutral atoms, ___________________ ions become smaller moving across a period and

become larger moving down through a group. As you go down a group, you are adding a(n)

_________________ level. Ions get bigger as you go down.

Most elements to the right of group 4A (with the exception of the noble gases in group 8A) form

negative ions. These ions, although considerably larger than the positive ions to the left, also

decrease in ______________ moving across a period. Like the positive ions, the negative ions


increase in size moving down through a group. Across the period, nuclear charge

__________________ so they get smaller. Energy level changes between anions and cations.

Choose the element from the pair with the smaller radius.

a) silver (Ag) or the silver ion (Ag1+) _________

b) oxygen (O) or the oxygen ion (O2-) _________

For each of the following pairs, predict which atom is larger.

a) Mg, Sr _________ b) Sr, Sn _________ c) Ge, Sn _________

d) Ge, Br _________ e) Cr, W _________

For each of the following pairs, predict which atom or ion is larger.

a) Mg, Mg2+ _________ b) S, S2– _________ c) Ca2+, Ba2+ ______

d) Cl–, I– _________ e) Na+, Al3+ _________

Ionization Energy

Ionization energy (IE) is the amount of energy required to completely _____________________

an electron from a gaseous atom. Removing one electron makes a ________ ion. The energy

required to do this is called the first ionization energy. The _____________________ the

nuclear charge (# of protons), the greater IE. The distance from the ____________________

increases IE. As you go down a group, first IE decreases because the electron is further away,

thus there is more shielding by the _______________ electrons from the pull of the positive

nucleus. All the atoms in the same period have the same energy level. They have the same

shielding, but as you move across the chart there is a(n) _____________________ nuclear

charge. Therefore, IE generally increases from left to right.

Choose the element from the pair with the greater ionization energy.

a) silver (Ag) or iodine (I) _________ b) oxygen (O) or selenium (Se) ________

Choose the element from the pair with the smaller ionization energy.

a) chromium (Cr) or tungsten (W) ______ b) sodium (Na) or magnesium (Mg) _______

Electronegativity


Electronegativity is the tendency for an atom to ___________________ electrons to itself when

it is chemically combined with another element. Large electronegativity means it

_______________ the electron toward it. The further you go down a group, the farther the

electron is away from the nucleus and the _____________ electrons an atom has. It is harder to

attract extra electrons if the available energy level is far from the nucleus, so the

electronegativity _____________________. As you go across a row, electronegativity increases

as the ________________________ character of the elements decreases.

Choose the element from the pair with the greater electronegativity.

a) sodium (Na) or rubidium (Rb) _______ b) selenium (Se) or bromine (Br) _______

Choose the element from the pair with the smaller electronegativity.

a) magnesium (Mg) or calcium (Ca) _______ b) nitrogen (N) or oxygen (O) _______

Homework / PracticeWrite the configuration notation for each of the following elements:

1) sodium

2) iron

3) bromine

4) barium

Write the noble gas notation for each of the following elements:

5) cobalt

6) silver7) tellurium

8) radium

Determine what elements are denoted by the following electron configurations:

9) 1s22s22p63s23p4

10) 1s22s22p63s23p64s23d104p65s1

11) [Kr] 5s24d105p3

12) [Rn] 7s25f11

Write the orbital notation for the following:

13) carbon14) neon

15) sulfur16) P

17) B18) Na

Write configuration notation for atoms containing the following number of electrons:


19) 320) 6

21) 822) 13

Draw the Lewis Dot Notation for the following elements

23) Sodium

24) Sulfur

25) Silver

26) Aluminum

27) Antimony

28) Argon

Reference Labeling- Label the following on the blank periodic table on the next page--

29) Metals30) Nonmetals31) Metalloids32) Transition metals33) Actinides34) Lanthanides35) Alkali metals36) Alkaline earth metals37) Halogens38) Noble gases (inert gases)39) Group numbers: 1A, 2A, 3A, 4A, 5A, 6A, 7A, 8A40) Label the most likely charge of an ion from groups 1A, 2A, 5A, 6A, 7A, and Noble gases41) Show which way are periods (left to right or up and down)42) Show which way are groups/families (left to right or up and down)43) Using color, identify the s, p, d and f blocks on the table44) Label the rows with energy level numbers45) Using arrows, indicate the trends of increasing atomic radius, ionization energy, and

electronegativity (from left to right and top to bottom)46) Put a star in the box for each diatomic element47) Show the charge of the ions that form for silver (+1), zinc (+2), and aluminum (+3)


Electrons and Periodicity Practice Test

Directions: Match each of the following terms with a number or chemical symbol from the periodic table below.

1. Alkaline earth metals:

2. Halogens:

3. Noble gases

4. The transition metals

5. Draw the orbital notation for Sodium

6. Given the electron configuration, identify the element 1s2 2s2 2p6 3s2 2p6 3s2 3p6 4s2 3d7

7. Write the complete configuration notation for Silver

8. Write the shorthand method (Noble Gas notation) for Antimony:

9. Give the energy level for the valence electrons in Helium

10. Determine the color of light emitted when an electron jumps from the following quantum

levels n=4 to n=2

11. How many valence electrons does Carbon have?

12. Draw the Lewis Dot notation for Sodium

13. Describe why the atomic radius of elements increases as you go down a group.



14. The two main parts of an atom are the a. Principle energy levels and energy sublevelsb. Nucleus and kernelc. Nucleus and energy levelsd. Planetary electrons and energy levels

15. The sublevel that has only one orbital is identified by the lettera. s b. p c. d d. f

16. The sublevel that can be occupied by a maximum of ten electrons is identified by the letter

a. s b. p c. d d. f

17. An orbital may never be occupied bya. 1 electronb. 2 electrons

c. 3 electronsd. 0 electrons

18. An atom of beryllium consists of 4 protons, 5 neutrons, 4 electrons. The mass number of this atom is

a. 13 b. 9 c. 8 d. 5

19. Which of the following is the correct electron configuration for the bromide ion, Br-?a. [Ar] 4s24p5

b. [Ar] 4s23d104p5

c. [Ar] 4s23d104p6

d. [Ar] 4s23d104p65s1

e. [Ar] 4s23d103p6

20. Which is the first element to have 4d electrons in its electron configuration?

a. Ca

b. Sc

c. Rb

d. Y

e. La

21. When electrons in an atom in an excited state fall to lower energy levels, energy isa. absorbed, only b. released, only

c. neither released nor absorbed d. both released and absorbed

22. Which of the following elements has the greatest electronegativity?a. Mg b. K c. S d. F


23. Which of the following elements would react with chlorine in a one to one ratioa. Mg b. K c. S d. F


24. Which of the following elements would have the smallest radiusa. Mg b. K c. S d. F

25. Which of following elements has the lowest first ionization energya. Mg b. K c. S d. F

26. Which of the following elements is an alkali metal?a. Mg b. K c. S d. F

27. Which element's ionic radius is smaller than its atomic radius?a. neon b. nitrogen

c. sodium d. sulfur

28. Which three groups of the Periodic Table contain the most elements classified as metalloids (semimetals)?

a. 1, 2, and 13 b. 2, 13, and 14

c. 14, 15, and 16 d. 16, 17, and 18

29. Which element has the highest first ionization energy?a. sodium b. aluminum

c. calcium d. phosphorus

30. Which of the following elements has the smallest atomic radius?a. nickel b. cobalt

c. calcium d. potassium

31. Which set of elements contains a metalloid?a. K, Mn, As, Ar b. Li, Mg, Ca, Kr

c. Ba, Ag, Sn, Xe d. Fr, F, O, Rn

32. Atoms of elements in a group on the Periodic Table have similar chemical properties. This similarity is most closely related to the atoms'

a. number of principal energy levels b. number of valence electrons c. atomic numbers d. atomic masses

33. As atoms of elements in Group 16 are considered in order from top to bottom, the electronegativity of each successive element


a. decreases b. increases

c. remains the same

34. An atom of which of the following elements has the greatest ability to attract electrons?a. silicon b. sulfur

c. nitrogen d. chlorine

35. At STP, which substance is the best conductor of electricity?a. nitrogen b. neon

c. sulfur d. silver

36. A strontium atom differs from a strontium ion in that the atom has a greatera. number of electrons b. number of protons

c. atomic number d. mass number

37. Which gas is monatomic at STP?a. chlorine b. fluorine

c. neon d. nitrogen

38. How many valence electrons does an oxygen atom have? a. 2 b. 6 c. 8 d. 16

39. The identity of an element is determined by...a. the number of its protons. b. the number of its neutrons.

c. the number of its electronsd. its atomic mass.

40. Which of the following electron configurations represents the electron configuration for a magnesium cation (Mg2+)?

a. 1s22s22p63s2 b. 1s22s22p63s23p2

c. 1s22s22p6 d. 1s22s22p4

41. Which of the following atoms has the largest diameter? a. F b. Cl c. Br d. I

42. Which of the following elements has the greatest electronegativity? a. Si b. P c. N d. O

43. Which scientist noted a definite pattern in valence numbers and arranged an early periodic table in order of the elements atomic mass?

a. Enrico Fermib. Dmitri Mendeleev

c. Albert Einsteind. Madame Curie


44. The periodic law states that the properties of elements are periodic functions of theira. Massb. Symbol

c. atomic numberd. valence

45. Which of the following is a noble gas?a. Sodiumb. Gold

c. Chlorined. Neon

46. A gas is called "noble" becausea. it is normally unreactiveb. it is normally inertc. it has a complete outer energy level of electronsd. all of the above

47. Of the following elements, the one that forms cations with varying positive charges is:a. iron, Fe b. sodium, Na c. aluminum, Al

d. strontium, Sr e. nitrogen, N

48. Which of the following statements is incorrect?:a. metals generally form cations b. nonmetals are generally poor conductors of electricity c. metals are malleable d. nonmetals are generally brittle e. metalloids are metals with some nonmetallic characteristics

49. Which of the following statements are true?a. It is easier to remove an electron from Na than from Na+. b. As the atomic number increases within a group of the representative elements, the

tendency is for first ionization energy to increase. c. All particles with the electron configuration [Ar]4s2 have the same ionization

energy. d. The first ionization energy of fluorine is greater than the first ionization energy of

oxygen. e. All are false


50. An element having the configuration [Xe]6s1 belongs to the Group:a. alkali metals b. halogens c. alkaline earth metals

d. None of thesee. noble gases


51. How many unpaired electrons are there in an atom of tin in its ground state?a. 4b. 0

c. 3 d. 2

e. 1

52. Of the following elements, which one is most likely to form an ion through the loss of two electrons?

a. strontium b. chlorine

c. aluminumd. sodium

e. sulfur

53. Which of the following particles has the greatest atomic radius?a. Al b. Si

c. S d. Al3+

e. P

54. Which of the following forms of electromagnetic radiation has the shortest wavelength?a. ultravioletb. radio waves

c. infrared d. visible light

e. microwaves

55. For which of the following transitions does the light emitted have the shortest wavelength?

a. n = 4 to n = 2 b. n = 2 to n = 1 c. n = 5 to n = 3

d. n = 4 to n = 3 e. n = 3 to n = 2

56. Researchers at Lawrence Berkeley National Lab have recently formed a new synthetic element with atomic number 118 and mass number 293. Which of the following elements would have chemical properties most similar to this new element?

a. Ir b. Xe

c. Ta d. Pb

e. S

BONDING


As atoms bond with each other, they _____________________ their potential energy, thus

creating more stable arrangements of matter. The force that holds two ________________

together is called a chemical bond. There are 3 types of bonding: ionic, ___________________,

and metallic. The number of valence electrons are easily found by looking up the group number

on the periodic table.

Group 1A (Li, Na, K, etc.): 1 valence electron

Group 2A (Be, Mg, Ca, etc.): ______ valence electrons

Group 3A (B, Al, Ga, etc.): 3 valence electrons

Group 4A (C, Si, Ge, etc.): 4 valence electrons

Group 5A (N, P, As, etc.): _______ valence electrons

Group 6A (O, S, Se, etc.): 6 valence electrons

Group 7A (F, Cl, Br, etc.): 7 valence electrons

Group 8A (He, Ne, Ar, etc.): 8 valence electrons (except He has _______ valence

electrons)

Recall the rules for drawing Lewis dot diagrams: Write the _____________________ of the

element. Put one dot for each valence electron. Don’t _____________ electrons up until you

have to.

Electron Configurations and Electron Dot Diagrams for Cations

Metals lose electrons to attain noble gas configuration. They make positive ions, ____________.

If we look at an electron configuration, it makes sense. Example: Sodium (Na), 1s22s22p63s1,

has _________ valence electron(s). The electron that is removed comes from the ____________

energy level. As a result of the loss of the electron, the sodium ion (Na+) has the following

electron configuration: 1s22s22p6

Calcium has 2 valence electrons. These will come off, forming a positive ion.

Unit 4 – Types of Bonding

Electron Configurations and Electron Dot Diagrams for Anions

Nonmetals gain electrons to attain noble gas configuration. This means they want a(n)

________________ of electrons, 8 electrons. They make negative ions, ___________________.

If we look at an electron configuration, it makes sense. Example: Sulfur (S), 1s22s22p63s23p4,

has _______ valence electrons and needs to gain 2 more to have an octet.

The sulfur ion (S-2) has the same electron configuration as a noble gas: 1s22s22p63s23p6

Phosphorous has 5 valence electrons. It will gain _________ electrons to fill the outer shell.

Stable Electron Configurations

All atoms react to achieve __________________ gas configuration. Noble gases, except He,

have 2 s electrons and 6 p electrons, totaling 8 valence electrons. They obey the

____________________ rule.

IONIC BONDING

Anions and cations are involved in ionic bonding and are held together by __________________

charges, electrostatic attraction. The bond is formed through the ______________________ of

electrons. Electrons are transferred to achieve noble gas configuration. Ionic bonds occur

between _________________ and nonmetals. All the electrons must be accounted for! A

compound that is composed of _______________ is called an ionic compound. Note that only

the arrangement of electrons has changed. Nothing about the atom’s nucleus has changed. Ionic

compounds have a _______________________ structure, a regular repeating arrangement of

ions in the solid. Even though the ions are ___________________ bonded to one another, ionic

compounds are __________________. Strong repulsion breaks crystal apart. The structure is

rigid. They have _______________ melting points because of strong forces between ions. They

also conduct electricity in the _________________ and dissolved states. Any compound that

conducts electricity when melted or dissolved in water is a(n) ___________________________.

How many valence electrons must an atom have in its outer energy level in order to be

considered stable?

The energy required to separate one mole of the ions of an ionic compound is called

____________________ energy, which is expressed as a negative quantity. The greater (that is,

the more negative) the lattice energy is, the ______________________ the force of attraction

58


between the ions. Lattice energy tends to be __________________________ for more-highly-

charged ions (those atoms that have more electrons to give or those atoms that can take more

electrons). Lattice energy also tends to be greater for __________________ ions.

Between the following ionic compounds, which would be expected to have the higher

(more negative) lattice energy? LiF or KBr

Between the following ionic compounds, which would be expected to have the higher

(more negative) lattice energy? NaCl or MgS

The electronegativity difference for two elements in an ionic compound is greater than or equal

to _______________.

COVALENT BONDING

A _______________________ is an uncharged group of two or more atoms held together by

covalent bonds. Covalent compounds occur between two ___________________ or a nonmetal

and hydrogen. The attraction of two atoms for a shared _______________ of electrons is called

a covalent bond. In a covalent bond, atoms share electrons and neither atom has an ionic

______________________. Covalent bonds occur between 2 ___________________________

because nonmetals hold onto their valence electrons. They can’t give away electrons to bond,

yet, they still want _______________ gas configuration. They get it by sharing valence

electrons with each other. By sharing both atoms get to count the electrons toward noble gas

configuration. A ____________________ bond is formed from the sharing of two valence

electrons. The electronegativity difference for two elements in a covalent compound is between

_________ and 1.7.

Do atoms that share a covalent bond have an ionic charge?

Sometimes atoms share more than one pair of valence electrons. A ____________________

bond is when atoms share two pair of electrons, 4 electrons. A triple bond is when atoms share

three pair of electrons, _____ electrons. Triple bonds are ________________________ and

shorter than double bonds. Double bonds are stronger and shorter than

______________________ bonds.

59


THE WETTER WAY

You can easily determine the number of bonds in a compound by performing the “Wetter Way.”

# bonds = (Σe- after – Σe- before ) / 2

The number of electrons before bonding is equal to the __________________________ number.

To get the number of electrons after bonding, double the number of electrons before bonding,

BUT DO NOT EXCEED ___________!

Example: CO2 C is in column 4A and therefore has 4 valence electrons before bonding. O is

in column 6A and therefore has 6 valence electrons before bonding.

Σ electrons before bonding

Carbon = 4

Two oxygens = 6 x 2 = 12 (The formula CO2 implies there are 2 oxygen atoms.)

Σ electrons before bonding = 4 + 12 = 16

Σ electrons after bonding

C has 4 valence e- before bonding, so it has (4x2) = 8 electrons after bonding

O has 6 valence e- before bonding, so it has (6x2) = 12 electrons after bonding

Remember 8 is the maximum electrons after bonding, so oxygen can only have 8 electrons even

though we calculated 12.

Carbon = 8

Two oxygens = 8 x 2 = 16

Σ electrons after bonding = 8 + 16 = 24

# bonds = (Σe- after – Σe- before) / 2 = (24 - 16) / 2 = 4 bonds

The element you have only 1 of goes in the center. The other elements surround it. Connect the

elements with a single line (a single bond). You have only used 2 of your calculated 4 bonds, so

you need to double up. A line represents 2 electrons. Count your lines for each element to

determine if extra electrons need to be added. Carbon has 4 lines attached which represent 8

electrons. No extra electrons are needed around carbon. Each oxygen has 2 lines attached which

represent 4 electrons. Oxygen needs 8 electrons after bonding, so each oxygen needs 4 electrons.

Determine the number of bonds and draw the dot-dash diagram for HBr.

Determine the number of bonds and draw the dot-dash diagram for N2.

60


METALLIC BONDING

The bonding in metals is explained by the _______________________ ____________ model,

which proposes that the atoms in a metallic solid contribute their valence electrons to form a

“sea” of electrons that surrounds metallic __________________. These delocalized electrons

are not held by any specific atom and can ________________ easily throughout the solid. Metal

atoms release their valence electrons into a sea of electrons shared by all of the metal atoms. The

bond that results from this _____________________ pool of valence electrons is called a

metallic bond. Metals hold onto their valence electrons very _______________________.

Think of them as positive ions floating in a sea of electrons. Because electrons are free to move

through the solid, metals conduct _______________________. Metals generally have extremely

______________ melting points because it is difficult to pull metal atoms completely away from

the group of cations and attracting electrons. Metals are ________________________ (able to

be hammered into sheets). Metals are also ________________________ (able to be drawn into

wire) because of the mobility of the particles. Electrons allow atoms to slide by. A mixture of

elements that has metallic properties is called a(n) _____________________.

Homework / PracticeComplete the table by identifying the charge of each of the elements listed and then indicating

the formula for ionic compounds formed between the two substances

Charge O N P S Cl F

Charge 2-

Na 1+ Na2O

Mg

Ca

Al

Li

Zn

What type of boding is present in the following compounds:

1) SbBr3

2) Ag3) MgBr2

4) ClO2

5) KCl6) Fe

7) PbO8) FeCl2

61


What type of boding is present in the following compounds:

9) NI3

10) CO2

11) Ni

12) Au13) LiF14) Al2O3

15) N2O3

16) Mg3P2

17) CCl4

18) H2O

POLARITY and VSEPR

How each atom fares in a tug-of-war for shared electrons is determined by comparing the

_________________________________ of the two bonded atoms. Recall that electronegativity

is the measure of the ability of an atom in a bond to ________________________ electrons.

Atoms with large electronegativity values, such as fluorine, attract shared valence electrons more

__________________ than atoms such as sodium that have small electronegativities.

Electronegativity is a periodic property. With only a few exceptions, electronegativity

values_____________________ as you move from left to right in any period of the periodic

table. Within any group, electronegativity values decrease as you go ___________________

the group. Fluorine has the highest value of ____________. The greater the difference between

the electronegativities of the bonding atoms, the more _____________________________ the

electrons are shared and the more polar the bond.

If the electronegativity difference between the two elements in question is:

between 0.0 – 1.7, the bond is ______________________

greater than 1.7, the bond is _____________________

When the electronegativity difference in a bond is 1.7 or greater, the sharing of electrons is so

unequal that you can assume that the electron on the less electronegative atom is

________________________ to the more electronegative atom. For example, ∆EN for cesium

and fluorine is 4.0 − 0.7 = 3.3. Therefore the bond is _________________.

COVALENT BONDS AND POLARITY

When the atoms in a bond are the same, the electrons are shared ________________________.

This results in a _______________________ covalent bond. _________________________

elements (H2, O2, N2, Cl2, Br2, I2, F2 and At2) have pure nonpolar covalent bonds. All other

covalent bonds are polar. The electron sharing is not equal, but it is not so unequal that a

complete _____________________ of electrons takes place.

62


Consider hydrogen and chlorine. Hydrogen has an electronegativity of 2.20, and chlorine has an

electronegativity of 3.16. The ________ pulls harder on the electrons because its

electronegativity is greater. The electrons spend more time near the Cl. These symbols,

__________________ plus (δ+) and delta minus (δ-), represent a partial positive charge and a

partial negative charge.

Polar molecules are molecules with a positive and a negative ______________. This requires

two things to be true: The molecule must contain _______________ bonds. (This can be

determined from differences in electronegativity.) Symmetry cannot ______________________

out the effects of the polar bonds. (Must determine geometry first.)

In the following compounds, determine whether the molecule is polar or nonpolar

a. hydrogen fluoride (HF)

b. water (H2O)

c. carbon tetrachloride (CCl4)

d. ammonia (NH3)

e. carbon dioxide (CO2)

VSEPR

VSEPR stands for Valence Shell ______________________ ________________ Repulsion. It

predicts three-dimensional geometry of molecules. The valence shell includes the

______________________ electrons. The electron pairs try to get as far away as possible to

_______________________ repulsion. You can determine the angles of the bonds. VSEPR is

based on the number of pairs of valence electrons, both bonded and unbonded. An unbonded

pair of electrons is referred to as a _______________pair. Use the Wetter Way to calculate the

number of bonds and then draw the dot-dash diagram. The shape of the molecule and bond

angle can be determined from this diagram.

LINEAR

Consider the simplest molecule that exists—hydrogen, H2. Determine the number of bonds

using the Wetter Way.

H is in column 1A and therefore has 1 valence electron before bonding.

Σ electrons before bonding

Two hydrogens = 1 x 2 = 2

H – 1 valence e- before bonding, so it has (1x2) = 2 electrons after bonding

Σ electrons after bonding

63


Two hydrogens = 2 x 2 = 4

(4 – 2) / 2 = 1, so H2 has 1 bond!

Connect the elements with a single bond. You have used all of the calculated bonds.

Each hydrogen has 1 line attached which represents _______________ electrons. No extra

electrons are needed around hydrogen to have the 2 electrons needed after bonding.

A hydrogen molecule is linear. The electrons attempt to maximize their distance from one

another by having bond angle of ____________°. Linear compounds are NOT

____________________.

TETRAHEDRAL

Consider CH4. The Wetter Way shows that CH4 has __________ bonds! The element you have

only one of goes in the _______________________. The other elements surround it. Connect

the elements with a single _________________ (a single bond). You have used all 4 of your

calculated bonds. Remember a line represents ___________ electrons. Count your lines for

each element to determine if extra electrons need to be added. Carbon has 4 lines attached which

represent _________ electrons. No extra electrons are needed around carbon. Each hydrogen

atom has one line attached which represents 2 electrons. No extra electrons are needed around

hydrogen. Single bonds fill all atoms. There are _________ bond pairs of electrons pushing

away. The electrons can _________________ their distance from one another by forming a 3-D

shape. The furthest they can get away is ___________º. This basic shape is a tetrahedral, a

pyramid with a triangular base. The tetrahedral is the shape for everything with 4 bond pairs and

____________ lone pairs around the central atom.

TRIGONAL PYRAMIDAL

Perform the Wetter Way for phosphorous trichloride (PCl3). How many bonds are in this

molecule? ________ Sketch the dot-dash diagram for phosphorous trichloride. Please include

all electrons. Only the electrons around the ______________________ atom affect the shape.

The shape is a basic _______________________________ but you can’t see the lone pair. The

shape is called trigonal pyramidal. The bond angle is ____________° between the chlorines

because the electron pair forces the chlorines closer to each other.

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BENT

Perform the Wetter Way for water (H2O). How many bonds are in this molecule? _____ Sketch

the dot-dash diagram for water. Please include all electrons. Only the electrons around the

central atom affect the shape. The shape is still basic tetrahedral, but you can’t see the

_________ lone pairs. The shape is called bent. The bond angle between hydrogens is

____________°.

TRIGONAL PLANAR

Perform the Wetter Way for H2CO. How many bonds are in this molecule? _____ Sketch the

dot-dash diagram for H2CO. Please include all electrons. (Carbon is the central atom.) The

farthest you can get the elements apart is __________º. The shape is flat and called trigonal

planar.

Determine the number of bonds, draw the dot-dash diagram, state the VSEPR shape and

provide the bond angle for the following compounds

a. CO2 b. BCl3 c. SCl2 d. SiF4

HYBRID ORBITALS

Hybrid orbitals combine bonding with geometry. ______ hybridization has a linear shape. sp2

hybridization has a trigonal ____________________ shape. ____________ hybridization has

tetrahedral, trigonal pyramidal and bent shapes.

Homework/PracticeDraw the Lewis structure for each of the following compounds, identify the shape of the

molecule, and identify the polarity of the molecule.

1. CCl4

2. BF3

3. NF3

4. H2CS

5. SiO2

6. H2S

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INTERMOLECULAR FORCES

Intermolecular forces are forces of _______________________. They are what make solid and

liquid molecular compounds possible. The three intermolecular forces are _________________

bonds, dipole–dipole forces and London ____________________________ forces.

Hydrogen Bonding

A hydrogen bond is a _________________________________________ attraction that occurs

between molecules containing a hydrogen atom bonded to a small, highly electronegative atom

with at least ____________ lone electron pair. For a hydrogen bond to form, hydrogen must be

bonded to a fluorine, __________________________, or nitrogen atom. F, O, and N are very

electronegative so it is a very _______________________ dipole. Hydrogen bonding is the

_________________________ of the intermolecular forces. Examples include H2O, NH3, and

HF.

Dipole-dipole Forces

Polar molecules contain ___________________________ dipoles; that is, some regions of a

polar molecule are always ___________________________ negative and some regions of the

molecule are always partially positive. Attractions between _____________________________

charged regions of polar molecules are called dipole–dipole forces. Neighboring polar

molecules orient themselves so that oppositely charged regions _______________ up.

Opposites attract but are not completely hooked as in ionic solids. Dipole-dipole forces depend

on the number of _______________________. Bigger molecules result in more electrons, and

more electrons mean ________________________ forces. Dipole–dipole forces are stronger

than dispersion forces as long as the molecules being compared have approximately the same

mass. Examples of compounds that exhibit dipole-dipole forces include CO, HCl, and PH3.

London Dispersion Forces

Dispersion forces are ____________________ forces that result from temporary shifts in the

______________________ of electrons in electron clouds. Remember that the electrons in an

electron cloud are in constant _____________________. When two nonpolar molecules are in

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close contact, especially when they collide, the electron cloud of one molecule

_______________________ the electron cloud of the other molecule. The electron density

around each nucleus is, for a moment, greater in one region of each cloud. Each molecule forms

a __________________________ dipole. When temporary dipoles are close together, a weak

dispersion force exists between oppositely charged regions of the dipoles. Due to the temporary

nature of the dipoles, dispersion forces are the __________________________ intermolecular

force. Dispersion forces exist between ____________ gases and compounds that are nonpolar.

Examples include Ar, Cl2, Br2, CH4, and CO2. Dispersion forces ______________________ as

the mass of the molecule increases. C2H6 (MW = 30.0 g/mol) has stronger dispersion forces than

CH4 (MW = 16.0 g/mol). This difference in dispersion forces explains why fluorine and

chlorine are gases, bromine is a __________________________, and iodine is a solid at room

temperature. The molecular mass of iodine is greater than that of bromine, and bromine has a

greater mass than chlorine.

Intermolecular Forces

To determine what type of intermolecular force a compound has, ask yourself the following

questions.

Does the compound contain hydrogen attached to N, O, or F?

o If yes, the force is hydrogen bonding.

Determine the number of bonds from the Wetter Way and draw the dash-dot diagram.

Does the central element of the compound contain any lone pairs of electrons?

o If yes, the force is dipole-dipole.

Does the central element of the compound contain ZERO lone pairs of electrons?

o If yes, the force is dispersion.

Determine the type of intermolecular force in each of the following compounds

1) BCl3 _____________________________2) Xe _____________________________

3) NH3 _____________________________ 4) CH4 _____________________________

5) SO2 _____________________________ 6) H2 _____________________________

7) SO3 _____________________________ 8) CH3Cl ___________________________

9) HF _____________________________ 10) HBr ____________________________

67


Types of Bonding Practice Test1. In a complete sentence, compare and contrast metallic bonds and ionic bonds.

Directions- For each of the following pairs of elements, write the formula for the ionic compound that would form between them2. K and Cl3. Na and N4. Al and O

5. Calcium and Chlorine6. Zinc and Sulfur7. Lithium and Phosphorous

Directions- Draw the Lewis structure , Identify the shape of the molecule, Identify the polarity of the bonds, Identify the polarity of the molecule, Identify the IMF that would be exhibited

8. CCl4 9. SF2

10. SiO2

11. BI3

12. PCl3

13. N2

14. What does IMF stand for? Which of the three IMF’s is the weakest?


15. What type of bond exists between atoms of potassium and chloride in a crystal of potassium chloride?

a. Hydrogen bondb. Ionic bondc. Polar covalent bond

d. Nonpolar covalent bonde. Metallic bond

16. What type of bond exists between atoms in a nitrogen molecule?a. Hydrogen bondb. Ionic bondc. Polar covalent bond


17. What type of bond exists between atoms of calcium in a crystal of calcium?a. Hydrogen bondb. Ionic bondc. Polar covalent bond


18. All of the following have covalent bonds excepta. HClb. CCl4

c. H2Od. CsF

e. CO2

19. Which of the following atoms normally forms monatomic molecules?a. Clb. H

c. Od. N

e. He

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20. The complete loss of an electron of one atom to another atom with the consequent formation of electrostatic charges is said to be

a. Covalent bondingb. Polar covalent bonding

c. Ionic bondingd. Coordinate covalent bonding

21. When a metal atom combines with a nonmetal atom, the nonmetal atom willa. lose electrons and decrease in size b. lose electrons and increase in size c. gain electrons and decrease in size d. gain electrons and increase in size

22. Which formula represents a molecular substance?a. CaO b. CO

c. Li2O d. Al2O3

23. Which combination of atoms can form a polar covalent bond?a. H and H b. H and Br

c. N and N d. Na and Br

24. Fluorine atoms tend to.______.when they form chemical compounds with metals. a. lose electrons b. gain electrons c. neither lose nor gain electrons...they usually share electrons equally with metals. d. Fluorine atoms do not form compounds with other atoms...fluorine is an inert gas.

25. What is a compound composed of?a. two or more different elements that are physically combined in a fixed proportionb. two or more different mixtures that are physically combined in a fixed proportionc. two or more different elements that are chemically combined in a fixed proportiond. two or more different elements that are chemically combined in a variable

proportion

26. How can a chemical compound be broken?a. can be broken down by physical meansb. can be broken down by chemical meansc. cannot be broken downd. can be broken down by physical or chemical means

27. Which of the following compounds is most likely to be ionic?a. CO2 b. CCl4

c. FeCl3

d. MgCl2 e. HBr

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28. How many unshared electron pairs must be included in the Lewis structure for water, H2O?

a. 3 b. 2

c. 1 d. 4

e. 0

29. Nitrogen triiodide, NI3, is an unstable molecule that is used as a contact explosive. Its molecular structure is:

a. none of theseb. octahedral c. square planar

d. tetrahedral e. pyramidal

30. In which of the following compounds does the bond between the central atom and chlorine have the greatest ionic character?

a. BCl3 b. FeCl2

c. CCl4 d. HCl

e. CaCl2

31. Which of the following molecules must contain at least one double bonda. H2Ob. CCl4 c. H2O2

d. CH3I e. CH3COOH

32. The Lewis structure for hydrogen cyanide is:

a.

b.

c.

d.

e.

33. In the Lewis structure for CH2Cl2, the number of unshared electron pairs is:a. 10b. 8

c. 2 d. 4

e. 6

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34. The only intermolecular forces existing between oxygen molecules are:a. ion-ion attractive forces b. hydrogen bonding forces c. permanent dipole forces

d. nuclear forcese. London dispersion forces

35. Reactions between alkali metals and phosphorous result in compounds with the formula:

a. M3P b. None of thesec. M2P

d. M2P3 e. MP3

36. Which of the following arrangements represent ions?

i. 12 protons, 12 neutrons, 11 electrons ii. 12 protons, 11 neutrons, 12 electrons

iii. 11 protons, 12 neutrons, 12 electrons iv. 11 protons, 12 neutrons, 11 electrons v. 12 protons, 12 neutrons, 12 electrons

a. 1 and 2 b. 1, 3, and 4 c. 1 and 3

d. 2 and 3 e. all of these are ions

37. A particle X contains 10 electrons, seven neutrons and has a net charge of 3-. The particle is:

a. a nitride ion b. obviously polyatomic c. an oxide ion

d. a neon ion e. none of these are correct

38. Ions are formed in chemical reactions by:i. Gaining electrons

ii. Losing electrons iii. Gaining protons iv. Losing protons v. All of these

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a. 1 and 2 are correct b. 3 and 4 are correct c. 5 is correct

d. 1 and 3 are correct e. 2 and 4 are correct

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Unit 5 – Nomenclature

NAMING COMPOUNDS AND WRITING FORMULAS

Recall that the periodic table is more than a list of elements. Elements are put in columns

because of _____________________ properties. Each column is called a group. A compound is

made of two or more ______________________. The name should tell us how many and what

type of atoms. There are two types of compounds: ___________________ compounds and

molecular compounds. The simplest ratio of the ions represented in an ionic compound is called

a ______________________ unit. The overall charge of any formula unit is

________________. In order to write a correct formula unit, one must know the charge of each

ion. Atoms are electrically _____________________. They have the same number of protons

and electrons. ________________ are atoms, or groups of atoms, with a charge. Ions have a

different numbers of electrons. An anion is a _____________________ ion. An anion has

gained electrons. Nonmetals can ________________ electrons. The charge is written as a

superscript on the right. F1- has gained _________ electron. O2- has gained __________

electrons. A ___________________ is a positive ion. It is formed by __________________

electrons. There are more _____________________ than electrons. ______________________

form cations. K1+ has lost one electron. Ca2+ has lost __________ electrons. The charges of

monatomic ions, or ions containing only one atom, can often be determined by referring to the

periodic table or table of common ions based on group number. The charge of a monatomic ion

is equal to its _________________________ number. For most of the Group ________

elements, the Periodic Table can tell what kind of ion they will form from their location.

Elements in the same group have similar properties, including the charge when they are ions.

NAMING CATIONS

We will use the systematic way. For cations, if the charge is always the same (Group A) just

write the _________________ of the metal. Transition metals (as well as tin and lead) can have

more than one type of charge. The charge is indicated with ___________________ numerals in

parenthesis. Zinc (Zn2+) and silver (Ag1+), although transition metals, only have __________

possible charge. Roman numerals ARE NOT used for zinc and silver. Li1+ is called the

____________________ ion. __________ is called the Strontium ion. Fe2+ is called the Iron

(II) ion. Iron is a transition metal, so the charge is not always the same. The name of the metal

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is written, and the charge is denoted with Roman numerals in parenthesis. Pb2+ is called the Lead

__________ ion.

Name the following cations.

a) Ca2+ _________________________ b) Al3+ ___________________________

c) Sn4+ _________________________ d) Na+ _________________________

e) Fe3+ _________________________ f) Cu+ _________________________

WRITING FORMULAS FOR CATIONS

Write the formula for the metal. If a Roman numeral is in parenthesis use that number for the

_____________________. Indicate the charge with a superscript. If no Roman numeral is

given, find the Group A metal on the periodic table and determine the charge from the

_____________________ number. The formula for the nickel (II) ion is Ni2+. The formula for

the gallium ion is ____________.

Write the formulas for the following cations.

a) magnesium ion ________________ b) copper (II) ion ___________________

c) potassium ion ________________ d) silver ion _________________

e) chromium (VI) ion ________________ f) mercury (II) ion ________________

NAMING ANIONS

Naming monatomic anions is always the same. Change the element ending to – ___________.

F is the symbol for fluorine, F1- is fluoride. Cl1- is called the chloride ion. _______ is called the

oxide ion.

Name the following anions.

a) S2- _________________________ b) Br1- ___________________________

c) N3- _________________________ d) As3- _________________________

e) Te2- _________________________

WRITING FORMULAS FOR ANIONS

Write the formula for the nonmetal. Find the Group A nonmetal on the periodic table and

determine the charge from the column number.

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Write the formulas for the following anions.

a) iodide ion ________________ b) phosphide ion ___________________

c) selenide ion ________________ d) carbide ion _________________

IONIC COMPOUNDS

Oxidation numbers can be used to determine the chemical formulas for ionic compounds. If the

oxidation number of each ion is _________________________ by the number of that ion present

in a formula unit, and then the results are added, the sum must be _______________. In the

formula for an ionic compound, the symbol of the _________________ is written before that of

the anion. Subscripts, or small numbers written to the lower ______________________ of the

chemical symbols, show the numbers of ions of each type present in a formula unit.

BINARY IONIC COMPOUNDS

Binary ionic compounds are composed of a metal bonded with a ________________________.

Name the metal ion using a Roman numeral in parenthesis if necessary. Follow this name with

the name of the nonmetal ion.

Name the following binary ionic compounds.

a) NaCl __________________ b) Ca3P2 __________________

c) CuO __________________ d) SnBr2 __________________

e) Fe2S3 __________________ f) AlF3 __________________

g) KCl __________________ h) Na3N __________________

i) CrN __________________ j) PbO2 __________________

Write the symbol for the metal. Determine the oxidation number from either the column number

or the Roman numeral and write it as a superscript to the right of the metal’s symbol. To the

right of the metal’s symbol, write the symbol for the nonmetal. Determine the oxidation number

from the column number and write it as a superscript to the right of the nonmetal’s symbol.

Example: potassium fluoride - K1+ F1- If the two oxidation numbers add together to get

zero, the formula is a one-to-one ratio of the elements. Answer = KF

Example: aluminum sulfide - Al3+ S2- If the two oxidation numbers DO NOT add

together to get zero, you will need to “criss-cross” the superscripts. These numbers now

75


become subscripts. Omit all positive and negative signs and omit all 1’s. Answer =

Al2S3

Write the formulas for the following binary ionic compounds.

a) lithium selenide __________________ b) tin (II) oxide __________________

c) tin (IV) oxide __________________ d) magnesium fluoride ________________

e) copper (II) sulfide __________________ f) iron (II) phosphide _________________

g) gallium nitride __________________ h) iron (III) sulfide __________________

TERNARY IONIC COMPOUNDS

Ternary ionic compounds are composed of at least _________ elements. Name the metal ion,

using a Roman numeral in parenthesis if necessary. Follow this name with the name of the

polyatomic ion. Polyatomic ions are groups of atoms that stay together and have a

__________________. Examples are provided on page 7 of the NCDPI Reference Tables for

Chemistry. There is one polyatomic ion with a positive oxidation number (NH4+) that may come

first in a compound. Name the ion. Follow this name with the name of the anion or second

polyatomic ion. Certain polyatomic ions, called ________________________, contain oxygen

and another element.

Name the following ternary ionic compounds.

a) LiCN __________________ b) Fe(OH)3 ___________________

c) (NH4)2CO3 __________________ d) NiPO4 __________________

e) NaNO3 __________________ f) CaSO4 __________________

g) (NH4)2O __________________ h) CuSO3 __________________

Write the symbol for the metal or ammonium ion. Write the oxidation number as a superscript to

the right of the metal’s/ammonium ion’s symbol. To the right of the metal’s symbol, write the

symbol for the nonmetal or polyatomic ion. Write the oxidation number as a superscript to the

right of the nonmetal’s/polyatomic ion’s symbol.

Example: potassium nitrate - K1+ NO31- If the two oxidation numbers add together to get

zero, the formula is a one-to-one ratio of the elements. Answer = KNO3

Example: aluminum hydrogen sulfate – Al3+ HSO4 1- If the two oxidation numbers DO NOT

add together to get zero, you will need to “criss-cross” the superscripts. These numbers now

76


become subscripts. Parentheses are to be placed around polyatomic ions before criss-

crossing. Omit all positive and negative signs and omit all 1’s. Answer = Al(HSO4)3

Write the formulas for the following ternary ionic compounds.

a) ammonium chloride __________________ b) ammonium sulfide _________________

c) barium nitrate __________________ d) zinc iodate __________________

e) sodium hypochlorite __________________ f) chromium (III) acetate ______________

g) iron (II) dichromate __________________ h) mercury (I) bromate ________________

MOLECULAR COMPOUNDS

Molecular compounds are made of molecules. They are made by joining

_______________________ atoms together into molecules. A molecular compound’s name

tells you the number of atoms through the use of ____________________________.

1 mono- 4 tetra- 7 hepta- 10 deca-

2 di- 5 penta- 8 octa-

3 tri- 6 hexa- 9 nona-

The name will consist of two words. Prefix name prefix name –ide One exception is we

don’t write mono- if there is only one of the first element. The following double vowels cannot

be used when writing names: (oa) and (oo).

Example: NO2 There is one nitrogen. Mononitrogen But, you cannot use mono- on the

first element, so drop the prefix. There are two oxygens. dioxygen You need the suffix –

ide. dioxide Answer: nitrogen dioxide.

Example: N2O There are two nitrogens. Dinitrogen There is one oxygen. monooxygen

You cannot run (oo) together, so monoxygen. You need the suffix –ide. monoxide

Answer: dinitrogen monoxide.

Name the following molecular compounds.

a) Cl2O7 ____________________________ b) CBr4 ____________________________

c) CO2 ________________________ d) BCl3 ___________________________

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When writing a formula of a molecular compound from the name, you will not need to criss-

cross oxidation numbers. Molecular compounds name tells you the number of atoms through the

use of prefixes.

Example: diphosphorus pentoxide The name implies there are 2 phosphorous atoms and

5 oxygens. Answer: P2O5

Example: sulfur hexafluoride The name implies there is 1 sulfur atom and 6 fluorines.

Answer: SF6

Write the formulas for the following molecules.

a) tetraiodide nonoxide __________________ b) nitrogen trioxide __________________

c) carbon tetrahydride __________________ d) phosphorus trifluoride ______________

IONIC MOLECULAR

Smallest Piece Molecule

Types of

Elements

metal and nonmetal

State of Matter solid

Melting Point Low <300°C

ACIDS

Acids are compounds that give off hydrogen ions (H+) when dissolved in water. Acids will

always contain one or more hydrogen ions next to an anion. The anion determines the name of

the acid.

Binary Acids

Binary acids contain hydrogen and an anion whose name ends in –ide. When naming the acid,

put the prefix hydro- and change -ide to -ic acid.

Example: HCl The acid contains the hydrogen ion and chloride ion. Begin with the

prefix hydro-, name the nonmetallic ion and change -ide to -ic acid. Answer:

hydrochloric acid

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Example: H2S The next step is change -ide to -ic acid, but for sulfur the “ur” is added

before -ic. Answer: hydrosulfuric acid

Name the following binary acids.

a) HF ____________________________ b) H3P ____________________________

The prefix hydro- lets you know the acid is binary. Determine whether you need to criss-cross

the oxidation numbers of hydrogen and the nonmetal.

Example: hydrobromic acid The acid contains the hydrogen ion and the bromide ion.

H1+ Br1- The two oxidation numbers add together to get zero. Answer: HBr

Example: hydrotelluric acid The acid contains the hydrogen ion and the telluride ion.

H1+ Te2- The two oxidation numbers do NOT add together to get zero, so you must

criss-cross. Answer: H2Te

Write the formulas for the following binary acids.

a) hydrocyanic acid __________________ b) hydroselenic acid __________________

Ternary Acids

The acid is a ternary acid if the anion has oxygen in it. The anion ends in -ate or -ite. Change

the suffix -ate to -ic acid. Change the suffix -ite to -ous acid. The hydro- prefix is NOT used!

Example: HNO2 The acid contains the hydrogen ion and nitrite ion. Name the

polyatomic ion and change -ite to -ous acid. Answer: nitrous acid

Example: H3PO4 The acid contains the hydrogen ion and phosphate ion. Name the

polyatomic ion and change -ate to -ic acid. Answer: phosphoric acid

Name the following ternary acids.

a) H2CO3 ____________________________ b) H2SO4 __________________________

c) H2CrO4 ________________________ d) HClO2 __________________________

The lack of the prefix hydro- from the name implies the acid is ternary, made of the hydrogen

ion and a polyatomic ion. Determine whether you need to criss-cross the oxidation numbers of

hydrogen and the polyatomic ion.

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Example: acetic acid The polyatomic ion must end in –ate since the acid ends in -ic.

The acid is made of H+ and the acetate ion. H1+ C2H3O21- The two charges when

added equal zero. Answer: HC2H3O2

Example: sulfurous acid Again the lack of the prefix hydro- implies the acid is ternary,

made of the hydrogen ion and a polyatomic ion. The polyatomic ion must end in –ite

since the acid ends in -ous. The acid is made of H+ and the sulfite ion. H1+ SO32-

The two charges when added do not equal zero, so you must crisscross the oxidation

numbers. Ignore the negative sign and ones are understood. Answer: H2SO3

Write the formulas for the following binary acids.

a) perchloric acid __________________ b) iodic acid __________________

c) dichromic acid __________________ d) hypochlorous acid ________________

Homework / PracticeName each of the following compounds

1. CuS

2. FeI2

3. Cu2SO4

4. CuCl2

5. Ni(C2H3O2)2

6. MnO

7. CoO

8. Mn2O3

9. Co2S3

10. AuF

11. CrBr2

12. AlPO4

13. KNO2

14. CaCO3

15. Mg(OH)2

16. Na2CrO4

17. Ba(CN)2

18. K2SO4

19. NH4NO3

20. FePO4

21. SbBr3

22. Ag

23. MgBr2

24. ClO2

25. KCl

26. Fe

27. PbO

28. FeCl2

29. NI3

30. CO2

31. Ni

32. Au

33. LiF

34. Al2O3

35. N2O3

36. Mg3P2

37. CCl4

38. H2O

39. NH4Cl

40. Fe(NO3)3

41. TiBr3

42. Cu3P

43. SnSe2

44. GaAs

45. Pb(SO4)2

46. Be(HCO3)2

47. Mn2(SO3)3

48.Al(CN)3

49. P4O6

50. N2O3

51. N2O

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52. BrO3

53. SiF4

54. P4S10

55. Cl2O3

56. PCl3

57. PF5

58. P2O5

59. Cl2O

60. CCl4

61. N2O5

62. As4O6

63. N2O4

64. NI3

65. ClF3

66. I2O5

Write the formula for each of the following compounds

67. iron (II) chloride

68. copper (I) sulfide

69. mercury (I) bromide

70. chromium (III) oxide

71. gold (I) iodide

72. manganese (II) nitride

73. cobalt (III) phosphide

74. iron (III) chloride

75. copper (II) sulfide

76. manganese (III) chloride

77. potassium perchlorate

78. aluminum sulfate

79. iron (II) carbonate

80. barium iodate

81. magnesium phosphate

82. silver phosphate

83. cobalt (III) nitrite

84. ammonium sulfite

85. dihydrogen oxide

86. lithium Iodide

87. silver chloride

88. carbon monoxide

89. selenium difluoride

90. calcium sulfide

91. silicon diselenide

92. diphosporus trioxide

93. iron (III) chloride

94. ,magnesium fluoride

95. zinc oxide

96. arsenic tribromide

97. carbon dioxide

98. gold (III) chlorite

99. silver dichromate

100. barium Iodide

101. carbon tetrafluoride

102. sodium sulfide

103. chromium (VI) phosphate

104. vanadium (IV) carbonate

105. tin (II) nitrite

106. cobalt (III) oxide

107. titanium (II) acetate

108. vanadium (V) sulfide

109. chromium (III) hydroxide

110. lithium iodide

111. lead (II) nitride

112. silver bromide

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Write the formula for the compound formed between the two ions listed

carbonate chromate chlorate sulfide chloride sulfite

sodium Na2CO3 Na2CrO4 · · · ·

silver · · · · · ·

ammonium · · · · · ·

Tin (II) · · · · · ·

magnesium · · · · · ·

lead (II) · · · · · ·

aluminum · · · · · ·

manganese (III) · · · · · ·

potassium · · · · · ·

barium · · · · · ·

APPLICATIONS OF THE MOLEMolar Mass

The molar mass of a compound is the mass of a mole of the

_________________________________ particles of the compound. Because each

representative particle is composed of two or more atoms, the molar mass of the compound is

found by adding the molar masses of all of the ________________ in the representative particle.

To determine the molar mass of an element, find the element’s symbol on the periodic table and

round the mass so there is __________ digit beyond the decimal. For example, the molar mass of

carbon (C) is ____________ g/mol, of chlorine (Cl) is ___________ g/mol and of iron (Fe) is

_____________ g/mol. In the case of NH3, the molar mass equals the mass of one mole of

nitrogen atoms plus the mass of ___________ moles of hydrogen atoms.

Molar mass of NH3 = molar mass of N + 3 (molar mass of H)

Molar mass of NH3 = 14.0 + 3 (1.0) = 17.0 g/mol

Mole Conversions

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You can use the molar mass of a compound to convert between mass and moles, just as you used

the molar mass of elements to make these conversions.

How many moles of magnesium in 56.3 g of Mg?

How many moles are in 146 grams of NH3?

How many moles are in 295 grams of Cr(OH)3?

How many moles are in 22.5 grams of HCl?

How many grams of sodium chloride in 3.45 moles of NaCl?

How many grams are in 0.120 moles of AlF3?

How many grams are in 13.0 moles of H2SO4?

How many grams are in 1.6 moles of K2CrO4?

Percent Composition

Recall that every chemical compound has a definite composition - a composition that is always

the same wherever that compound is found. The composition of a compound is usually stated as

the percent by mass of each element in the compound. The percent of an element (X) in a

compound can be found in the following way.

Determine the percent composition of chlorine in calcium chloride (CaCl2). First,

analyze the information available from the formula. A mole of calcium chloride consists

of one mole of calcium ions and ___________ moles of chloride ions. Next, gather

molar mass information from the atomic masses on the periodic table. To the mass of

one mole of CaCl2, a mole of calcium ions contributes ______________ g, and two

moles of chloride ions contribute 2 x 35.5 g = 71.0 g for a total molar mass of

111.1 g/mol for CaCl2. Finally, use the data to set up a calculation to determine the

percent by mass of an element in the compound.

Determine the percent composition of carbon in sodium acetate (NaC2H3O2).

Calculate the percent composition aluminum of aluminum oxide (Al2O3).

Determine the percent composition of oxygen in magnesium nitrate, which has the

formula Mg(NO3)2.

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Determine the percent composition of sulfur in aluminum sulfate, which has the formula

Al2(SO4)3.

Determine the percent composition of oxygen in zinc nitrite, which has the formula

Zn(NO2)2.

Percent Water in a Hydrate

Hydrates are compounds that incorporate ________________________ molecules into their

fundamental solid structure. In a hydrate (which usually has a specific crystalline form), a

defined number of water molecules are associated with each formula unit of the primary

material. Gypsum is a hydrate with __________ water molecules present for every formula unit

of CaSO4. The chemical formula for gypsum is CaSO4 • 2 H2O and the chemical name is calcium

sulfate __________________. Note that the dot in the formula (or multiplication sign) indicates

that the waters are there.

Other examples of hydrates are: lithium perchlorate trihydrate - LiClO4 • 3 H2O;

magnesium carbonate pentahydrate - MgCO3 • 5 H2O;

and copper (II) sulfate pentahydrate - CuSO4 • 5 H2O.

The water in the hydrate (referred to as "water of hydration") can be removed by heating the

hydrate. When all hydrating water is removed, the material is said to be

__________________________ and is referred to as a(n) ___________________________.

Experimentally measuring the ________________________ water in a hydrate involves first

heating a known mass of the hydrate to remove the waters of hydration and then measuring the

mass of the anhydrate remaining. The difference between the two masses is the mass of water

_______________. Dividing the mass of the water lost by the original mass of hydrate used is

equal to the fraction of water in the compound. Multiplying this fraction by ___________ gives

the percent water.

Determine the percent water in CuSO4 • 5 H2O (s).

Determine the percent water in MgCO3 •5 H2O (s).

Determine the percent water in LiClO4 • 3 H2O (s).

Empirical Formula

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You can use percent composition data to help identify an unknown compound by determining its

empirical formula. The empirical formula is the ________________________ whole-number

ratio of atoms of elements in the compound. In many cases, the empirical formula is the actual

formula for the compound. For example, the simplest ratio of atoms of sodium to atoms of

chlorine in sodium chloride is 1 atom Na : 1 atom Cl. So, the empirical formula of sodium

chloride is Na1Cl1, or NaCl, which is the true formula for the compound. The formula for

glucose is C6H12O6. The coefficients in glucose are all divisible by 6. The empirical formula of

glucose is CH2O.

Determine the empirical formula for Tl2C4H4O6.

Determine the empirical formula for N2O4.

The percent composition of an unknown compound is found to be 38.43% Mn, 16.80% C, and

44.77% O. Determine the compound’s empirical formula. Because percent means “parts per

hundred parts,” assume that you have ___________ g of the compound. Then calculate the

number of moles of each element in the 100 g of compound. To obtain the simplest whole-

number ratio of moles, _________________ each number of moles by the smallest number of

moles. Find the whole number mole ratio for the compound. These numbers become

the____________________________ in the empirical formula.

Determine the empirical formula of the following compound: 31.9 g Mg, 27.1 g P

The composition of an unknown acid is 40.00% carbon, 6.71% hydrogen, and

53.29% oxygen. Calculate the empirical formula for the acid.

The composition of an unknown ionic compound is 60.7% nickel and 39.3% fluorine.

Calculate the empirical formula for the ionic compound.

The composition of a compound is 6.27 g calcium and 1.46 g nitrogen. Calculate the

empirical formula for the compound.

Find the empirical formula for a compound consisting of 63.0% Mn and 37.0% O.

Molecular Formula

For many compounds, the empirical formula is not the true formula. A molecular formula tells

the ___________________ number of atoms of each element in a molecule or formula unit of a

compound. The molecular formula for a compound is either the same as the empirical formula

or a whole-number _______________________ of the empirical formula. In order to determine

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the molecular formula for an unknown compound, you must know the molar mass of the

compound in addition to its empirical formula. Then you can compare the molar mass of the

compound with the molar mass represented by the empirical formula.

The molecular mass of benzene is 78 g/mol and its empirical formula is CH. What is the

molecular formula for benzene? HINT: Calculate the molar mass represented by the

formula CH. Calculate the whole number multiple, n, and apply it to its empirical

formula.

The simplest formula for butane is C2H5 and its molecular mass is about 60.0 g/mol.

What is the molecular formula of butane?

What is its molecular formula of cyanuric chloride, if the empirical formula is CClN and

the molecular mass is 184.5 g/mol?

The simplest formula for vitamin C is C3H4O3. Experimental data indicates that the

molecular mass of vitamin C is about 180. What is the molecular formula of vitamin C?

Maleic acid is a compound that is widely used in the plastics and textiles industries. The

composition of maleic acid is 41.39% carbon, 3.47% hydrogen, and 55.14% oxygen.

HINT: Start by determining the empirical formula for the compound.

The composition of silver oxalate is 71.02% silver, 7.91% carbon, and 21.07% oxygen.

If the molar mass of silver oxalate is 303.8 g/mol, what is its molecular formula?

The composition of silver oxalate is 71.02% silver, 7.91% carbon, and 21.07% oxygen.

If the molar mass of silver oxalate is 303.8 g/mol, what is its molecular formula?

Homework / Practice

1) A compound is found to have (by mass) 48.38% carbon, 8.12% hydrogen and the rest oxygen. What is its empirical formula?

2) A compound is found to have 46.67% nitrogen, 6.70% hydrogen, 19.98% carbon and 26.65% oxygen. What is its empirical formula?

3) A compound is known to have an empirical formula of CH and a molar mass of 78.11 g/mol. What is its molecular formula?

4) Another compound, also with an empirical formula if CH is found to have a molar mass of 26.04 g/mol. What is its molecular formula?

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5) A compound is found to have 1.121 g nitrogen, 0.161 g hydrogen, 0.480 g carbon and 0.640 g oxygen. What is its empirical formula? (Note that masses are given, NOT percentages.)

6) A compound containing only carbon, hydrogen and oxygen is found to be 48.38% carbon and 8.12% hydrogen by mass. What is its empirical formula?

7) Phentyfloroform contains 57.54% C, 3.45% H, and 39.01% F. What is its empirical formula?

8) Calculate the empirical formula of the compound that contains 1.0 g S for each 1.5 g O.

9) Calculate the empirical formula of the compound containing 75.0% C and 25.0% H.10) Calculate the empirical formula of the compound containing 81.8% C and 18.2% H.11) The active ingredient in chocolate is theobromine; a sample was analyzed and determined to

be composed of: 147.0 g C 14.0 g H 56.0 g O 98.0 g N

a. Determine the % composition for each element.

b. Determine the empirical formula for theobromine.

c. The molecular weight of theobromine is known to be 180.0 g/mole. What is the molecular formula?

12) Determine the empirical formula of the compound containing 37.5% C, 12.5% H, and 50.0% O by weight.

13) Determine the empirical formula of the compound containing 26.1% C, 4.3% H, and 69.6% O by weight.

14) Determine the empirical formula of the compound containing 38.7% C, 16.1% H, and 45.2% N by weight.

15) What is the empirical formula of a compound if a 50.0 g sample of it contains 9.1 g Na, 20.6 g Cr, and 22.2 g O?

16) A compound was analyzed and found to contain 13.5 g Ca, 10.8 g O, and 0.675 g H. What is the empirical formula of the compound?

17) NutraSweet is 57.14% C, 6.16% H, 9.52% N, and 27.18% O. Calculate the empirical formula of NutraSweet and find the molecular formula. (The molar mass of NutraSweet is 294.30 g/mol)

18) A compound consists of 85% silver and 15% florine by mass. What is the empirical formula? 19) A compound consists of 40% calcium, 12% carbon, and 48% oxygen by mass. What is the

empirical formula by mass?20) A compound consists of 75% Magnesium, and 25% oxygen by mass. What is the empirical

formula by mass?21) A compound contains 50% Magnesium, 24% carbon, 16% oxygen, and 10% hydrogen. What

is the empirical formula?22) Phentyfloroform contains 57.54% C, 3.45% H, and 39.01% F. What is its empirical formula?

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23) Benzoic acid contains 68.8% Carbon, 4.95% Hydrogen and 26.2% Oxygen. Find the empirical formula?

24) Freons are gaseous compounds used in refrigeration. A particular freon contains 9.93% carbon, 56% chlorine, and 31.4% fluorine. What is the empirical formula?

Naming and Formula Math Practice TestDirections: Write the formula for the compound

1. sodium phosphide2. iron (II) perchlorate3. vanadium (V) nitrite4. nickel (I) oxide5. magnesium hydroxide

6. cesium nitride7. nitrogen trichloride8. hydroxic acid9. carbon tetrahydride

Directions: Name the compound

10. KCl11. FeSO4

12. Li2O

13. Cr2S3

14. Ca3N2

15. Fe2S3

16. CuI2

17. PBr3

18. CO2 19. HNO3

20. What is the percent nitrogen in potassium nitrate?

21. What is the ratio of barium ions to Nitrogen ions in a formula unit of barium nitrate?

22. A compound is found to have 46.67% nitrogen, 6.70% hydrogen, 19.98% carbon and

26.65% oxygen. What is its empirical formula?

23. A compound is found to have (by mass) 48.38% carbon, 8.12% hydrogen and the rest

oxygen. What is its empirical formula?

24. Phentyfloroform contains 57.54% C, 3.45% H, and 39.01% F. What is its empirical formula?

25. Determine the empirical formula of N3O6

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26. The empirical formula of a compound is CH2. Its molecular mass is 70g/mol. What is its

molecular formula? (Show all work.)

27. Determine the empirical formula of a compound that is 82% carbon, 18% hydrogen.

28. Determine the molecular formula of a compound that is composed of 40.0% carbon,

6.7% hydrogen and 53.5% oxygen. The molecular mass is 120.0g/mol.


29. Which of the following is a binary compound?a. hydrogen sulfide b. hydrogen sulfate

c. ammonium sulfide d. ammonium sulfate

30. What is the formula for sodium oxalate?a. NaClO b. Na2ClO

c. Na2C2O4 d. NaC2H3O2

31. Which of the following is a binary compound?a. potassium chloride b. ammonium chloride

c. potassium chlorate d. ammonium chlorate

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32. Which is the correct formula for nitrogen monoxide?a. NO b. N2O

c. NO2 d. N2O3

33. Which of the following represents the correct formula for aluminum oxide?a. AlOb. Al2O3

c. AlO2

d. Al2O

34. Which of the following is the correct name for NaHCO3?a. sodium hydrogen carbonateb. sodium acetatec. nitrogen hydrogen carbonated. sodium hydrogen carbon trioxide

35. In which of the following compounds does ionic bonding predominate?a. NH4Clb. CO2

c. CH4

d. LiBr

36. Which of the following molecules contains only one non-bonding pair of valence electrons?

a. NH4+

b. HCNc. C2H4

d. N2

37. What is the name of CaCl2?a. calcium dichlorideb. calcium (II) chloride

c. monocalcium dichlorided. calcium chloride

38. What is the name of Mg(NO3)2

a. Magnesium nitrateb. Magnesium (II) nitrate

c. Magnesium dinitrated. Magnesium nitrogen oxide

39. What is the name of P2O5?a. phosphorus oxideb. phosphorus pentaoxide

c. diphosphorus pentaoxided. phosphorus (III) oxide

40. What is the formula for sulfur hexachloride?a. S5Clb. SHCl

c. SCl5

d. SCl6

41. What is the name of the formula Fe(NO3)2?a. iron nitrateb. iron (II) nitrate

c. iron dinitrated. iron (III) nitrate

42. What is the formula for the compound nitrogen (II) oxide.a. N2O3 b. NO

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c. NO2 d. N2O

43. Which of the following is not a type of chemical formula?a. Empiricalb. Molecular

c. Structurald. Parabola

44. What is the approximate percentage oxygen in the formula mass of Ca(NO3)2?a. 28b. 42

c. 58d. 96

e. 164

45. Which formulas could represent the empirical formula and the molecular formula of a given compound?

a. CH2O and C4H6O4

b. CHO and C6H12O6

c. CH4 and C5H12

d. CH2 and C3H6

e. CO and CO2

46. When combining with nonmetallic atoms, metallic atoms generally willa. lose electrons and form negative ions b. lose electrons and form positive ions c. gain electrons and from negative ions d. gain electrons and form positive ions

47. What is the empirical formula of the compound whose molecular formula is P4O10?a. PO b. PO2

c. P2O5

d. P8O20

48. What is the percent by mass of oxygen in magnesium oxide, MgO?a. 20% b. 40%

c. 50% d. 60%

49. A compound is 86% carbon and 14% hydrogen by mass. What is the empirical formula for this compound?

a. CH b. CH2

c. CH3 d. CH4

50. What is the percent by mass of water in the hydrate Na2CO3 * 10H2O (formula mass = 286)?

a. 6.89% b. 14.5%

c. 26.1% d. 62.9%

51. What is the gram formula mass of (NH4)3PO4?

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a. 113 g b. 121 g

c. 149 g d. 404 g

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52. What is the empirical formula of a compound that contains 85% Ag and 15% F by mass?

a. AgF b. Ag2F

c. AgF2 d. Ag2F2

53. What is the percent water in hydrated calcium chloride... CaCl2·2H2O?a. 66.67%b. 32.47%

c. 24.51%d. 12.26%

54. What is the empirical formula for a compound that contains 17.34% hydrogen and 82.66% carbon?

a. C5Hb. C2H5

c. CH3

d. CH2

55. What is the molecular formula for a compound that is 46.16% carbon, 5.16% hydrogen and 48.68% fluorine if the molar mass of this compound is 156.12 g?

a. C3H4F2

b. C5H10F5

c. C6H8F4

d. C6H6F3

56. One mole of (NH4)2HPO4 contains _?_ moles of hydrogen atoms.a. 1 b. 5 c. 6 d. 9

57. Which of the following is named incorrectly?a. H2CO2 : carbonous acid b. HClO2 : chlorous acid c. H2SO4 : sulfuric acid

d. HClO : hydrochlorous acid e. H3PO3 : phosphorous acid

58. The name for the compound NaHSO4 is:a. sodium hydrogen sulfate b. sodium persulfate c. sodium bisulfate

d. two of these are correct e. none of these is correct

59. A sample of an alcohol is tested and found to contain 52% carbon, 35% oxygen, and 13% hydrogen by mass. Tests indicate that the molecular weight of the molecule is between 30 and 80. What is the molecular formula of the alcohol?

a. C2H5OH b. C3H7OH c. C5H11OH

d. C4H9OH e. CH3OH

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60. A 5.15 gram sample of a hydrocarbon is burned in oxygen, producing 15.6 grams of carbon dioxide and 8.45 grams of water. Assuming an excess of oxygen, what is the empirical formula of the hydrocarbon?

a. CH4 b. C7H16 c. C9H20

d. C5H12 e. C3H8

61. For which of the following compounds does 0.400 mol have a mass of 12.8 grams?

a. CH3OHb. CH4 c. CCl4

d. CO2 e. C4H10

62. What is the molar mass of glucose, C6H12O6?

a. 18 g b. 220.17 gc. 12.01 g

d. 180.18 g e. 160.00 g

63. Methane, CH4, and ethane, C2H6 are both hydrocarbons that exist as gases at room conditions. How many grams of ethane contain the same number of molecules as 6.00 g of methane?

a. 0.374 grams b. 0.09 grams c. 2896 grams

d. 11.2 grams e. 80.5 grams

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Unit 6- Chemical Reactions

CHEMICAL REACTIONS

All chemical reactions have two parts: (1) A substance that undergoes a reaction is called a

__________________________. In other words, reactants are the substances you start with.

(2) When reactants undergo a chemical change, each new substance formed is called a

___________________________. In other words, the products are the substances you end up

with. The reactants turn into the products. Reactants → Products. In a chemical reaction, the

way atoms are joined is changed. Atoms aren’t __________________________ or destroyed.

Chemical reactions can be described several ways.

In a sentence: Copper reacts with chlorine to form copper (II) chloride.

In a word equation: Copper + chlorine → copper (II) chloride

The arrow separates the reactants from the products. The arrow reads “reacts to

________________.” The plus sign reads “_____________.” (s) after the formula implies the

substance is a ___________________. (g) after the formula implies the substance is a gas. (l)

after the formula implies the substance is a ______________________. (aq) after the formula

implies the substance is aqueous, a solid dissolved in _____________________. __________

used after a product indicates a gas, same as (g). ↓ used after a product indicates a

________________, same as (s). _____________ indicates a reversible reaction.

________________ or ________________ shows that heat is supplied to the reaction.

___________________ is used to indicate a catalyst used supplied, in this case, platinum. A

catalyst is a substance that ____________________ ____________ a reaction without being

changed by the reaction. Enzymes are biological or ______________________ catalysts.

There are seven elements that never want to be alone. They form ________________________

molecules.H2 , N2 , O2 , F2 , __________ , Br2 , I2. (1 + 7 pattern on the periodic table)

The following are indications that a chemical reaction has occurred: formation of a

____________________________, evolution of a gas, _____________________ change, and

absorption or release of ________________.

A ________________________ formula uses formulas and symbols to describe a reaction. All

chemical equations are sentences that describe reactions.

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Convert the following sentences to chemical equations.

a) Solid iron (III) sulfide reacts with gaseous hydrogen chloride to form solid iron (II)

chloride and hydrogen sulfide gas.

b) Nitric acid dissolved in water reacts with solid sodium carbonate to form liquid

water and carbon dioxide gas and sodium nitrate dissolved in water.

Convert the following chemical equations to sentences.

a) Fe (s) + O2 (g) → Fe2O3 (s)

b) Cu (s) + AgNO3 (aq) → Ag (s) + Cu(NO3)2 (aq)

Balancing Equations

Atoms can’t be ______________________ or destroyed. All the atoms we start with we must

end up with. A balanced equation has the same number of each element on both

_________________ of the equation. Example: C + O2 → CO This equation is NOT

balanced. There is one carbon atom on the left and ________ on the right. There are two

oxygen atoms on the left and only one on the right. We need one more oxygen atom in the

products. We can’t change the formula, because it describes what it is. In order to have two

oxygen atoms, another CO must be produced. But where did the other carbon come from? We

must have started with two carbon atoms. The balanced chemical equation is 2 C + O2 → 2 CO

Rules for Balancing

Write the correct formulas for all the reactants and products.

Count the number of atoms of each type appearing on both sides.

Balance the elements one at a time by adding coefficients (the numbers in front).

Check to make sure it is balanced.

Never change a _________________________ to balance an equation. If you change the

formula you are describing a different reaction. Never put a coefficient in the middle of a

formula. 2 NaCl is okay; Na2Cl is not.

Balance the following reaction. H2 + O2 → H2O

Balance elements in the following order: (1) metals; (2) nonmetals; (3) hydrogen; and (4)

oxygen

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If an atom appears more than once on a side, balance it last. If you fix everything except one

element, and it is even on one side and odd on the other, double the first number, then move on

from there.

Balance the following equations.

1) _____ CH4 + _____ O2 → _____ CO2 + _____ H2O

2) _____ AgNO3 + _____ Cu → _____ Cu(NO3)2 + ______ Ag

3) _____ Mg + _____ N2 → _____ Mg3N2

4) _____ P + _____ O2 → ______ P4O10

5) _____ Na + _____ H2O → _____ H2 + _____ NaOH

6) _____ Pb(NO3)2 + _____ K2CrO4 ® ______ PbCrO4 + ______ KNO3

7) _____ MnO2 + _____ HCl ® _____ MnCl2 + ______ H2O + _____ Cl2

8) _____ Ba(CN)2 + _____ H2SO4 ® _____ BaSO4 + _____ HCN

9) _____ Zn(OH)2 + _____ H3PO4 ® _____ Zn3(PO4)2 + _____ H2O

TYPES OF REACTIONS

Reactions fall into 5 categories. We will recognize the type by the reactants. We will be able to

predict the products. For some we will be able to predict whether they will happen at all.

Synthesis Reactions

Synthesize means to put together. Whenever two or more substances combine to form one single

product, the reaction is called a synthesis reaction.

Examples: Ca + O2 → CaO and P2O5 + 3 H2O → 2 H3PO4

We can predict the products if they are two elements. All you need to do is combine the

elements, metals first, and criss-cross oxidation numbers if necessary. After predicting the

product, the reaction must be balanced.

Mg + N2 →

CaO + H2O →

On page 6 of the Chemistry Reference Packet, this reaction is an example of “Metal oxide -

water reactions.” The product listed in the packet is “base.” A base is a metallic hydroxide.

SO2 + H2O →

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On page 6 of the Chemistry Reference Packet, this reaction is an example of “Nonmetal oxide -

water reactions.” The product listed in the packet is “________________.” The acid is a ternary

acid. Ternary acids start with _________ and end in O. The other element goes in the center.

This is the only compound for which you can add the number of elements and use these numbers

as subscripts.

Write and balance the following synthesis reactions.

a) Ca + Cl2 →

b) Fe + O2 → HINT: Use iron (II).

c) K2O + H2O →

d) Al + O2 →

e) SO3 + H2O →

f) N2O5 + H2O →

Decompositions Reactions

The word decompose implies the compound will “fall apart.” In a decomposition reaction, one

compound breaks down into _____________ or more simple substances.

NaCl → Na + Cl2

CaCO3 → CaO + CO2

We can easily predict the products if it is a binary compound. A binary compound is made up of

only two elements. The compound merely falls apart into its elements.

H2O →

HgO →

If the compound has more than two elements, you must consult the Reference Tables, page 6.

NiCO3 →

NiCO3 is called nickel (II) carbonate. The packet states that a metallic carbonate decomposes to

form a MO (metallic oxide) and CO2. The metallic oxide is nickel (II) oxide.

Use the Chemistry Reference Tables to write and balance the following decomposition

reactions.

a) KClO3 →

b) CaBr2 →

c) Li2CO3 →

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d) Cr(OH)2 →

e) NaHCO3 →

f) HNO3 → (Dinitrogen pentoxide one of the products.)

Single Replacement

In a single-displacement reaction, one element takes the place of another in a compound. One

reactant must be an element, and the one reactant must be a _______________________. The

products will be a different element and a different compound.

F2 + LiCl → LiF + Cl2

Remember zinc, Zn, always forms a ___________ ion doesn’t need parenthesis. ZnCl2 is zinc

chloride. In addition, silver, Ag, always forms a ___________ ion. AgCl is silver chloride.

Some single replacement reactions do not occur because some elements are not as

________________ as others. A more active element _________________________ a less

active element. There is a list referred to as the Activity Series on page 7 of your Chemistry

Reference Packet. A higher element on the list replaces lower element. If the element by itself

is lower on the list, the reaction will ___________ occur.

Metals replace metals (and hydrogen)

K + NaCl →

Potassium wants to replace ________________________. You must check the activity series on

page 7 of your Chemistry Reference Packet to see if this is possible. Because K is higher,

potassium can replace sodium. The potassium will bond with the _____________________ and

the sodium will be alone. You must always check to see if the compound formed needs criss-

crossing. Check for balancing.

Sn + FeCl3 →

Because Sn is NOT higher, tin cannot replace iron. No reaction occurs.

Write and balance the following single replacement reaction.

a) Rb + AlN →

b) Zn + HCl →

c) Ag + CoBr2 →

Metals replace hydrogen

Na + H2O (cold) →

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Think of water as HOH. Metals high enough on the activity series replace the first ______ and

combine with the OH1- (hydroxide) according to page 6 of the Reference Tables. Is sodium

above hydrogen and higher than the line marked “Replace hydrogen from cold water” on the

activity series? Since the answer is yes, sodium replaces the first H, bonding with hydroxide.

Mg + HCl →

Metals higher on the activity series replace the H and combine with the nonmetal according to

page 6 of the Reference Tables. Hydrogen gas is a second product. Is magnesium above

hydrogen on the activity series?

Write and balance the following single replacement reactions.

a) Ag + H2O (steam) →

b) Cu + H2SO4 →

c) Cr + H3PO4 → (HINT: Use Cr3+ )

d) Ca + H2O (steam) →

Nonmetals can replace other ________________________. This is limited to F2 , Cl2 , Br2 and I2

The order of activity is listed in the Chemistry Reference Packet, page 7. Higher replaces

_____________.

F2 + HCl →

Is fluorine above chlorine in the activity series of halogens? Since the answer is yes, fluorine

replaces the chlorine, bonding with hydrogen.

Write and balance the following single replacement reactions.

a) Br2 + KCl →

b) Cl2 + KI →

Double Replacement

In double-displacement reactions, the positive portions of two ___________________

compounds are interchanged. The reactants must be two ionic compounds or ______________.

Double replacement reactions usually take place in ________________________ solution.

NaOH + FeCl3 →

The positive ions change place. You must check to see if you need to criss-cross the products.

Now balance. A double replacement reaction will only happen if one of the products: (1)

doesn’t dissolve in water and forms a __________________, (2) is a _____________ that

bubbles out, or (3) is a _________________________ compound usually water.

3NaOH + FeCl3 → Fe(OH)3 + 3NaCl

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None of the products are familiar gases. Both products are ionic (not covalent) because they

start with metals. We must consult the Solubility Rules on page 6 of the Chemistry Reference

Tables to determine if a solid (a ________________________) is formed. The “Soluble” side of

the Solubility Rules states that Group 1 (IA) salts are soluble; therefore, NaCl is soluble and is

NOT the precipitate.

The “Insoluble” side of the Solubility Rules states that all hydroxides except Group 1, Sr, Ba and

NH41+ are INSOLUBLE. Therefore, Fe(OH)3 is the precipitate (solid). In molecular equations,

the formulas of the compounds are written as though all species existed as molecules or whole

units. An ionic equation shows dissolved ionic compounds in terms of their free ions. Ions that

are not involved in the overall reaction are called spectator ions. The net ionic equation indicates

only the species that actually take part in the reaction. The following steps are useful for writing

ionic and net ionic equations:

1) Write a balanced molecular equation for the reaction.

2) Rewrite the equation to indicate which substances are in ionic form in solution.

Remember that all soluble salts (and other strong electrolytes), are completely dissociated

into cations and anions. This procedure gives us the ionic equation.

3) Lastly, identify and cancel spectator ions on both sides of the equation to arrive at the net

ionic equation.

Example: sodium hydroxide + iron (III) chloride yields iron (III) hydroxide + sodium

chloride

Balanced Molecular Equation: 3 NaOH + FeCl3 Fe(OH)3 + 3 NaCl

Complete Ionic Equation:

3Na1+ + 3OH1- + Fe3+ + 3Cl1- Fe(OH)3 + 3Na1+ + 3Cl1-

Net Ionic Equation: 3OH1- + Fe3+ Fe(OH)3

Write and balance the following double replacement reaction. Assume the reaction takes

place. In addition, identify the precipitate and write the net ionic equation.

a) CaCl2 + NaOH →

b) CuCl2 + K2S →

c) KOH + Fe(NO3)3 →

d) (NH4)2SO4 + BaF2 →

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Combustion

A combustion reaction is one in which a substance rapidly combines with

____________________ to form one or more oxides. Combustion reactions involve a

compound composed of only C and H (and maybe O) that is reacted with oxygen gas. If the

combustion is complete, the products will be CO2 and __________________. Combustion

reactions produce heat, and are therefore considered exothermic reactions.

Complete and balance the following combustion reactions.

a) C4H10 + O2 →

b) C6H12O6 + O2 →

c) C8H8 + O2 →

d) C3H8O3 + O2 →

To determine which type a reaction is, look at the reactants. (E = element and C = compound)

E + E Synthesis

C Decomposition

E + C Single replacement

C + C Double replacement

CH cpd + O2 Combustion

Note: Two other common synthesis reactions include: nonmetallic oxide + water and metallic

oxide + water.

Identify whether the reaction is synthesis, decomposition, single replacement, double

replacement or combustion.

a) H2 + O2 →

b) H2O →

c) Mg(OH)2 + H2SO3 →

d) HgO →

e) KBr + Cl2 →

f) Zn + H2SO4 →

g) AgNO3 + NaCl →

h) C6H6 + O2 →

Homework / Practice

Directions: balance the following equations.

SYNTHESIS1. S + O2 ---> SO22. S + O2 ---> SO33. P + O2 ---> P2O3

4. Mg + N2 ---> Mg3N25. N2 + O2 --> NO26. Na + O2 ---> Na2O

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7. Cu + S ---> Cu2S8. Al + N2 ---> AlN

9. Hg + I2 ---> HgI210. Fe + O2 ---> Fe2O3

DECOMPOSITION11. HgO ---> Hg + O212. MgSO4.7H2O ---> MgSO4 + H2O13. KClO3 ---> KCl + O214. NH4NO3 ---> N2O + H2O15. NaNO3 ---> NaNO2 + O2

16. BaO2 ---> BaO + O217. H2O2 ---> H2O + O218. NO2 ---> N2 + O219. CaCO3 ---> CaO + CO220. H2O ---> H2 + O2

SINGLE REPLACEMENT (SINGLE DISPLACEMENT)21. AlI3 + Cl2 ---> AlCl3 + I222. CH4 + Cl2 ---> CHCl3 + HCl23. Al + CuSO4 ---> Al2(SO4)3 + Cu24. Fe2O3 + Al ---> Al2O3 + Fe25. Zn + HCl ---> ZnCl2 + H2

26. ZnS + O2 ---> ZnO + SO227. Na + H2O ---> NaOH + H228. Al + H2SO4 ---> Al2(SO4)3 + H229. Zn + NaOH ---> Na2ZnO2 + H230. AgNO3 + Zn ---> Zn(NO3)2 + Ag

DOUBLE REPLACEMENT 31. Fe(OH)3 + H2SO4 ---> Fe2(SO4)3 + H2O32. AgNO3 + K2CrO4 ---> Ag2CrO4 + KNO333. AgNO3 + CuCl2 ---> AgCl + Cu(NO3)234. Pb(NO3)2 + HCl ---> PbCl2 + HNO335. MgCl2 + NaOH ---> Mg(OH)2 + NaCl36. AgNO3 + H2S ---> Ag2S + HNO337. CaCO3 + HCl ---> CaCl2 + H2CO338. Hg2(NO3)2 + NaCl ---> Hg2Cl2 + NaNO339. BaCl2 + (NH4)2CO3 ---> BaCO3 + NH4Cl40. Al(OH)3 + NaOH ---> NaAlO2 + H2O

COMBUSTION41. CH4 + O2 ---> CO2 + H2O42. C4H10 + O2 ---> CO2 + H2O43. C3H6 + O2 ---> CO2 + H2O

44. C5H8 + O2 ---> CO2 + H2O45. CH3OH + O2 ---> CO2 + H2O46. C6H12O6 + O2 ---> CO2 + H2O

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Predict the products of the following reactions

47. MgCl2 + O2 ---> 48. Na + O2 ---> 49. P2O3 + H2O ---> 50. K2O + H2O ---> 51. BaO + CO2 ---> 52. BeO + CO2 ---> 53. Al2O3 + H2O ---> 54. N2O5 + H2O ---> 55. NaCl + O2 ---> 56. Ra + Cl2 ---> 57. Ni(ClO3)2 ---> 58. Ag2O ---> 59. HNO2 ---> 60. Fe(OH)3 ---> 61. ZnCO3 ---> 62. Cs2CO3 ---> 63. Al(OH)3 ---> 64. H2SO4 ---> 65. RbClO3 ---> 66. RaCl2 ---> 67. ZnS + O2 --->68. K + H2O --->

69. Fe + HCl --->70. NaI + Br2 --->71. Al + Pb(NO3)2 ---> 72. Cl2 + NaI ---> 73. Fe + AgC2H3O2 ---> 74. Al + CuCl2 ---> 75. Br2 + CaI2 ---> 76. Al + HCl ---> 77. Mg + HCl ---> 78. Zn + H2SO4 ---> 79. Fe + CuSO4 ---> 80. Cl2 + MgI2 ---> 81. Ca(OH)2 + H3PO4 ---> 82. K2CO3 + BaCl2 ---> 83. Cd3(PO4)2 + (NH4)2S ---> 84. Co(OH)3 + HNO3 ---> 85. AgNO3 + KCl ---> 86. Na2CO3 + H2SO4 ---> 87. Al(OH)3 + HC2H3O2 ---> 88. Al2(SO4)3 + Ca3(PO4)2 ---> 89. Cr2(SO3)3 + H2SO4 ---> 90. AgC2H3O2 + K2CrO4 --->

Write the complete ionic equation, identify the spectator ions, write the net ionic equation 91. K2CO3 + BaCl2 ---> BaCO3 + KCl92. Cd3(PO4)2 + (NH4)2S ---> CdS + (NH4)3PO4

93. AgNO3 + KCl ---> AgCl2 + K2NO3

94. Na2CO3 + H2SO4 ---> H2CO3 + Na2SO4 95. Al(OH)3 + HC2H3O2 ---> Al(C2H3O2)3 + HOH96. Al2(SO4)3 + Ca3(PO4)2 ---> AlPO4 + CaSO4

97. Cr2(SO3)3 + H2SO4 ---> Cr2(SO4)3 + H2SO3

98. AgC2H3O2 + K2CrO4 ---> Ag2CrO4 + KC2H3O2

Write the balanced equation (including states) and identify the type of reaction:99. Aqueous solutions of ammonium chloride and lead (II) nitrate produce lead (II) chloride

precipitate and aqueous ammonium nitrate.

100.Solid carbon disulfide burns in oxygen to yield carbon dioxide and sulfur dioxide gases.

101. Iron metal reacts with aqueous silver nitrate to produce aqueous iron (III) nitrate and silver metal.

102.Solid potassium nitrate yields solid potassium nitrite and oxygen gas.

103.Calcium metal reacts with chlorine gas to produce solid calcium chloride.

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Chemical Reactions and Balancing Practice Test

1. Write the balanced equation of the reaction that occurs when calcium carbonate decomposes to form calcium oxide and carbon dioxide.

Directions: Balance and identify the type of reaction2. ____K3PO4 + ____Al(NO3)3 ® ____KNO3 + ____AlPO4

3. ____Fe2O3 + ____Al ____Fe + ____Al2O3

4. ____NaOH ____Na2O + ____H2O5. ____HCl + ____Mg ____MgCl2 + ____H2

6. ____C2H4 + ____O2 ____CO2 + ____H2O

7. Write the balanced equation of the synthesis reaction that occurs when iron metal and oxygen gas react to form iron (III) oxide.

8. Write the balanced equation of the combustion reaction that occurs when ethane (C2H6) reacts with oxygen to form carbon dioxide and water.

9. Write the balanced equation of the reaction that occurs when calcium carbonate decomposes to form calcium oxide and carbon dioxide.

Directions: Predict the products and balance the reaction10. _____Na + ______O2 11. _____Al + _____Pb(NO3)2 12. _____NaF + _____Br2


13. In the following unbalanced reaction, what is the coefficient of HOH once the reaction is balanced? H2CO3 + KOH --> HOH + K2CO3

a. 1 b. 2 c. 3 d. 4

14. What are the different types of chemical reactions?a. synthesis, fusion, combustion, fission, and decompositionb. single replacement, combustion, and double replacementc. synthesis, fission, single replacement, combustion, and fusiond. synthesis, decomposition, combustion, single and double replacement

15. What type of reaction is represented by 2 or more elements forming a compound?a. Decompositionb. Synthesis

c. Combustiond. Single replacement

16. Decomposition is the burning of hydrocarbons in the presence of oxygen.a. True b. False

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17. Which equation represents a double replacement reaction?a. CaCO3 -> CaO + CO2

b. CH4 + 2O2 -> CO2 + 2H2Oc. LiOH + HCl -> LiCl + H2Od. C3H8 + 5O2 -> 3CO2 + 8H2O

18. MgSO4 + BaCl2 --> MgCl2 + BaSO4, is an example of what type of chemical reaction?

a. Single replacementb. Synthesis

c. Combustiond. Double replacement

19. Zn + 2 AgNO3 --> 2 Ag + Zn(NO3)2, is an example of what type of chemical reaction?

a. Synthesisb. Single replacement

c. Decompositiond. Double replacement

20. The cation of one compound replaces the cation in another compound in a double replacement reaction.

a. True b. False

21. Which statement best describes the conservation of atoms in all balanced chemical equations?a. There is a conservation of mass, number of protons, and charge.b. There is a conservation of mass, electronegativity, and charge.c. There is a conservation of only energy, and charge.d. There is a conservation of mass, energy, and charge.

22. Given the unbalanced equation ; CuS + O2 -> CuO + SO2 When it is balanced, what is the sum of the coefficients?a. 8 b. 9 c. 10 d. 11

23. Which one of these chemical reactions is balanced?a. Na + Cl2 -> NaClb. H2 + O2 -> H2O

c. CuCO3 -> CuO + CO2

d. KClO3-> KCl + O2

24. Which is the correct way of setting up a word equation for this balanced chemical equation, 2Na + Cl2 -> 2NaCl?a. Sodium react with chlorine gas to produce sodium chloride.b. 2 moles of sodium react with 1 mole of chlorine to yield 1 mole of sodium chloride.c. 2 moles of sodium react with 1 mole of chlorine gas to yield 2 mole of sodium

chloride.d. 2 moles of sodium added with 1 mole of chlorine gas to yield 1 mole of sodium

chloride.

25. 2 moles of copper react with 1 mole of oxygen gas to yield 2 moles of copper (ll) oxide. How would you express this word equation into a balanced chemical equation?a. Cu + O -> CuOb. Cu + O2 -> CuO

c. 2Cu + O -> CuOd. 2Cu + O2 -> 2CuO

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26. When the following reaction is balanced, the sum of all of the coefficients in the equation is:NaCl + H2SO4 + MnO2 → Na2SO4 + MnSO4 + H2O + Cl2

a. 11 b. 10

c. 6 d. 16

e. 14

27. When two ionic compounds are dissolved in water, a double replacement reaction can...

a. never occur since all ions in water are "spectator ions".b. occur if two of the ions form an insoluble ionic compound, which precipitates out

of solutionc. occur if the ions react to form a gas, which bubbles out of the solution.d. occur only if the ions form covalent bonds with each other.

28. Which equation represents combustion?a. 4 Fe + 3 O2 2 Fe2O3

b. 2H2O - 2H2 + O2

c. CH4 + 2O2 CO2 + 2 H2Od. Cu + 2 AgNO3 Cu(NO3)2 + 2 Ag

29. Given the unbalanced equation: Al + O2 Al2O3 When this equation is completely balanced using the smallest whole numbers, what is the sum of the coefficients?

a. 9 b. 7 c. 5 d. 4

30. Given the reaction CH4 + 2O2 --> CO2 + 2H2O,What amount of oxygen is needed to completely react with 1 mole of CH4?

a. 2 moles b. 2 atoms

c. 2 grams d. 2 molecules

31. The balanced equation for the complete combustion of benzene, C6H6, is

a. C6H6 + 12 H2O 6 CO2 + 15 H2

b. C6H6 6 C + 3 H2

c. 2 C6H6 + 9 O2 12 CO + 6 H2Od. C6H6 + O2 CO2 + H2Oe. 2 C6H6 + 15 O2 12 CO2 + 6 H2O

32. Which equation shows conservation of atoms?a. H2 + O2 ®H2Ob. H2 + O2 ®2H2O

c. 2H2 + O2 ®2H2Od. 2H2 + 2O2 ®2H2O

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33. The reaction of magnesium with elemental iodine, I2, yields magnesium iodide. Write a balanced chemical equation for this reaction. Which equation shows conservation of mass and charge?

a. NH4Br ®NH3 + Br2

b. 2Mg + Fe3+ ®Mg2+ + 3Fec. H2SO4 + LiOH ®Li2SO4 + H2Od. Cu + 2Ag®Cu2+ + 2Ag

34. When ethanol undergoes complete combustion, the products are carbon dioxide and water. __ C2H5OH + __ O2 __ CO2+ __ H2O What are the respective coefficients when the equation is balanced with the smallest whole numbers?

a. 2, 7, 4, 6b. 1, 3, 2, 3c. 2, 2, 1, 4

d. 1, 2, 3, 2e. 2, 4, 6, 4

35. What is the net ionic equation? AgNO3(aq) + KBr(aq) AgBr(s) + KNO3(aq)

a. K+(aq) + NO3-(aq) KNO3(s)

b. AgNO3(aq) + KBr(aq) AgBr(s)c. K+(aq) + NO3

-(aq) KNO3(aq)d. AgNO3(aq) + KBr(aq) AgBr(s) + KNO3(aq)e. Ag+(aq) + Br-(aq) AgBr(s)

36. Which equation shows conservation of atoms?a. H2 + O2 ®H2Ob. H2 + O2 ®2H2O

c. 2H2 + O2 ®2H2Od. 2H2 + 2O2 ®2H2O

STOICHIOMETRY

The word stoichiometry is Greek for “________________________ elements.” The calculations

of quantities in chemical reactions are based on a ______________________ equation. We can

interpret balanced chemical equations several ways. Using the methods of stoichiometry, we can

measure the amounts of substances involved in chemical reactions and relate them to one

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another. The group or unit of measure used to count numbers of atoms, molecules, or formula

units of substances is the ______________ (abbreviated mol).

Moles in Chemical Reactions

The coefficients tell us how many moles of each kind of element or compound we have.

2 Al2O3 → 4 Al + 3 O2

2 moles of aluminum oxide form 4 moles of aluminum and 3 moles of oxygen gas.

2 H2 + O2 → 2 H2O

___ mole(s) of hydrogen gas and ___ mole of oxygen form ___ mole(s) of water.

2 Na + 2 H2O → 2 NaOH + H2

___ moles of sodium and ___ moles of water form ___ moles of sodium hydroxide and ___ mole

of hydrogen gas.

2 Al2O3 → 4 Al + 3 O2

Every time we use 2 moles of Al2O3 we make 3 moles of O2. Every time we use 2 moles of

Al2O3 we make 4 moles of Al.

Using the balanced equation above, how many moles of O2 are produced when

3.34 moles of Al2O3 decompose?

2 C2H2 + 5 O2 → 4 CO2 + 2 H2O

a) If 3.84 moles of C2H2 are burned, how many moles of O2 are needed?

b) How many moles of C2H2 are needed to produce 8.95 moles of H2O?

c) If 2.47 moles of C2H2 are burned, how many moles of CO2 are formed?

SiCl4 + 2 Mg → 2 MgCl2 + Si

3.74 mol of Mg would make how many moles of Si?

Mass in Chemical Reactions

2 Al2O3 → 4 Al + 3 O2

2 x (102.0) grams of aluminum oxide form 4 x (27.0) grams of aluminum and 3 x (32.0) grams

of oxygen. The mass of Al2O3 was found by adding the masses of 2 aluminums & 3 oxygens.

(2 x 27.0 + 3 x 16.0 = 102.0)

2 H2 + O2 → 2 H2O

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2 x (_________) grams of hydrogen and ___ x (16.0) of oxygen form ___ x (_______) grams of

water.

2 Na + 2 H2O → 2 NaOH + H2

___ x (23.0) grams of sodium and 2 x (________) grams of water form ___ x (_________)

grams of sodium hydroxide and ___ x (________) grams of hydrogen gas.

The law of conservation of _____________ applies in chemical reactions. The mass of the

reactants equals the mass of the ________________________.

Show that the following equation follows the Law of Conservation of Mass.

2 Al2O3 → 4 Al + 3 O2

Mass – Mole Stoichiometry

The mass of 1 mole of a pure substance is called its _________________ mass. To convert the

mass of an element or compound to the number of moles, use the mass of 1 mol as a conversion

factor. We can convert ___________________ to moles using the periodic table. Then we must

apply the mole to mole conversion to change chemicals using the balanced equation. Finally we

will turn the moles back to grams using the periodic table.

2 C2H2 + 5 O2 → 4 CO2 + 2 H2O

a) How many moles of C2H2 are needed to produce 8.95 g of H2O?

b) If 2.47 moles of C2H2 are burned, how many grams of CO2 are formed?


How many moles of Mg are needed to make 9.3 g of Si?

3 Al + 3 NH4ClO4 → Al2O3 + AlCl3 + 3 NO + 6 H2O

How many moles of water are produced when 32 grams of aluminum are used?

CO2 + 2 LiOH → Li2CO3 + H2O

What mass of water can be produced from 3.66 moles of lithium hydroxide (LiOH)?

2 Al + 3 I2 → 2 AlI3

Calculate the mass of AlI3 (Aluminum Iodide) that can be produced from 3.00 mol of Al.

Mass – Mass Stoichiometry

2 Fe + 3 CuSO4 → Fe2(SO4)3 + 3 Cu

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If 10.1 g of Fe are added to a solution of copper (II) sulfate, how much solid copper

would form?

2 Al + 3 I2 → 2 AlI3

Calculate the mass of I2 needed just to react with 35.0 g of Al.


How many grams of MgCl2 are produced along with 9.3 g of silicon?

3 Al + 3 NH4ClO4 → Al2O3 + AlCl3 + 3 NO + 6 H2O

a) How many grams of Al must be used to react with 652 g of NH4ClO4?

b) How many grams of NO are produced if 150.0 grams of AlCl3 are also produced?

Particles in Chemical Reactions

The number of things in one mole is 6.022 x 1023. This big number has a short name: the

Avogadro constant.

Atom - ______________________

Molecule - Molecular compound (non-metals) or ______________________ (O2 etc.)

Formula unit - _________________ Compounds (Metal and non-metal or metal and a

polyatomic ion)

2 Al2O3 → 4 Al + 3 O2

2 x (6.022 x 1023) formula units of aluminum oxide form 4 x (6.022 x 1023) atoms of aluminum

and

3 x (6.022 x 1023) molecules of oxygen.

2 H2 + O2 → 2 H2O

2 x (___________) molecules of hydrogen and ___ x (6.022 x 1023) molecules of oxygen form

___ x (___________) molecules of water.

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Unit 7- Stoichiometry

2 Na + 2 H2O → 2 NaOH + H2

___ x (6.022 x 1023) atoms of sodium and ___ x (___________________) molecules of water

form ___ x (__________________) formula units of sodium hydroxide and ___ x (6.022 x 1023)

molecules of hydrogen gas.


How many moles of MgCl2 are produced along with 8.76 x 1024 atoms of silicon?

Gases and Reactions

In gas conversions, liters of a gas are converted to moles and vice-versa. ____________ stands

for standard temperature and pressure. 0ºC is standard _________________________, and

1 atmosphere is standard pressure. At STP, ____________ L of a gas = 1 mole

2 H2O → 2 H2 + O2

If 6.45 grams of water are decomposed, how many liters of oxygen will be produced at

STP?

CH4 + 2 O2 → CO2 + 2 H2O

How many liters of CH4 at STP are required to completely react with 17.5 L of O2?

2 C8H18 + 25 O2 → 16 CO2 + 18 H2O

Octane, C8H18, is one of the hydrocarbons in gasoline. How many liters of oxygen are

required, at STP, to burn 1.00 g of octane?

2 C4H10 + 13 O2 → 8 CO2 + 10 H2O

How many liters of CO2 at STP will be produced from the complete combustion of 23.2 g

C4H10?

2 NiS + 3 O2 → 2 NiO + 2 SO2

What volume of sulfur dioxide is produced from 123 grams of nickel (II) sulfide at STP?

According to Avogadro, equal volumes of gas, at the _____________ temperature and pressure,

contain the same number of particles. _______________ are numbers of particles. We can also

change between particles and liters at STP.

2 C4H10 + 13 O2 → 8 CO2 + 10 H2O

a) How many molecules of CO2 at STP will be produced from the complete combustion

of 18.2 L C4H10 ?

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b) How many molecules of O2 at STP are needed to produce 18.2 L of steam?

c) How many liters of CO2 at STP are produced from 3.2 x 1024 molecules of butane,

C4H10?

4 NH3 + 6 NO → 5 N2 + 6 H2O

Nitrogen monoxide is a pollutant found in smokestack emissions. How many liters of

ammonia, NH3, at STP are needed to produce 1.4 x 1023 molecules of H2O?

Homework / Practice

Solve the following problems. The reactions may not be balanced.

1. If 20.0 g of magnesium react with excess hydrochloric acid, how many grams of magnesium chloride are produced? Mg + HCl ---> MgCl2 + H2

2. How many grams of chlorine gas must be reacted with excess sodium iodide if 10.0 g of sodium chloride are needed? NaI + Cl2 ---> NaCl + I2

3. How many moles of oxygen gas are produced in the decomposition of 5.00 g of potassium chlorate? KClO3 ---> KCl + O2

4. What mass of copper is required to replace silver from 4.00 g of silver nitrate dissolved in water? Cu + AgNO3 ---> Cu(NO3)2 + Ag

5. If excess ammonium sulfate reacts with 20.0 g of calcium hydroxide, how many grams of ammonia (NH3) are produced? (NH4)2SO4 + Ca(OH)2 ---> CaSO4 + NH3 + H2O

6. If excess sulfuric acid reacts with 0.2564 moles of sodium chloride, how many grams of hydrochloric acid are produced? H2SO4 + NaCl ---> HCl + Na2SO4

7. How many grams of silver phosphate are produced if 10.0 g of silver acetate react with excess sodium phosphate? AgC2H3O2 + Na3PO4 ---> Ag3PO4 + NaC2H3O2

8. How many moles of sodium hydroxide are needed to completely neutralize 25.0 g of sulfuric acid? NaOH + H2SO4 ---> Na2SO4 + H2O

9. When calcium carbonate is heated strongly, carbon dioxide gas is released. CaCO3 ---> CaO + CO2 What volume of carbon dioxide, measured at STP, is produced if 15.2 g of calcium carbonate is heated?

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10. What volume of oxygen gas at STP is needed for complete combustion of 5.63 g of propane? C3H8 + O2 ---> CO2 + H2O

11. What volume of chlorine gas, measured at STP, is needed to produce 10.0 g of potassium permanganate (KMnO4)? K2MnO4 + Cl2 ---> KMnO4 + KCl

12. Suppose that you could decompose 0.250 mol of Ag2S into its elements. a. How many moles of silver would form? b. How many moles of sulfur would form from 38.8 g of silver sulfide?

13. Ammonia (NH3) is made industrially by reacting nitrogen gas and hydrogen gas under pressure, at high temperature and in the presence of a catalyst. If 4.0 mol of hydrogen react, how many moles of ammonia will be produced?

14. How many grams of sodium hydroxide can be produced from 500. g of calcium hydroxide according to the equation: Ca(OH)2 + Na2CO3 ---> 2 NaOH + CaCO3?

15. How many liters of Cl2 can be produced from 5.60 mole HCl at STP? 4 HCl + O2 ---> 2 Cl2 + 2 H2O

16. Given the equation Al4C3 + 12 H2O ---> 4 Al(OH)3 + 3 CH4 How many moles of water are needed to react with 100. g Al4C3?

17. How many grams of zinc phosphate are formed when 10.0 g of Zn are reacted with the phosphoric acid? The other product is hydrogen gas.

18. Given the equation 4 FeS2 + 11 O2 ---> 2 Fe2O3 + 8 SO2 How many liters of O2 are required to react with 4.50 mol of FeS2 at STP?

19. Given the equation C2H4 + 3 O2 ---> 2 CO2 + 2 H2Oa. If 6.0 mol of CO2 are produced, how many moles of O2 were reacted?b. How many liters of O2 are required for the complete reaction of 45 g of C2H4 at

STP?c. If 18.0 g of CO2 are produced, how many grams of H2O are produced?

20. According to his pre-laboratory theoretical yield calculations, a student’s experiment should have produced 1.44 g of magnesium oxide. When he weighed his product after reaction, only 1.23 g of magnesium oxide was present. What was the student’s percent yield?

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Balance the following equations to use with questions 25 – 32:

21. ____ Al + ____ O2 ® ____ Al2O3

22. ____ Cu + ____ AgNO3 ® ____ Ag + ____ Cu(NO3)2

23. ____ Zn + ____ HCl ® ____ ZnCl2 + ____ H2

24. ____ Fe + ____ Cl2 ® ____ FeCl3

Perform the following calculations:

25. Zinc reacts with hydrochloric acid to produce zinc chloride and hydrogen. How many moles of HCl are required to produce 7.50 moles of ZnCl2?

26. Copper metal reacts with silver nitrate to form silver and copper (II) nitrate. How many grams of copper are required to form 250 g of silver?

27. When aluminum is burned in excess oxygen, aluminum oxide is produced. How many grams of oxygen are required to produce 0.75 moles of Al2O3?

28. How many grams of iron (III) chloride are produced when 15.3 g of iron react with excess chlorine gas?

29. Copper metal reacts with silver nitrate to form silver and copper (II) nitrate. How many moles of silver will be produced from 3.65 moles of silver nitrate?

30. When 9.34 g of zinc react with excess hydrochloric acid how many grams of zinc chloride will be produced?

31. How many grams of iron are needed to react with 31.0 L of chlorine gas at STP to produce iron (III) chloride?

32. How many liters of oxygen gas at STP are required to react with 65.3 g of aluminum in the production of aluminum oxide?

33. How many liters of ammonia gas are formed when 25 L of hydrogen at STP?

____ N2 + ____ H2 ® ____ NH3

34. Given the following equation: Na2O + H2O ---> 2 NaOH How many grams of Na2O are required to produce 1.60 x 102 grams of NaOH?

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35. Given the following equation: 8 Fe + S8 ---> 8 FeS

a. What mass of iron is needed to react with 16.0 grams of sulfur? b. How many grams of FeS are produced?

36. Given the following equation: 2 NaClO3 ---> 2 NaCl + 3 O2 a. 12.00 moles of NaClO3 will produce how many grams of O2? b. How many grams of NaCl are produced when 80.0 grams of O2 are produced?

37. Given the following equation: Cu + 2 AgNO3 ---> Cu(NO3)2 + 2 Aga. How many moles of Cu are needed to react with 3.50 moles of AgNO3? b. If 89.5 grams of Ag were produced, how many grams of Cu reacted?

38. Molten iron and carbon monoxide are produced in a blast furnace by the reaction of iron (III) oxide and coke (pure carbon). If 25.0 kilograms of pure Fe2O3 is used, how many kilograms of iron can be produced? The reaction is: Fe2O3 + 3 C ---> 2 Fe + 3 CO

39. The average human requires 120.0 grams of glucose (C6H12O6) per day. How many grams of CO2 (in the photosynthesis reaction) are required for this amount of glucose? The photosynthetic reaction is: 6 CO2 + 6 H2O ---> C6H12O6 + 6 O2

40. Given the reaction: 4 NH3 (g) + 5 O2 (g) ---> 4 NO (g) + 6 H2O (l) When 1.20 mole of ammonia reacts, the total number of moles of products formed is:

Stoichiometry Practice Test

Directions: Solve the following problems, showing all work.

1. Balance the equation ______NaOH ______Na2O + _____H2O

2. How many moles of water are produced from 4 moles of sodium hydroxide?

3. Balance the equation ____KCl + _____O2 _____KClO3

4. How many moles of potassium chlorate are produced from 9 moles of oxygen?

5. Fe2O3 + 2Al 2Fe + Al2O3

What mass of aluminum oxide is produced when 4 moles of aluminum react?

6. P4O10 + 6H2O 4H3PO4

How many grams of phosphoric acid are produced by the reaction of 12.5g of water?

7. Using the reaction in question 6, how many grams of P4H10 must react if the reaction produces 25 moles H3PO4?

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8. Balance the equation _____HNO3 + ______Cu _______Cu(NO3)2 + ______H2

9. How many moles of nitric acid must react in order to form 83g of copper nitrate?

10. Balance the equation ______NH3 + ________O2 _______NO + ______H2O

11. What mass of nitrogen monoxide will be formed when 7.2g nitrogen trihydride react?

12. C2H4 + 3O2 2CO2 + 2H2O Determine the mass of water produced if 50g C2H4 and 50g O2 react.


13. Consider the balanced equation Zn + 2HCl -> ZnCl2 + H2 How many moles of ZnCl2 will be produced if 7 moles of HCl are used?

a. 2 molesb. 2.5 moles

c. 3.5 molesd. 4 moles

14. Given : C2H2(g) + 5O2(g) -> 4CO2(g) + 2H2O(g) Is this chemical equation balanced?a. True b. False

15. In the reaction below, how many moles of oxygen gas is produced by the decomposition of 4moles of mercury (II) oxide? 2HgO -> 2Hg + O2

a. 1 moleb. 2 moles

c. 3 molesd. 4 moles

16. True or False, 6 moles of H2 is needed to completely react with 2 moles of N2 in the balanced chemical reaction N2 + 3H2 -> 2NH3

a. True b. False

17. If 18.0 grams of carbon are burned in 55.0 grams of oxygen, how many grams of carbon dioxide are formed?

a. 44.01 grams CO2 b. 75.6 grams CO2

c. 151 grams CO2 d. 66.0 grams CO2

18. A mass of 21.5 grams of calcium hydroxide reacts with an excess of phosphoric acid. What mass of calcium phosphate could be recovered from solution?

a. 284 grams b. 186 grams

118



e. 326 grams

19. If 3.64 g of calcium hydroxide react with excess sodium sulfate in aqueous solution to produce solid sulfate and aqueous sodium hydroxide, how many moles of calcium atoms are reacting here? Ca(OH)2(aq) + Na2SO4(aq) CaSO4(s) + 2NaOH(aq)

a. 0.00982 molb. 0.0246 molc. 0.0266 mol

d. 0.0491 mole. 0.0909 mol

20. If one mole of the rocket fuel ammonium perchlorate, NH4ClO4 (s) is allowed to react with excess Al so all of the NH4ClO4 is consumed, how many molecules of water will be produced?3NH4ClO4 (s) + 3Al (s) Al2O3 (s) + AlCl3 (s) + 3NO (g) + 6H2O (g)

a. 3.61 x 1023

b. 1.0 x 1023

c. 6.02 x 1023

d. 1.20 x 1024

e. 3.01 x 1024

21. How many grams of potassium cyanide, PCl3, is produced from 93.0 grams of P4 (s) and 213 g of Cl2 (g), assuming the reaction goes to completion? The balanced equation for the reaction is: P4 (s) + 6Cl2 (g) 4PCl3 (g)

a. 277 gb. 416 gc. 213 g

d. 104 ge. 69.3 g

22. How many moles of Al2O3 are formed when a mixture of 0.36 moles Al and 0.36 moles O2 is ignited?

a. 0.12b. 0.18

c. 0.28d. 0.46

e. 0.72

23. In the oxidation of ethane: 2 C2H6 + 7 O2 → 4 CO2 + 6 H2O how many moles of O2 are required to react with 1 mole of ethane?

a. 7 moles b. 2 moles c. 3.5 moles

24. In the reaction: 2 C2H6 + 7 O2 → 4 CO2 + 6 H2O how many moles of CO2 are formed when 1mole of O2 is consumed?

a. 7 moles b. 1.75 moles c. 0.57 moles

119


25. In the reaction: 2 C2H6 + 7 O2 → 4 CO2 + 6 H2O how many moles of CO2 are formed when 5moles of ethane are consumed?

a. 10 moles b. 4 moles c. 2 moles

26. How many mL of 0.1 M HCl are required to react with 0.01 mole of Na2CO3? HCl + Na2CO3 NaCl + H2CO3

a. 100 mL b. 200 mL c. 50 mL

27. How many liters of H2 at STP are required to react with 2.3 g of Fe3O4? H2

+ Fe3O4 FeO + H2O

a. 0.22 L b. 0.44 L c. 0.56 L

28. When 0.05 mole H2 is mixed with 0.05 mole CO, what is the maximum number of moles of methanol (CH3OH) that can be obtained? H2 + CO CH3OH

a. 0.10 mole b. 0.05 mole c. 0.025 mole

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Unit 8- Gas Laws

THE GAS LAWS

The gas laws describe how gases behave. They can be predicted by theory and the amount of

change can be calculated with mathematical equations. One ____________________________

is equal to 760 mm Hg, 760 torr, or _______________ kPa (kilopascals).

Perform the following pressure conversions.

a) 144 kPa = ______________ atm b) 795 mm Hg = ______________ atm

c) 669 torr = ______________ kPa d) 1.05 atm = ______________ mm Hg

Air pressure at higher altitudes, such as on a mountaintop, is slightly ______________________

than air pressure at sea level. Air pressure is measured using a ________________________.

More molecules mean more ____________________ between the gas molecules themselves and

more collisions between the gas molecules and the walls of the container. Number of molecules

is ________________________ proportional to pressure. Doubling the number of gas particles

in a basketball _____________________ the pressure. Gases naturally move from areas of high

pressure to ____________ pressure because there is empty space to move in. If you double the

number of molecules, you _____________________ the pressure. As you remove molecules

from a container, the pressure ________________________ until the pressure inside equals the

pressure outside. In a smaller container, molecules have less room to move. The molecules hit

the sides of the container _________________ often, striking a smaller area with the same force.

As volume decreases, pressure increases. Volume and pressure are ______________________

proportional. As the pressure on a gas increases, the volume decreases. Raising the temperature

of a gas increases the _______________________ if the volume is held constant. At higher

temperatures, the particles in a gas have greater ________________________ energy. They

move faster and collide with the walls of the container more often and with greater

___________________, so the pressure rises. If you start with 1 liter of gas at 1 atm pressure

and 300 K and heat it to 600 K, one of 2 things happens. Either the volume will increase to

2 liters at ______ atm, or the pressure will increase to ______ atm while the volume remains

constant.

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Unit 8- Gas Laws

Ideal Gases and the Kinetic Molecular Theory

In this unit we will assume the gases behave ideally. _____________________ gases do not

really exist, but this makes the math easier and is a close approximation. Gas particles are much

smaller than the spaces between them. The particles have negligible _____________________.

There are no attractive or repulsive ___________________ between gas molecules. Gas

particles are in constant, _________________________ motion. Until they bump into something

(another particle or the side of a container), particles move in a straight line. No kinetic energy is

____________________ when gas particles collide with each other or with the walls of their

container. All gases have the same ______________________ energy at a given temperature.

Temperature is a measure of the average kinetic energy of the particles in a sample of matter.

There are no gases for which this is true. Real gases behave more ideally at ________________

temperature and _________________ pressure. At low temperature, the gas molecules move

more _______________________, so attractive forces are no longer negligible. As the pressure

on a gas increases, the molecules are forced closer together and _________________________

forces are no longer negligible. Therefore, real gases behave more ideally at high temperature

and low pressure.

Avogadro’s Law

Avogadro’s law states that equal volumes of different gases (at the same temperature and

pressure) contain equal numbers of ________________ or molecules. 2 liters of helium has the

same number of particles as ______ liters of oxygen. The molar volume for a gas is the volume

that one mole occupies at 0.00ºC and 1.00 atm. 1 mole = 22.4 L at STP (standard temperature

and pressure). As a result, the volume of gaseous reactants and products can be expressed as

small whole numbers in reactions.

How many moles are in 45.0 L of a gas at STP?

How many liters are in 0.636 moles of a gas at STP?

The volume of a gas is directly proportional to the number of moles.

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Unit 8- Gas Laws

Consider two samples of nitrogen gas. Sample 1 contains 1.5 mol and has a volume of

36.7 L. Sample 2 has a volume of 16.5 L at the same temperature and pressure.

Calculate the number of moles of nitrogen in sample 2.

If 0.214 mol of argon gas occupies a volume of 652 mL at a particular temperature and

pressure, what volume would 0.375 mol of argon occupy under the same conditions?

If 46.2 g of oxygen gas occupies a volume of 100. L at a particular temperature and

pressure, what volume would 5.00 g of oxygen gas occupy under the same conditions?

Boyle’s Law

At Boyle’s law states that the pressure and volume of a gas at constant temperature are inversely

proportional. Inversely proportional means as one goes up the other goes ________________.

P1 V1 = P2 V2

Sketch the PV graph that represents Boyle’s law.

The P-V graph for Boyle’s law results in a _____________________________ because

pressure and volume are inversely proportional.

A balloon is filled with 25 L of air at 1.0 atm pressure. If the pressure is changed to 1.5

atm, what is the new volume? (Make sure the pressure and volume units in the question

match.)

A balloon is filled with 73 L of air at 1.3 atm pressure. What pressure is needed to

change the volume to 43 L?

A gas is collected in a 242 cm3 container. The pressure of the gas in the container is

measured and determined to be 87.6 kPa. What is the volume of this gas at standard

pressure?

A gas is collected in a 24.2 L container. The pressure of the gas in the container is

determined to be 756 mm Hg. What is the pressure of this gas if the volume increases to

30.0 L?

Charles’ Law

The volume of a gas is directly proportional to the Kelvin temperature if the pressure is held

constant.

V1 V2

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Unit 8- Gas Laws

= T1 T2 K = °C + 273

Sketch the PV graph that represents Charles’ law.

The V-T graph for Charles’ law results in a _____________________________

_________________ because pressure and volume are directly proportional.

What is the temperature of a gas that is expanded from 2.5 L at 25 ºC to 4.1 L at constant

pressure? (Make sure the volume units in the question match and make sure to convert

degrees Celsius to Kelvin.)

What is the final volume of a gas that starts at 8.3 L and 17 ºC and is heated to 96 ºC?

A 225 cm3 volume of gas is collected at 57 ºC. What volume would this sample of gas

occupy at standard temperature?

A 225 cm3 volume of gas is collected at 42 ºC. If the volume is decreased to 115 cm3,

what is the new temperature?

Gay-Lussac’s Law

The temperature and the pressure of a gas are directly related at constant volume.

P1 P2

= T1 T2

Sketch the PT graph that represents Gay-Lussac’s law.

What is the pressure inside a 0.250 L can of deodorant that starts at 25 ºC and 1.2 atm if

the temperature is raised to 100 ºC? Volume remains constant. (Make sure the pressure

units in the question match and make sure to convert degrees Celsius to Kelvin.)

A can of deodorant starts at 43 ºC and 1.2 atm. If the volume remains constant, at what

temperature will the can have a pressure of 2.2 atm?

A can of shaving cream starts at 25 ºC and 1.30 atm. If the temperature increases to 37

ºC and the volume stays constant, what is the pressure of the can?

A 12 ounce can of a soft drink starts at STP. If the volume remains constant, at what

temperature will the can have a pressure of 2.20 atm?

The Combined Gas Law

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Unit 8- Gas Laws

The gas laws may be combined into a single law, called the combined gas law, which relates two

sets of conditions of pressure, volume, and temperature by the following equation.

P1 V1 P2 V2

= T1 T2

A 15 L cylinder of gas at 4.8 atm pressure at 25 ºC is heated to 75 ºC and compressed to

17 atm. What is the new volume?

If 6.2 L of gas at 723 mm Hg at 21 ºC is compressed to 2.2 L at 4117 mm Hg, what is the

temperature of the gas?

A sample of nitrogen monoxide has a volume of 72.6 mL at a temperature of 16 °C and a

pressure of 104.1 kPa. What volume will the sample occupy at 24 °C and 99.3 kPa?

A hot air balloon rises to an altitude of 7000 m. At that height the atmospheric pressure

drops to 300. mm Hg and the temperature cools to -33 °C. Suppose on the hot air balloon

there was a small balloon filled to 1.00 L at sea level and a temperature of 27 °C. What

would its volume ultimately be when it reached the height of 7000 m?

Dalton’s Law of Partial Pressures

Dalton’s law of partial pressures states that the _________________ pressure of a mixture of

gases is equal to the sum of the pressures of all the gases in the mixture, as shown below.

Pt = P1 + P2 + P3 + … Pt = total pressureThe partial pressure is the contribution by that gas.

What is the total pressure in a balloon filled with air if the pressure of the oxygen is

170 mm Hg and the pressure of nitrogen is 620 mm Hg?

In a second balloon the total pressure is 1.30 atm. What is the pressure of oxygen (in mm

Hg) if the pressure of nitrogen is 720. mm Hg?

A container has a total pressure of 846 torr and contains carbon dioxide gas and nitrogen

gas. What is the pressure of carbon dioxide (in kPa) if the pressure of nitrogen is 50. kPa?

When a container is filled with 3 moles of H2, 2 moles of O2 and 4 moles of N2, the

pressure in the container is 8.7 atm. The partial pressure of H2 is _____.

It is common to synthesize gases and collect them by displacing a volume of

________________.

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Unit 8- Gas Laws

Hydrogen was collected over water at 21°C on a day when the atmospheric pressure is

748 torr. The volume of the gas sample collected was 300. mL. The vapor pressure of

water at 21°C is 18.65 torr. Determine the partial pressure of the dry gas.

A sample of oxygen gas is saturated with water vapor at 27ºC. The total pressure of the

mixture is 772 mm Hg and the vapor pressure of water is 26.7 mm Hg at 27ºC. What is

the partial pressure of the oxygen gas?

The Ideal Gas Law

Remember ideal gases do not exist. Molecules do take up ______________________. There

are _________________________ forces; otherwise, there would be no liquids.

P V = n R TPressure times volume equals the number of ___________________ (n) times the ideal gas

constant (R) times the temperature in Kelvin.

R = 0.0821 (L atm)/(mol K) or R = 8.314 (L kPa)/(mol K) or R = 62.4 (L mm

Hg)/(mol K)

The one you choose depends on the unit for pressure!

How many moles of air are there in a 2.0 L bottle at 19 ºC and 747 mm Hg?

What is the pressure in atm exerted by 1.8 g of H2 gas exerted in a 4.3 L balloon at 27 ºC?

Sulfur hexafluoride (SF6) is a colorless, odorless and very unreactive gas. Calculate the

pressure (in atm) exerted by 1.82 moles of the gas in a steel vessel of volume 5.43 L at

69.5 ºC.

Calculate the volume (in liters) occupied by 7.40 g of CO2 at STP.

A sample of nitrogen gas kept in a container of volume 2.30 L and at a temperature of

32 ºC exerts a pressure of 476 kPa. Calculate the number of moles of gas present.

A 1.30 L sample of a gas has a mass of 1.82 g at STP. What is the molar mass of the

gas?

Calculate the mass of nitrogen gas that can occupy 1.00 L at STP.

Homework / Practice

1. Identify whether the descriptions below describe an ideal gas or a real gas.a) Gas particles move in straight lines until they collide with other particles or the

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Unit 8- Gas Laws

walls of their container.b) Individual gas particles have a measurable volume.c) The gas will not condense even when compressed or cooled.d) Collisions between molecules are perfectly elastic.e) Gas particles passing close to one another exert an attraction on each other.

2. The formula for kinetic energy is KE = 1/2mv2.a) What happens to KE if the mass is tripled (at constant speed)?b) What happens to KE if the speed is halved (at constant mass)?c) If two gases at the same temperature share the same KE, it follows that the

molecules of greater mass have the _____ speed. (faster or slower)

3. Explain the following using the kinetic-molecular theory: a) As a gas is heated, its rate of effusion through a small hole increases if all other

factors remain constant.b) A strong-smelling gas released from a container in the middle of a room is soon

detected in all areas of the room.

4. Pressure = force / area. For a constant force, when the surface area is quadrupled, the pressure

5. Rank the following in increasing order.a) 50 kPa b) 2 atm c) 76 torr

6. Does atmospheric pressure increase or decrease as altitude above sea level increases?

7. Convert the following:a. 0.200 atm = _____ mm Hgb. 790 mm Hg = _____ Pa

c. 123 kPa = _____ atmd. 0.935 atm = ______ torr

8. The mercury level in an open manometer is 25 mm Hg higher in the arm connected to the atmosphere. If atmospheric pressure is 765 mm Hg, calculate the pressure of the enclosed gas.

9. The mercury level in an open manometer is 32 mm Hg lower in the arm connected to the atmosphere. If atmospheric pressure is 765 mm Hg, calculate the pressure of the enclosed gas.

10. A 24 L sample of a gas (at fixed mass and constant temperature) exerts a pressure of 3.0 atm. What pressure will the gas exert if the volume is changed to 16 L?

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Unit 8- Gas Laws

11. An air bubble with a volume of 2.0 mL forms at the bottom of a lake, where the pressure is 3.0atm. As it rises, the pressure on the bubble decreases. Assume the temperature remains constant.

a. Will the bubble expand or contract as it rises?b. Predict the volume of the bubble just as it reaches the surface, where the pressure

is 1.0atm.

12. A common laboratory system to study Boyle’s law uses a gas trapped in a syringe. The pressure in the system is changed by adding or removing identical weights on the plunger. The original gas volume is 50.0 mL when two weights are present. Predict the new gas volume when 4 more weights are added.

13. Helium gas in a balloon occupies 2.40 L at 400. K. What volume will it occupy at 300 K?

14. A bicycle tire is inflated to 55 lb/in2 at 15 °C. Assume that the volume of the tires does not change appreciably once it is inflated.

a. The tire and the air inside it are heated to 30 °C by road wear, does the pressure in the tire increase or decrease?

b. Because the temperature has doubled, does the pressure double to 110 psi? Why or why not?

15. If 0.864 mol of neon gas occupies a volume of 452 mL at a particular temperature and pressure, what volume would 0.575 mol of neon occupy under the same conditions?

16. If 26.5 g of oxygen gas occupies a volume of 100. L at a particular temperature and pressure, how many moles of oxygen gas will there be in 350. L under the same conditions?

17. At one point in the cycle of a piston in an automobile engine, the volume of the trapped fuel mixture is 400 cm3 at a pressure of 1.0 atm and a temperature of 27 °C. In the compression of the piston, the temperature reaches 77 °C and the volume decreases to 50.0 cm3. What is the new pressure?

18. On a cold winter morning when the temperature is - 13 °C, the air pressure in an automobile tire is 1.5 atm. If the volume does not change, what will the pressure be after the tire has warmed to 13 °C?

19. A gas storage tank has a volume of 3.5 x1 5 m3 when the temperature is 27 °C and the pressure is 1.0 atm. What is the new volume of the tank if the temperature drops to - 10.°C and the pressure drops to 0.95 atm?

20. Explain how to correct for the partial pressure of water vapor when calculating the partial pressure of a dry gas that is collected over water.

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Unit 8- Gas Laws

21. A sample of chlorine gas is collected by water displacement at 23 °C. If the atmospheric pressure is 751 torr, what is the partial pressure due to the chlorine? The vapor pressure of water at 23 °C is 21.1 mm Hg.

22. When an explosive like TNT is detonated, a mixture of gases at high temperature is created. Suppose that gas X has a pressure of 50 atm, gas Y has a pressure of 20 atm, and gas Z has a pressure of 10 atm.

a. What is the total pressure of the system?b. Once the gas mixture combines with air, Ptotal soon drops to 2 atm. By what

factor does the volume of the mixture increases? (Assume mass and temperature are constant.)

23. A gas occupies a volume of 180 mL at 35.0 °C and 740 mm Hg. What is the volume of the gas at STP?

24. Perform the following calculationsa. How many moles of methane, CH4, are present in 5.6 L of the gas at STP?b. How many moles of gas are present in 5.6 L of any ideal gas at STP?c. What is the mass of the 5.6 L sample of methane gas?

25. What is the pressure exerted by 32 g of oxygen gas in a 20. L container at 30.0 °C?

26. How many grams of nitrogen gas are in a flask with a volume of 250 mL at a pressure of 3.0 atm and a temperature of 300. K?

27. A container holds three gases: oxygen, carbon dioxide, and helium. The partial pressures of the three gases are 2.00 atm, 3.00 atm, and 4.00 atm, respectively. What is the total pressure inside the container?

28. A gas occupies 12.3 liters at a pressure of 40.0 mm Hg. What is the volume when the pressure is increased to 60.0 mm Hg?

29. If a gas at 25.0 °C occupies 3.60 liters at a pressure of 1.00 atm, what will be its volume at a pressure of 2.50 atm?

30. A gas occupies 1.56 L at 1.00 atm. What will be the volume of this gas if the pressure becomes 3.00 atm?

31. A gas occupies 11.2 liters at 0.860 atm. What is the pressure if the volume becomes 15.0 L?

32. How much will the volume of 75.0 mL of neon change if the pressure is lowered from 50.0 torr to 8.00 torr?

33. Calculate the decrease in temperature when 2.00 L at 20.0 °C is compressed to 1.00 L.

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Unit 8- Gas Laws

34. 600.0 mL of air is at 20.0 °C. What is the volume at 60.0 °C?

35. A gas occupies 900.0 mL at a temperature of 27.0 °C. What is the volume at 132.0 °C?

36. What change in volume results if 60.0 mL of gas is cooled from 33.0 °C to 5.00 °C?

37. A gas occupies 1.00 L at standard temperature. What is the volume at 333.0 °C?

38. Determine the pressure change when a constant volume of gas at 1.00 atm is heated from 20.0°C to 30.0 °C.

39. A gas has a pressure of 0.370 atm at 50.0 °C. What is the pressure at standard temperature?

40. A gas has a pressure of 699.0 mm Hg at 40.0 °C. What is the temperature at standard pressure?

41. If a gas is cooled from 323.0 K to 273.15 K and the volume is kept constant what final pressure would result if the original pressure was 750.0 mm Hg?

42. If a gas in a closed container is pressurized from 15.0 atmospheres to 16.0 atmospheres and its original temperature was 25.0 °C, what would the final temperature of the gas be?

43. A gas has a volume of 800.0 mL at negative 23.00 °C and 300.0 torr. What would the volume of the gas be at 227.0 °C and 600.0 torr of pressure?

44. 500.0 liters of a gas are prepared at 700.0 mm Hg and 200.0 °C. The gas is placed into a tank under high pressure. When the tank cools to 20.0 °C, the pressure of the gas is 30.0 atm. What is the volume of the gas?

45. What is the volume of gas at 2.00 atm and 200.0 K if its original volume was 300.0 L at 0.250 atm and 400.0 K.

46. At conditions of 785.0 torr of pressure and 15.0 °C temperature, a gas occupies a volume of 45.5 mL. What will be the volume of the same gas at 745.0 torr and 30.0 °C?

47. A gas occupies a volume of 34.2 mL at a temperature of 15.0 °C and a pressure of 800.0 torr. What will be the volume of this gas at standard conditions?

48. The volume of a gas originally at standard temperature and pressure was recorded as 488.8 mL. What volume would the same gas occupy when subjected to a pressure of 100.0 atm and temperature of minus 245.0 °C?

49. At a pressure of 780.0 mm Hg and 24.2 °C, a certain gas has a volume of 350.0 mL. What will be the volume of this gas under STP

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Unit 8- Gas Laws

50. A gas sample occupies 3.25 liters at 24.5 °C and 1825 mm Hg. Determine the temperature at which the gas will occupy 4250 mL at 1.50 atm.

51. If 10.0 liters of oxygen at STP are heated to 512 °C, what will be the new volume of gas if the pressure is also increased to 1520.0 mm of mercury?

52. If 2.00 liters of hydrogen, originally at 25.0 °C and 750.0 mm of mercury, are heated until a volume of 20.0 liters and a pressure of 3.50 atmospheres is reached. What is the new temperature?

53. How many moles of gas are contained in 890.0 mL at 21.0 °C and 750.0 mm Hg pressure?

54. Calculate the volume 3.00 moles of a gas will occupy at 24.0 °C and 762.4 mm Hg.

55. What volume will 20.0 g of Argon occupy at STP?

56. How many moles of gas would be present in a gas trapped within a 100.0 mL vessel at 25.0 °C at a pressure of 2.50 atmospheres?

57. How many moles of a gas would be present in a gas trapped within a 37.0 liter vessel at 80.00°C at a pressure of 2.50 atm?

58. At what pressure would 0.150 mole of nitrogen gas at 23.0 °C occupy 8.90 L?

59. What volume would 32.0 g of NO2 gas occupy at 3.12 atm and 18.0 °C?

60. Find the volume of 2.40 mol of gas whose temperature is 50.0 °C and whose pressure is 2.00atm.

61. How many moles of gas are contained in a 50.0 L cylinder at a pressure of 100.0 atm and a temperature of 35.0 °C?

62. Determine the number of moles of Krypton contained in a 3.25 liter gas tank at 5.80 atm and 25.5 °C. If the gas is Oxygen instead of Krypton, will the answer be the same? Why or why not?

63. A 500.0 mL sample of a gas is collected at 745.0 mm Hg. What will the volume be at standard pressure?

64. Convert 350.0 mL at 740.0 mm of Hg to its new volume at standard pressure.

65. The temperature of a sample of gas in a steel container at 30.0 kPa is increased from -100.0 °C to 1.00 x 103 °C. What is the final pressure inside the tank?

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Unit 8- Gas Laws

Gas Laws Practice Test

1. Explain how the temperature is related to the kinetic energy and motion of gas particles.

2. If the volume of a gas contained within balloon were to be tripled, what would be the impact upon the pressure if Kelvin temperature is maintained as constant?

Directions: Solve the following problems. Show all your work, including units 3. In a mixture of carbon dioxide, oxygen gas, sulfur dioxide and carbon monoxide, the

pressure of the carbon dioxide is 0.3 atm, oxygen gas is 0.5 atm, sulfur dioxide is 0.6 atm, and the pressure of the carbon monoxide is 0.1 atm. What is the total pressure in the container?

4. A high-altitude balloon contains 4 Liters of helium gas at 1.35atm. What is the volume when the balloon rises to an altitude where the pressure is only 1.20atm? (Assume that the temperature remains constant.)

5. If a sample of gas occupies 27 Liters at 12 Celsius, what will be its volume at 112 Celsius if the pressure does not change?

6. A gas has a pressure of 122kPa at -6 Celsius (negative 6). What will be the pressure at 85 Celsius if the volume does not change?

7. A gas at 10 kPa and 45 Celsius occupies a container with an initial volume of 4 Liters. By changing the volume, the pressure of the gas increases to 25 kPa as the temperature is raised to 190 Celsius. What is the new volume?

8. You fill a rigid steel cylinder that has a volume of 840 milliliters with oxygen gas to a final pressure of 1.1 atmospheres at 145 Celsius. How many moles of nitrogen gas does the cylinder contain?

9. What is the temperature when 4moles of carbon dioxide occupies a 2 L container and exerts a pressure of 745torr?

10. What pressure, in atm, will be exerted by 1.25 moles of a gas at 39 Kelvin if it is contained in a 5 Liter vessel?

11. What volume will 29 grams of nitrogen gas occupy at 10 Celsius and a pressure of 620 torr?

12. A 35mL sample of hydrogen gas is collected over water at a temperature of 24oC, the vapor pressure of the water at that temperature is 2.99kPa, and the atmospheric pressure is 765.5 torr. What is the pressure of the dry hydrogen gas?

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Unit 8- Gas Laws


13. As the pressure of a gas at 2 atm is changed to 1 atm at constant temperature, the volume of the gas

a. decreases b. increases

c. remains the same

14. According to the kinetic molecular theory, molecules increase in kinetic energy when they a. Are mixed with other molecules at lower temperatureb. Are frozen into a solidc. Are condensed into a liquidd. Are heated to a higher temperature

15. Collide with each other in a container at lower temperature At STP, 32.0 liters of O2 contain the same number of molecules as

a. 22.4 L Ar b. 28.0 L of N2

c. 32. 0 L of H2 d. 44.8 L of He

16. What is the total pressure, in atmospheres, of a 10.0 L container that contains 10 moles of nitrogen gas and 10 moles of oxygen gas at 300 K?

a. 24.6 L c. 2460 Lb. 49.3 L d. 4930 L

17. An 8.25 L sample of oxygen is collected at 25°C and 1.022 atm pressure. What volume will the gas occupy 0.940 atm and -15°C?

a. 1.78 Lb. 5.00 L

c. 10.4 L d. 8.76 L

e. 7.77 L

18. A motorist fills his car tires to 32 lb/in2 pressure at a temperature of 30°C. Assuming no change in volume, what will be the pressure in the tires when the motorist drives across Death Valley, with a pavement temperature of 78°C?

a. 12 lb/in2 b. 28 lb/in2

c. 37 lb/in2 d. 4.8 lb/in2

e. 83 lb/in2

19. The mass of 2.37 liters of a gas is 8.91 grams. What is the density of the gas?a. 3.76 g/L b. 6.54 g/L

c. None of thesed. 0.266 g/L

e. 21.1 g/L

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Unit 8- Gas Laws

20. If temperature is constant, the relationship between pressure and volume isa. Direct b. inverse

21. A 268 cm3 sample of an ideal gas at 18°C and 748 torr pressure is placed in an evacuated container of volume 648cm3. To what centigrade temperature must the assembly be heated so that the gas will fill the whole chamber at 748 torr?

a. 431°C b. 120°C

c. 704°C d. 597°C

e. 324°C

22. How big a volume of dry oxygen gas at STP would you need to take to get the same number of oxygen molecules as there are hydrogen molecules in 25.0 liters at 0.850 atm and 35°C

a. 18.8 L b. 0.068 L

c. 0.656 L d. 4.2 L

e. 32.3 L

23. Nitrogen has a molar mass of 28.02 g/mol. What is the density of nitrogen at 1.05 atm and 37°C?

a. None of theseb. 2.82 g/L

c. 0.89 g/L d. 1.25 g/L

e. 4.72 g/cm3

24. How many moles of gas would it take to fill an average man's lungs, total capacity of which is about 4.5 liters? Assume 1.00 atm pressure and 37.0°C.

a. 37.0 molb. 1.24 mol

c. 0.75 mol d. 0.18 mole

e. 11.2 mol

25. Which flask contains the greatest number of molecules?

a. Flask 3 (O2) b. Flask 1 (NH3) c. Flask 2 (CH4)

d. Flasks 2 and 3 e. All are the same

134

Unit 8- Gas Laws

26. You have two samples of the same gas in the same size container, at the same pressure. The temperature in the first container is -23°C and the temperature in the second container is 227°C. What is the ratio of the number of moles of gas in the first container compared to that in the second container?

a. 2:1 b. 1:4

c. 1:2d. 1:1

e. 4:1

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Unit 8- Gas Laws

27. If pressure is constant, the relationship between temperature and volume isa. Direct b. Inverse

28. If pressure of a gas is increased and its volume remains constant, what will happen to its temperature?

a. Increase b. Decrease c. Stay the same

29. One way to increase pressure on a gas is toa. decrease temperatureb. increase volumec. increase the number of gas particlesd. lower the kinetic energy of the gas molecules

30. How do gas particles respond to an increase in volume?a. increase in kinetic energy and decrease in temperatureb. decrease in kinetic energy and decrease in pressurec. increase in temperature and increase in pressured. increase in kinetic energy and increase in temperature

31. If a gases volume is decreased and pressure is constant, its temperature willa. Increase b. Decrease c. Stay the same

32. If the temperature of a gas remains constant but pressure is decreased, the volume will a. Increase b. Decrease c. Stay the same

33. Convert 2.3 atm into mmHga. 2300 mmHgb. 1750 mmHg

c. 2.3 mmHgd. 0.0030 mmHg

34. The pressure of a gas is 750.0 torr when its volume is 400.0 mL. Calculate the pressure (in atm) if the gas is allowed to expand to 600.0 mL at constant temperature.

a. 0.660 atm b. 1.48 atm

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Unit 8- Gas Laws

c. 500.0 atm d. 1125 atm

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Unit 8- Gas Laws

35. The volume of a gas is increased from 150.0 mL to 350.0 mL by heating it. If the original temperature of the gas was 25.0 °C, what will its final temperature be (in °C)?

a. - 146°Cb. 10.7°C

c. 58.3°Cd. 422°C

e. 695°C

36. Standard temperature and pressure (STP) refers to which conditions? a. 0 oC and 1 kPa

b. 0 oC and 1 mm Hg

c. 0 K and 1 kPa

d. 0 K and 1 atm

e. 273 K and 1 atm

37. If 4 moles of a gas are added to a container that already holds 1 mole of gas, how will the pressure change within the container? (Assume volume and temperature are constant.)

a. The pressure will be 5 times as great.

b. The pressure will be 2 times as great.

c. The pressure will be 4 times as great.

d. The pressure will not change.

e. None of the above are correct.

38. A 4.0 L sample of hydrogen gas at 700 mm Hg would occupy what volume at 250 mm Hg? (Assume temperature and number of particles stays constant.)

a. 1.4 x 10 -7 Lb. 1.4 L

c. 11.2 L

d. 2.4 L

e. 7.0 x 10 5 L

39. A 25 L tank of oxygen under a pressure of 80. atm would require what pressure to decrease the volume to 1.0 L? (Assume temperature and number of particles stays constant.)

a. 0.31 atm b. 3.2 atm c. 2000 atm

d. There is not enough information to answer the question.

e. None of these is correct.

40. A balloon containing 2.50 L of gas at 1 atm would be what volume at a pressure of 300 KPa? (Assume temperature and number of particles stays constant.)

a. 6.33 L b. 8.11 L c. 0.844 L

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Unit 8- Gas Laws

d. 120. L e. 000833 L

41. A syringe containing 75.0 mL of air is at 298 K. What will the volume of the syringe be if it is placed in a boiling water bath (373 K). Assume pressure and the number of particles are held constant.

a. 59.9 mL b. 188 mL c. 300. mL

d. 8.34 x 106 mL e. None of the above are correct.

42. A gas occupies 40.0 mL at 127 oC. What volume will it occupy at -73 oC? (Assume pressure and number of particles is constant.)

a. 182 mL b. 8.80 mL c. 80.0 mL

d. 20.0 mL e. None of these is correct

43. If 88.0 grams of solid carbon dioxide evaporates, how many liters of CO2 gas will be formed at a temperature of 300 K and 2.00 atmospheres of pressure?

a. 98.5 liters b. 2170 liters

c. 24.6 liters d. 1080 liters

44. Which of the following equations correctly combines Boyle's and Charles' Laws?

a.

b.

c.

d.

e.

45. A 50.0 mL sample of a gas is at 3.00 atm of pressure and a temperature of 298 K . What volume would the gas occupy at STP?

a. 0.00728 mL

b. 15.3 mL

c. 18.2 mL

d. 137 mL

e. None of these is correct.

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Unit 8- Gas Laws

46. A syringe contains 60.0 mL of air at 740 mm Hg pressure and 20 oC. What would be the temperature at which the syringe would contain 30.0 mL at a pressure of 370 mm Hg? (Assume no gas could leak in or out of the syringe.)

a. -200 oC

b. 0.0137 oC

c. 5 oC

d. 73.3 oC

e. None of these is correct

47. A sealed container contains 1.0 mol of hydrogen and 2.0 moles of nitrogen gas. If the total pressure in the container is 1.5 atm, what is the amount of pressure exerted by each gas?

a. H2 = 1.0 atm and N2 = .50 atm

b. H2 = 0.50 atm and N2 = 1.0 atm

c. H2 = 1.0 atm and N2 = 2.0 atm

d. H2 = 2.0 atm and N2 = 1.0 atm

e. There is not enough information given to answer the question.

48. A sample of gas is collected by water displacement. The atmospheric pressure in the room is 757mm Hg and the vapor pressure of water is 17 mm Hg. What is the partial pressure of hydrogen under these conditions?

a. 17 mm Hg

b. 740 mm Hg

c. 757 mm Hg

d. 774 mm Hg

e. You cannot answer this question because you do not know the temperature.

140

Unit 9- Solids, Liquids and Phase Changes

SOLIDS AND LIQUIDS

States of Matter

There are ______ states of matter. A solid is a form of matter that has its own definite

_____________ and volume. A solid cannot _________________. The particles can vibrate but

cannot move around. The particles of matter in a solid are very tightly ____________________;

when heated, a solid expands, but only slightly. A liquid is a form of matter that flows, has

____________________ (definite) volume, and takes the _________________ of its container.

The particles in a liquid are not rigidly held in place and are _______________ closely packed

than are the particles in a solid; liquid particles are able to move past each other. A liquid is not

very __________________________. Like solids, liquids tend to expand when heated. A gas is

a form of matter that flows to conform to the ____________________ of its container and fills

the entire _______________________ of its container. Compared to solids and liquids, the

particles of gases are very far apart. Because of the significant amount of space between

particles, gases are easily compressed. _____________________ is composed of electrons and

positive ions at temperatures greater than ____________ °C. The sun and other stars are

examples of plasma.

Identify the following as a property of a solid, liquid or gas. The answer may include

more that one state of matter.

1. flows and takes the shape of a container

2. compressible

3. made of particles held in a specific arrangement

4. has definite volume

5. always occupies the entire space of its container

6. has a definite volume but flows

The word_____________________ refers to the gaseous state of a substance that is a solid or a

liquid at room temperature. For example, steam is a vapor because at room temperature water

exists as a liquid. Some substances are described as _______________________, which means

that they change to a gas easily at room temperature. Alcohol and gasoline are ______________

volatile than water. Kinetic-molecular theory predicts the constant motion of the liquid particles.

Individual liquid molecules do not have fixed positions in the liquid. However, forces of

141


________________________ between liquid particles limit their range of motion so that the

particles remain closely packed in a fixed volume. These attractive forces are called

___________________________ forces. Inter = between. Molecular = molecules. A liquid

diffuses more _______________________ than a gas at the same temperature, however, because

intermolecular attractions interfere with the flow. __________________________ is a measure

of the resistance of a liquid to flow. Viscosity decreases with ________________________

temperature. Particles in the middle of the liquid can be attracted to particles above them, below

them, and to either side. For particles at the surface of the liquid, there are no attractions from

above to balance the attractions from _______________. Thus, there is a net attractive force

pulling down on particles at the surface. _____________________ ____________________ is a

measure of the inward pull by particles in the interior. Soaps and detergents decrease the surface

tension of water by disrupting the _______________________ bonds between water molecules.

For a substance to be a solid rather than a liquid at a given temperature, there must be strong

attractive forces acting between particles in the solid. These forces limit the motion of the

particles to __________________________ around fixed locations in the solid. Thus, there is

more order in a solid than in a liquid. The particles can only vibrate and revolve in place.

Because of this order, solids are much less _________________ than liquids and gases. In fact,

solids are not classified as fluids. Most solids are more _________________ than most liquids.

A crystalline solid is a solid whose atoms, ions, or molecules are arranged in an orderly,

geometric, three-dimensional structure. Most solids are _____________________. Amorphous

solids lack an orderly internal structure. Think of them as __________________________

liquids. Examples of amorphous solids include ____________________ and glass.

Phase Changes

If a substance is usually a liquid at room temperature (as water is), the gas phase is called a

_________________. Vaporization is the process by which a liquid changes into a gas or vapor.

Vaporization is an endothermic process - it requires _______________. When vaporization

occurs only at the _____________________ of an uncontained liquid (no lid on the container),

the process is called evaporation. Molecules at the surface break away and become gas. Only

those with enough _____________________ energy (KE) escape. Evaporation is a

_______________________ process. It requires heat, which is endothermic.

142


__________________ pressure is the pressure exerted by a vapor over a liquid. As temperature

increases, water molecules gain kinetic energy and vapor pressure ______________________.

When the vapor pressure of a liquid equals atmospheric pressure, the liquid has reached its

boiling point, which is 100°C for water at sea level. Recall that standard atmospheric pressure

equals ______ atm. At this point, molecules throughout the liquid have the energy to enter the

gas or vapor phase. The temperature of a liquid can never ______________ above its boiling

point. Boiling is an __________________________ process. It requires the addition of heat.

As you go up into the mountains (increase in elevation), atmospheric pressure ______________.

Lower external pressure requires ______________________ vapor pressure. Lower vapor

pressure means lower ______________________ point. As a result, spaghetti cooks slower in

the mountains than at the beach. When you use a pressure cooker to can vegetables, the external

pressure around the mason jars rises. This raises the vapor pressure needed in order for water to

boil. In turn, the boiling point is raised so the food cooks ______________________.

Some phase changes release energy into their surroundings. For example, when a vapor loses

energy, it may change into a __________________. Condensation is the process by which a gas

or vapor becomes a liquid. It is the ___________________ of vaporization. In a closed system,

the rate of vaporization can equal the rate of condensation. When first sealed, the molecules

gradually _________________ the surface of the liquid. As the molecules build up above the

liquid, some condense back to a liquid. Equilibrium is reached when the rate of vaporization

__________________ the rate of condensation. Molecules are constantly changing phase. The

total amount of liquid and vapor remains _______________________.

The melting point of a solid is the temperature at which the ____________________ holding the

particles together are broken and the solid becomes a liquid. When heated the particles vibrate

more _____________________ until they shake themselves free of each other. The freezing

point is the temperature at which a liquid becomes a _________________________ solid. The

freezing point is the _______________ as the melting point. The process by which a solid

changes directly into a gas without first becoming a liquid is called _______________________.

Solid air fresheners and dry ice are examples of solids that sublime. When a substance changes

from a gas or vapor directly into a solid without first becoming a liquid, the process is called

143


_________________________. Deposition is the reverse of sublimation. _______________ is

an example of water deposition.

Classify the following phase changes.

1. dry ice (solid carbon dioxide) to carbon dioxide gas ____________________________

2. ice to liquid water ________________________________

3. liquid water to ice ________________________________

4. water vapor to liquid water ________________________________

Phase Diagrams

Temperature and _____________________ control the phase of a substance. A phase diagram is

a graph of pressure versus temperature that shows in which phase a substance exists under

different conditions of temperature and pressure. A phase diagram typically has ______ regions,

each representing a different phase and three curves that ________________________ each

phase.

The points on the curves (lines) indicate conditions under which two phases coexist. The critical

point indicates the critical pressure and the critical temperature above which a substance cannot

exist as a ____________________. The triple point is the point on a phase diagram that

represents the temperature and pressure at which three phases of a substance can

__________________________. The __________________________ slope of the solid-liquid

line in the phase diagram for water indicates that the solid floats on its liquid.

144

0.0098Temperature (°C)


What happens to solid CO2 at -100 ºC and 1 atm pressure as it is heated to room

temperature?

What happens to water at 1 atm as the temperature rises from -15°C to 60°C?

What state of matter is water at 50°C and 20 atm?

At what temperature does the triple point occur for water?

At what temperature does the critical point occur for carbon dioxide?

At standard pressure and -78°C, what phase change occurs for carbon dioxide?

What state of matter is carbon dioxide at -80°C and 2 atm?

Solids and Liquids Practice Test

Directions: Identify the proper sections by indicating the interval between 2 letters.

1. Which section represents the gas being warmed? _____ to _______

2. Which section represents a phase change from solid to liquid? _____ to _______

3. Define viscosity-

4. The temperature at which the vapor pressure of a liquid equals the external or atmospheric pressure is known as the________________________

145

A

B

C

D E

F

G

H

200º C

60º C

Heating Curve

Energy


Directions: Using the phase diagram

below, answer questions 5-7:

5. What does letter T represent?

_______________

6. At 0.75 atm, what is the

MP_____and BP______

7. At 0.25 atm, what is the freezing

point? ________

Multiple Choice

8. Under the same conditions of temperature and pressure, a liquid differs from a gas because the particles of the liquid

a. are in constant straight-line motion b. take the shape of the container they occupy c. have no regular arrangement d. have stronger forces of attraction between them

9. The phase change represented by the equation I2 (s) ----> I2 (g) is calleda. sublimation b. condensation

c. melting d. boiling

10. Which of the following terms represents the temperature and pressure at which three states of a compound can coexist

a. Law of definite compositionb. Van der Waals forcesc. Graham’s Law of Diffusion

d. Triple pointe. Critical point

11. What is the smallest portion of a crystal lattice that reveals the 3-dimensional pattern?a. unit cellb. crystal structure

c. coordinate systemd. crystalline symmetry

146

Temperature (oC)

Pressure(atm)

T

C

0.25

0.75

125 175 250


12. What forces hold nonpolar particles together?a. magicb. hydrogen bonding

c. London dispersiond. dipole-dipole

13. Compared with the particles in a solid, the particles in a liquid usually area. higher in energyb. closer together

c. more massived. less fluid

14. What is the process of a substance changing from a vapor to a solid without passing through the liquid phase?

a. condensationb. deposition

c. sublimationd. evaporation

15. A liquid forms when the average energy of a solid substance's particlesa. increasesb. changes form

c. creates an orderly arrangement

d. decreases

16. Which of the following is an NOT an amorphous solid?a. silly puttyb. play dough

c. iced. glass

17. Which term best describes the process by which particles escape from both the surface of a liquid and from within the liquid itself and enter the gas phase?

a. boilingb. evaporation

c. aerationd. surface tension

18. The attractive forces in a solid area. too weak to prevent the particles from changing positionsb. strong enough to hold the particles in fixed positionsc. less effective than those in a liquidd. weaker than those of a liquid particles

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19. When electrons in a covalent bond spend more time around on nucleus of the compound than the other, the molecule is considered

a. weakb. polar

c. ionicd. nonpolar

20. Which of the following phase changes results in an overall increase in randomness of particles over the course of the change?

a. depositionb. condensation

c. meltingd. freezing

21. What type of crystals are like giant molecules?a. covalent networkb. covalent molecular

c. metallicd. ionic

22. The difference between crystalline and amorphous solids is determined bya. temperature changesb. pressure when the substances are formedc. strength of molecular forcesd. the particle arrangement

23. Which of the following statements is false?a. Condensed states have much higher densities than gases.b. Molecules are very far apart in gases and closer together in liquids and solids.c. Gases completely fill any container they occupy and are easily compressed.d. Vapor refers to a gas formed by evaporation of a liquid or sublimation of a solid.e. Solid water (ice), unlike most substances, is denser than its liquid form (water).

24. Which physical state/ property is incorrectly matched?a. liquids and solids - rigid

shapeb. gases - easily compressedc. gases and liquids – flow

d. solids - higher density than gases

e. liquids – incompressible

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25. Which one of the following statements does not describe the general properties of liquids accurately?

a. Liquids have characteristic volumes that do not change greatly with changes in temperature. (Assuming that the liquid is not vaporized.)

b. Liquids have characteristic volumes that do not change greatly with changes in pressure

c. Liquids diffuse only very slowly when compared to solids.d. The liquid state is highly disordered compared to the solid state.e. Liquids have high densities compared to gases.

26. For which of the following would permanent dipole-dipole interactions play an important role in determining physical properties in the liquid state?

a. BF3

b. ClFc. BeCl2

d. F2

e. CCl4

27. Identify which property liquids do not have in common with solids.a. rigid shapeb. volumes do not change significantly with pressurec. hydrogen bonding forces can be significantd. practically incompressiblee. volumes do not change significantly with temperature

28. Which one of the following statements does not describe the general properties of solids accurately?

a. Solids have characteristic volumes that do not change greatly with changes in temperature.

b. Solids have characteristic volumes that do not change greatly with changes in pressure.

c. Solids diffuse only very slowly when compared to liquids and gases.d. Solids are not fluid.e. Most solids have high vapor pressures at room temperature.

29. Which of the following interactions are the strongest?a. hydrogen bonding forceb. ion-ion interactions

c. dipole- dipole forced. London-dispersion force

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30. For which of the following would dispersion forces be the most important factor in determining physical properties in the liquid state?

a. H2Ob. NaCl

c. F2

d. HFe. NH4Cl

31. For which of the following would hydrogen bonding not be an important factor in determining physical properties in the liquid state?

a. HIb. H2O

c. HFd. NH3

e. H2O2

150


32. Which one of the following statements does not describe the general properties of liquids accurately?

a. In the liquid state the close spacing of molecules leads to large intermolecular forces that are strongly dependent on the nature of the molecules involved.

b. Liquids are practically incompressible.c. As the temperature of a liquid is increased, the vapor pressure of the liquid

decreases.d. The normal boiling point of a liquid is the temperature at which the vapor

pressure of the liquid becomes equal to exactly 760 torr.e. Vapor pressures of liquids at a given temperature differ greatly, and these

differences in vapor pressure are due to the nature of the molecules in different liquids.

33. Which technique listed below separates a mixture of liquids on the basis of their boiling points?

a. Distillationb. Extractionc. Filtration

d. Refluxe. None of the above

34. The melting point of a solid is the same as the ____ of its liquid.a. Boiling pointb. Freezing pointc. Sublimation point

d. Condensation pointe. Critical point

35. Some solids can be converted directly to the vapor phase by heating. The process is called ____.

a. Fusionb. Sublimationc. Vaporization

d. Condensatione. Distillation

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36.Which of the images shown here depicts a phase that has definite volume but not definite shape?

a. The one on the left

b. The one in the middle

c. The one on the right

37.Which phase depicted here has both a definite shape and a definite volume?

a. The one in the middleb. The one in the middle and the one on the rightc. The one on the rightd. The one on the left

38.Which of the phases depicted here can be easily compressed?

a. The one in the middleb. The one on the rightc. The one on the left

d. The one in the middle and the one on the right

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39. Which phase of matter is depicted here?a. Liquidb. Gas

c. Plasmad. Solid

40. Ice floats in water because:a. Water is denser than iceb. Ice is colder than waterc. Water has a substantial surface tensiond. Ice is denser than water

41.Which phase(s) depicted here have the ability to flow?

a. The one on the rightb. The one on the leftc. The ones on the right and the leftd. The one in the middle and the one on the righte. The one in the middle

42. During the phase change from liquid to solid:a. energy must be removedb. energy must be absorbedc. there is no change in energy

43. Definite shape, definite volume, and a low rate of diffusion are characteristics of:a. Fluidsb. Liquids

c. Gasesd. Solids

153


44. Which phase of matter is depicted here?a. Solidb. Gas

c. Liquidd. Plasma

154

Unit 10- Solutions and Solubility

SOLUTIONS

A solution is made up of a solute and a _______________________________. The solvent does

the ________________________________. The solute is the substance that is dissolved. If a

solution is made of two liquids, the one in ______________________ quantity is the solute.

_________________________ is the universal solvent. Water is a versatile solvent because of

its attraction to other molecules and its ___________________________. Most of the water on

the Earth is not pure, but rather is present in solutions. Table salt (NaCl), like a great many ionic

compounds, is _________________________ in water. The salt solution is also an excellent

___________________________ of electricity. This high level of electrical conductivity is

always observed when ionic compounds dissolve to a significant extent in water. The process by

which the charged particles in an ionic solid separate from one another is called

_____________________________. You can represent the process of dissolving and

dissociation in shorthand fashion by the following equation.

________________________________________ Water is not only good at dissolving ionic

substances. It also is a good solvent for many _________________________________

compounds. Consider the covalent substance sucrose, commonly known as table sugar, as an

example. Although water dissolves an enormous variety of substances, both ionic and covalent,

it does not dissolve everything. The phrase that scientists often use when predicting solubility is

“________________ dissolves like.” The expression means that dissolving occurs when

similarities exist between the solvent and the solute. A salt dissolves faster if it is

_________________________ or shaken, if the particles are made

___________________________ and if the temperature is ___________________________. In

order to dissolve the solvent molecules must come in ______________________________ with

the solute. Stirring moves fresh _____________________________ next to the solute. The

solvent touches the surface of the solute. __________________________________ pieces

increase the amount of surface of the solute. For solids in liquids, as the temperature goes up the

solubility goes ______________________. A higher temperature makes the molecules of the

solvent move around ______________________________ and contact the solute harder and

________________________ often. It speeds up dissolving. Higher temperature usually

increases the _______________________________ that will dissolve.

155


Figure 1

How many grams of sodium hydroxide (NaOH) will dissolve in 100 g of water at 15ºC?

How many grams of sodium hydroxide will dissolve in 100 g of water at 40ºC?

At what temperature will 90 grams of Pb(NO3)2 dissolve in 100 g of water?

At what temperature will 30 grams of KNO3 dissolve in 100 g of water?

For gases in a liquid, as the temperature goes up the solubility goes _______________________.

For gases in a liquid, as the pressure goes up the solubility goes ______________________.

Solubility is the ________________________________ amount of substance that will dissolve

at that temperature (usually measured in grams/liter). If the amount of solute dissolved is less

than the maximum that could be dissolved, the solution is called a(n)

___________________________ solution. A solution which holds the maximum amount of

solute per amount of the solution under the given conditions is called a(n)

_____________________________ solution. A(n) _________________________________

solution contains more solute than the usual maximum amount and are unstable. They cannot

permanently hold the excess solute in solution and may release it suddenly. A(n)

__________________ crystal will make the extra come out. Generally, a supersaturated solution

156


is formed by dissolving a solute in the solution at an elevated temperature, at which solubility is

_______________________ than at room temperature, and then slowly cooling the solution.

Figure 2

If 45 g of KCl is dissolved in 100 g of water at 60ºC, is the solution unsaturated, saturated

or supersaturated?

If 90 g of Pb(NO3)2 is dissolved in 100 g of water at 40ºC, is the solution unsaturated,

saturated or supersaturated?

If 30 g of KNO3 is dissolved in 100 g of water at 20ºC, is the solution unsaturated,


If 10 g of KClO3 is dissolved in 100 g of water at 50ºC, is the solution unsaturated,


___________________________ means that two liquids can dissolve in each other.

________________________________ means they cannot. Oil and ______________________

are immiscible.

157


Measuring Solutions

Chemists never apply the terms strong and weak to solution concentrations. Instead, use the

terms concentrated and _________________________. Concentration is a measure of the

amount of solute dissolved in a certain amount of solvent. A concentrated solution has a

_________________________ amount of solute. A dilute solution has a

__________________________ amount of solute. For chemistry applications, the concentration

term molarity is generally the most useful. Molarity is the number of moles of

_______________________ in 1 Liter of the solution.

moles

Molarity = -------------------------

Liters of solution

Note that the volume is the total solution volume that results, not the volume of solvent alone.

Suppose you need 1.0 Liter of a 1 M copper (II) sulfate solution.

STEP 1: Measure a mole of copper (II) sulfate.

STEP 2: Place the CuSO4 in a volumetric flask.

STEP 3: Add some water to dissolve the CuSO4 and then add enough additional water to

bring the total volume of the solution to 1.0 L.

What is the molarity of a solution with 2.0 moles of NaCl in 4.0 Liters of solution?

What is the molarity of a solution with 3.0 moles dissolved in 250 mL of solution?

How many moles of NaCl are needed to make 6.0 L of a 0.75 M NaCl solution?

0.200 moles of NaOH are dissolved in a small amount of water then diluted to 500. mL.

What is the concentration?

1.25 moles of NaCl are dissolved in a small amount of water then diluted to 625 mL.


How many moles are in 2.00 L of a 3.00 M solution of sulfuric acid (H2SO4)?

How many moles are in 1500 mL of a 3.2 M solution of nitric acid (HNO3)?

10.3 g of NaCl are dissolved in a small amount of water then diluted to 250 mL. What is

the concentration?

20.3 g of NaOH are dissolved in a small amount of water then diluted to 500. mL. What

is the concentration?

158


80.6 g of KCl are dissolved in a small amount of water then diluted to 500. mL. What is

the concentration?

125 g of NaC2H3O2 are dissolved in a small amount of water then diluted to 750. mL.


How many grams of CaCl2 are needed to make 625 mL of a 2.00 M solution?

How many grams of sugar are needed to make 125 mL of a 0.500 M C6H12O6 solution?

How many grams of sodium hydroxide are needed to make 500. mL of a 0.750 M NaOH

solution?

How many grams of aluminum nitrate are needed to make 600. mL of a 0.500 M

Al(NO3)2 solution?

Refer to Figure 1 to answer the following questions:

What is the molarity of a KNO3 solution at 10ºC? (100 g of water = 100 mL of water)

What is the molarity of a Pb(NO3)2 solution at 61ºC?

What is the molarity of a KNO3 solution at 71ºC?

Dilution

The number of moles of solute doesn’t change if you add more solvent.

M1 x V1 = M2 x V2

M1 and V1 represent the starting concentration and volume. M2 and V2 represent the

______________ concentration and volume.

2.0 L of a 0.88 M solution are diluted to 3.8 L. What is the new molarity?

6.0 L of a 0.55 M solution are diluted to 8.8 L. What is the new molarity?

You have 150 mL of 6.0 M HCl. What volume of 1.3 M HCl can you make?

6.0 liters of a 0.55 M solution are diluted to a 0.35 M solution. What is the final volume?

You need 450 mL of 0.15 M NaOH. All you have available is a 2.0 M stock solution of

NaOH. How do you make the required solution?

Compounds in Aqueous Solution and Double Replacement Reactions

159


The _________________________________ of ions when an ionic compound dissolves in

water is called dissociation. Although no compound is completely insoluble, compounds of

very low solubility can be considered insoluble.

Using the solubility rules printed on page 6 of the NCDPI Reference Tables for

Chemistry, determine whether the following salts are soluble in water.

a) sodium chloride _____________________

b) mercury (I) acetate _____________________

c) potassium nitrate _____________________

d) nickel carbonate _____________________

e) barium sulfate _____________________

f) ammonium bromide ____________________

g) calcium sulfide _____________________

In a double-replacement reaction, two compounds exchange partners with each other to produce

two different compounds. The general form of the equation is

AB + CD ---> AD + CB

Signs that a double-replacement reaction has taken place include a color change, the release or

absorption of energy, evolution of a gas, and formation of a

_______________________________.

Write the net ionic equation for each of the following precipitation reactions.

a) barium chloride + silver nitrate ___________________________________________

b) lead (II) nitrate + potassium iodide _______________________________________

c) ammonium sulfate + barium nitrate _______________________________________

d) potassium sulfide + zinc acetate __________________________________________

e) strontium phosphate + aluminum hydroxide __________________________________

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Homework / Practice

1. Suppose you had 2.00 moles of solute dissolved into 1.00 L of solution. What's the

molarity?

2. Calculate the molarity of 25.0 grams of KBr dissolved in 750.0 mL.

3. 80.0 grams of glucose (C6H12O6, mol. wt = 180. g/mol) is dissolved in enough water to

make 1.00 L of solution. What is its molarity?

4. What is the molarity when 0.75 mol is dissolved in 2.50 L of solution

5. What is the molarity of 245.0 g of H2SO4 dissolved in 1.00 L of solution?

6. What is the molarity of 5.00 g of NaOH in 750.0 mL of solution?

7. How many moles of Na2CO3 are there in 10.0 L of 2.0 M soluton?

8. How many moles of Na2CO3 are in 10.0 mL of a 2.0 M solution?

9. How many grams of Ca(OH)2 are needed to make 100.0 mL of 0.250 M solution?

10. What is the molarity of a solution made by dissolving 20.0 g of H3PO4 in 50.0 mL of

solution?

11. What weight (in grams) of KCl is there in 2.50 liters of 0.50 M KCl solution?

12. What is the molarity of a solution containing 12.0 g of NaOH in 250.0 mL of solution?

13. Determine the number of moles of solute to prepare these solutions:

a. 2.35 liters of a 2.00 M Cu(NO3)2 solution.

b. 16.00 mL of a 0.415-molar Pb(NO3)2 solution.

c. 3.00 L of a 0.500 M MgCO3 solution.

d. 6.20 L of a 3.76-molar Na2O solution.

14. Determine the final volume of these solutions:

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e. 4.67 moles of Li2SO3 dissolved to make a 3.89 M solution.

f. 4.907 moles of Al2O3 to make a 0.500 M solution.

g. 0.783 grams of Na2CO3 to make a 0.348 M solution.

h. 8.97 grams of (NH4)2CO3 to make a 0.250-molar solution.

i. 48.00 grams of PbCl2 to form a 5.0-molar solution.

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Solutions Practice Test

Directions: For credit, show all steps in your calculations and include units.1. What is the molarity of a solution of NaOH if 12 liters of the solution contains 3 moles of

NaOH?

2. You have a 3.5 L solution that contains 20 grams of NaCl. What is the molarity of the solution?

For these common substances, identify what is the solute and solvent.

Solute Solvent

3. KoolAid (sugar, water)4. Vinegar (acetic acid, water)

Determine whether, according to the solubility rules, the mixing of these substances will make a solution.

Yes No

5. Water and Mg(OH)2

6. Water and Na2CO3

Determine how the following conditions can affect the rate of dissolving KCl in water.

Faster Slower

7. Decrease the temperature of the water8. Agitate the mixture

Directions: Using the solubility curve below, answer the following questions.

9. Which is most soluble at 40ºC?

_______

10. How many grams of KClO3 can

be dissolved in 100g H2O at

90ºC? _____

11. At 40ºC, how much HCl can be

dissolved in 300 g. H2O?

_________

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Multiple Choice

12. Which of these compounds are soluble in water?f. CaBr2

g. PbCl2

h. SrSi. CaCO3

13. Which of these compounds is insoluble in water?a. CuIb. CaCl2

c. MgSd. NaBr

14. Iron (III) sulfide is soluble in water.a. True b. False

15. LiBr isa. Solubleb. Insoluble

c. can't tell the solubilityd. a covalent compound

16. NH4OH is insoluble.a. True b. False

17. Which of these compounds is soluble?a. Pb(OH)4

b. NaHCO3

c. BaCrO4

d. Mg3(PO4)2

18. Powdered NaCl will dissolve slower then NaCl crystals because there is less surface area for the reaction to take place.

a. True b. False

19. Which term indicates that there is a large quantity of solute, compared to the amount of solvent in a solution

a. Diluteb. Concentrated

c. Unsaturatedd. Saturated

20. Ten grams of sodium hydroxide is dissolved in enough water to make 1L of solution. What is the molarity of the solution?

a. 0.25 Mb. 0.5 M

c. 1 Md. 1.5 M

21. Which solution is the most concentrated?a. 1 mole of solute dissolved in 1 liter of solution? b. 2 moles of solute dissolved in 3 liters of solution? c. 6 moles of solute dissolved in 4 liters of solution? d. 4 moles of solute dissolved in 8 liters of solution?

164


22. What is the total number of moles of H2SO4 needed to prepare 5.0 liters of a 2.0 M solution of H2SO4?

a. 2.5

b. 5.0 c. 10

d. 20

23. What is the molarity of a KF (aq) solution containing 116 grams of KF in 1.00 liter of solution?

a. 1.00 M b. 2.00 M

c. 3.00 M d. 4.00 M

24. The solubility of a gas will _?_ when a solution containing the gas is heated and the solubility of a gas in a solution will _?_ when the pressure over the solution is decreased.

a. decrease...decrease b. decrease...increase

c. increase...decrease d. increase...increase

25. How many grams of potassium nitrate are required to prepare 3.00 x 102 mL of 0.750 M solution?

a. 2.28 x 104 g b. 84.5 gc. 22.8 g

d. 2.4 g e. 0.00223 g

26. How many grams of sodium chloride are dissolved in 50.0 mL of 1.50 M solution?a. 0.00324 gb. 117 g c. 4.38 x 103 g

d. 23.4 g e. 4.38 g

27. A 500 mL sample of a 0.350 M solution is left open on a lab counter for two weeks, after which the concentration of the solution is 0.955 M. What is the new volume of the solution?

a. 183 L b. 223 mL c. 0.183 L

d. 1.83 mL e. 0.605 L

28. A chemist makes a stock solution of potassium chromate solution by dissolving 97.1 grams of the compound in 1.00 liter of solution. What volume of the solution must be diluted with water in order to prepare 200. mL of 0.200 M solution?

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a. 80.0 mL b. 0.150 L c. 750. mL

d. 0.0800 mL e. 120. mL

29. A 25.0-g sample of sodium hydroxide is dissolved in 400. mL of water. What is the concentration of the solution?

a. 0.10 M b. 62.5 M c. 1.56 M

d. 100. Me. 1.56 x 10-3 M

30. How many milliliters of 6.0 M HNO3 are needed to prepare 500 mL of 0.50 M HNO3?a. 0.25 mL b. 300 mL

c. 15.76 mL d. 40 mL

e. None of these are correct

31. How many grams of calcium chloride are needed to prepare 300 mL of a 0.250 M solution?

a. 832 g b. 5.66 g

c. 566 g d. 8.32 g

e. 112 g

32. In a solution of sugar and water, the solvent is the:a. sugar b. water

33. In a solution of sugar and water, the solute is the:a. sugar b. water

34. Gases dissolve best in liquids when:a. the pressure is high and the temperature is lowb. the pressure is low and the temperature is lowc. the pressure is low and the temperature is highd. the pressure is high and the temperature is high

166


35. The solubility of potassium nitrate in water at 35 °C is about 60 grams KNO3 per 100 grams of water. How many grams of KNO3 should dissolve in 300 grams of water at 35 °C?

a. 180 grams b. 335 grams c. 20 grams

36. Breaking up a solid speeds dissolving in a liquid by:a. decreasing the pressureb. slowing hydrationc. raising the temperatured. increasing surface area

167

37. Most salts become more soluble in water as the:

a. temperature is decreasedb. pressure is decreased

c. pressure is increasedd. temperature is increased

38. Calculate the concentration of the following solution in units of molarity, M , moles per liter:

80 grams of NaOH is dissolved in 2 L of solution

a. 40 M NaOHb. 82 M NaOH

c. 1 M NaOHd. 160 M NaOH

39. How many grams of NaOH are needed to make 100 milliliters of a 0.2 molar solution of NaOH?

a. 0.002gramsb. 0.8grams

c. 20gramsd. 800grams

40. How many milliliters of 2 M NaCl solution are required to make 1 liter of 0.4 M NaCl solution?

a. 5,000 mLb. 800 mL

c. 200 mLd. 0.2 mL

41. Which procedure will increases the solubility of KCl in water?a. stirring the solute and solvent mixture b. increasing the surface area of the solute c. raising the temperature of the solvent d. increasing the pressure on the surface of the solvent

42. Under which conditions are gases most soluble in water?a. high pressure and high temperature b. high pressure and low temperature c. low pressure and high temperature d. low pressure and low temperature

Unit 11- Acids and Bases

Acids and Bases

Properties of Acids and Bases

Acids taste _________________. Lemon juice and _____________________________, for

example, are both aqueous solutions of acids. Acids conduct electricity; they are

________________________. Some are strong electrolytes, while others are

_________________ electrolytes. An acetic acid solution, which is a weak electrolyte, contains

only a few ions and does not conduct as much current as a strong electrolyte. The bulb is only

_____________________ lit. Acids cause certain colored dyes

(_________________________) to change color. (Litmus paper turns _______________.)

Acids react with metals to form ______________________________ gas. This property

explains why acids corrode most metals. Acids react with hydroxides (bases) to form water and

a ___________________. Bases taste _________________________ and feel

_______________________________. Bases can be strong or weak electrolytes.

Naming Acids

Acids are compounds that give off _________________________ ions (H+) when dissolved in

water. Acids will always contain one or more hydrogen ions next to an

__________________________. The anion determines the name of the acid.

Naming Binary AcidsBinary acids contain hydrogen and an anion whose name ends in –ide. When naming the acid,

put the prefix ______________________- and change -ide to -ic acid.

Example: HCl The acid contains the hydrogen ion and chloride ion. Begin with the prefix hydro-, name the nonmetallic ion and change -ide to -ic acid.Example: H2S The acid contains the hydrogen ion and sulfide ion. Begin with the prefix hydro- and name the nonmetallic ion. The next step is change -ide to -ic acid, but for sulfur the “ur” is added before -ic. Name the following binary acids.

a) HF ___________________________________________

b) H3P __________________________________________

Writing the Formulas for Binary AcidsThe prefix hydro- lets you know the acid is binary. Determine whether you need to criss-cross the oxidation numbers of hydrogen and the nonmetal.

169


Example: Hydrobromic acid The acid contains the hydrogen ion and the bromide ion. The two oxidation numbers add together to get zero. The prefix hydro- lets you know the acid is binary.Example: Hydrotelluric acid The acid contains the hydrogen ion and the telluride ion. The two oxidation numbers do NOT add together to get zero, so you must criss-cross. Write the formulas for the following binary acids.

a) Hydrocyanic acid _______________ b) Hydroselenic acid _______________

Naming Ternary AcidsThe acid is a ternary acid if the anion has oxygen in it. The anion ends in -ate or -ite. Change the suffix -ate to -_______ acid. Change the suffix -ite to -ous acid The hydro- prefix is NOT used!Example: HNO3 The acid contains the hydrogen ion and nitrate ion. Name the polyatomic ion and change -ate to -ic acid.Example: HNO2 The acid contains the hydrogen ion and nitrite ion. Name the polyatomic ion and change -ite to -ous acid.Example: H3PO4 The acid contains the hydrogen ion and phosphate ion. Name the polyatomic ion and change -ate to -ic acid. Name the following ternary acids.

a) H2CO3 ___________________________________________________

b) H2SO4 ___________________________________________________

c) H2CrO4 ___________________________________________________

d) HClO2 ___________________________________________________

Writing the Formulas for Ternary AcidsThe lack of the prefix hydro- from the name implies the acid is ternary, made of the hydrogen ion and a polyatomic ion. Determine whether you need to criss-cross the oxidation numbers of hydrogen and the polyatomic ion.Example: Acetic acid The polyatomic ion must end in –ate since the acid ends in -ic. The acid is made of H+ and the acetate ion. The two charges when added equal zero.Example: Sulfurous acid Again the lack of the prefix hydro- implies the acid is ternary, made of the hydrogen ion and a polyatomic ion. The polyatomic ion must end in –ite since the acid ends in -ous. The acid is made of H+ and the sulfite ion. The two charges when added do not equal zero, so you must crisscross the oxidation numbers. Write the formulas for the following ternary acids.

a) perchloric acid ______________________ b) iodic acid _____________________

c) nitrous acid _______________________ d) bromic acid ___________________

Types of Acids and Bases

170


Arrhenius Definitions - The simplest definition is that an acid is a substance that produces

_____________________________ ions when it dissolves in water. A hydronium ion, H3O+,

consists of a hydrogen ion attached to a __________________ molecule. A hydronium ion,

H3O+, is equivalent to H+. HCl and H3PO4 are acids according to Arrhenius. A base is a

substance that produces ________________________ ions, OH–, when it dissolves in water.

Ca(OH)2 and NaOH are Arrhenius bases. NH3, ammonia, could not be an Arrhenius

___________________.

Monoprotic acids have only ____________ ionizable hydrogen. Some acids have more than one

ionizable hydrogen and are called ______________________________ acids.

Bronsted-Lowry Definitions - An Bronsted-Lowry acid is a ________________________ (H+)

donor. HBr and H2SO4 are Bronsted-Lowry acids. When a Bronsted-Lowry acid dissolves in

water it gives its proton to water. HCl (g) + H2O (l) ↔ H3O+ + Cl- A Bronsted-Lowry base

is a proton acceptor. B + H2O ↔ BH+ + OH- A Brønsted-Lowry base does

not need to contain OH-.

Consider HCl(aq) + H2O(l) ® H3O+(aq) + Cl-(aq) HCl donates a proton to water.

Therefore, HCl is an _______________. H2O accepts a proton from HCl. Therefore, H2O is a

______________.

Identify the acid and base in the following reactions.

a) H2SO3 + H2O ↔ HSO3- + H3O+

Acid _____________________________ base _________________________

b) NH3 + H2SO4 ↔ NH4+ + HSO4

-

Acid _____________________________ base _________________________

Molarity and DilutionThe concentration of a solution is the amount of solute present in a given quantity of solution.

_________________________ is the number of moles of solute in 1 liter of solution.

moles soluteMolarity = --------------------------

liters of solutionThe procedure for preparing a less concentrated solution from a more concentrated one is called

a ___________________________.

M1 V1 = M2 V2

PRACTICE:

171


What is the molarity of an acetic acid (HC2H3O2) solution with 4.0 moles dissolved in 250 mL of solution?

How many moles of hydrochloric acid (HCl) are needed to make 3.0 L of a 0.55 M HCl solution?

0.600 moles of the base sodium hydroxide (NaOH) are dissolved in a small amount of water then diluted to 500. mL. What is the concentration?

3.25 moles of the base potassium hydroxide (KOH) are dissolved in a small amount of water then diluted to 725 mL. What is the concentration?

How many moles are in 2.00 L of a 6.00 M solution of sulfuric acid (H2SO4)?

How many moles are in 1250 mL of a 3.60 M solution of nitric acid (HNO3)?

6.0 L of a 1.55 M LiOH solution are diluted to 8.8 L. What is the new molarity of the lithium hydroxide solution?

You have 250 mL of 6.0 M HCl. How many milliliters of 1.2 M HCl can you make?

4.0 liters of a 0.75 M solution of sulfuric acid (H2SO4) are diluted to a 0.30 M solution. What is the final volume?

You need 350 mL of 0.25 M NaOH. All you have available is a 2.0 M stock solution of NaOH. How do you make the required solution?

Strength of Acids and BasesThe strength of a base is based on the percent of units

___________________________________, not the number of OH– ions produced. The strength

of a base does NOT depend on the _____________________________. 1A and _______

hydroxides, excluding __________, are strong bases. Some bases, such as Mg(OH)2, are not

very soluble in water, and they don’t produce a large number of OH– ions. However, they are

still considered to be strong bases because all of the base that does dissolve completely

dissociates. The strength of an acid is based on the percent of units dissociated, not the number

of ____________ ions produced. The strength of an acid does NOT depend on the

_______________________________. There are 6 strong acids: HCl, HBr, HI, HClO4, HNO3,

and H2SO4. Strong acids and bases are strong __________________________________ because

they dissociate completely. Electrolytes conduct ______________________________. Weak

acids and bases don’t completely ionize, so they are weak electrolytes. Although the terms weak

172


and strong are used to compare the _____________________________ of acids and bases,

dilute and concentrated are terms used to describe the _____________________________ of

solutions.

pH ScaleWater ionizes; it falls apart into _________________. H2O H+ + OH- The preceding reaction

is called the _____________________________________ of water. [H+ ] = [OH-] = 1 x 10-7 M

When [H+ ] = [OH-], the solution is _________________________. At 25°C,

Kw = [H+] [OH-] = 1 x 10-14 Kw is called the ion-product constant. If [H+] > 10-7 then [OH-] < 10-

7. The solution is ______________________ when [H+] > [OH-]. If [H+] < 10-7 then [OH-] >

10-7. The solution is __________________________ when [OH-] > [H+]. In most applications,

the observed range of possible hydronium or hydroxide ion concentrations spans 10–14 M to

______M. To make this range of possible concentrations easier to work with, the pH scale was

developed. pH is a mathematical scale in which the concentration of hydronium ions in a

solution is expressed as a number from _________ to __________. pH meters are instruments

that measure the exact pH of a solution. Indicators register different colors at different pH’s. In

neutral solution, pH = 7. In an acidic solution, pH < 7. In a basic solution, pH > 7. As the pH

drops from 7, the solution becomes more acidic. As pH increases from 7, the solution becomes

more basic.

The pH of a solution equals the negative logarithm of the hydrogen ion concentration.pH = - log [H+]

Chemists have also defined a pOH scale to express the basicity of a solution. pOH = - log [OH-]

If either pH or pOH is known, the other may be determined by using the following relationship. pH + pOH = 14.00

Find the pH of the following solutions.

a) The hydronium ion concentration equals: 10–2 M. pH = _________________b) The hydronium ion concentration equals: 10–11 M. pH = _________________c) The hydronium ion concentration equals: 1 x 10–6 M. pH = _________________d) The hydroxide ion concentration equals: 10–8 M. pH = _________________e) The hydroxide ion concentration equals: 10–5 M. pH = _________________f) The hydroxide ion concentration equals: 10–3 M. pH = _________________

If a certain carbonated soft drink has a hydrogen ion concentration of 1.0 x 10–4 M, what are the pH and pOH of the soft drink?

173


Calculating Ion Concentrations From pHIf either pH or pOH is known, the hydrogen ion or hydroxide ion can be found.

[H+] =10-pH

[OH-] =10-pOH

On the calculator, hit 2nd log (-) and then the number.

Find the [H+] of a solution that has a pH equal to 6.



Find the [H+] of a solution that has a pOH equal to 6.




Find the [OH-] of a solution that has a pH equal to 10.

Calculating Ion Concentration From Ion ConcentrationIf either [H+] or [OH-] is known, the hydrogen ion or hydroxide ion can be found.

[H+] [OH-] = 1 x 10-14

Find the hydrogen ion concentration if the hydroxide ion concentration equals: 1 x 10–8 M.

Find the hydrogen ion concentration if the hydroxide ion concentration equals: 1 x 10–2 M.

Find the hydroxide ion concentration if the hydrogen ion concentration equals: 1 x 10–4 M.

Find the hydroxide ion concentration if the hydrogen ion concentration equals: 1 x 10–9 M.

IndicatorsChemical _____________________ whose colors are affected by acidic and basic solutions are

called indicators. Many indicators do not have a sharp color change as a function of

____________. Most indicators tend to be __________________ in more acidic solutions.

174


Which indicator is best to show an equivalence point pH of 4?



Neutralization ReactionsThe reaction of an acid and a base is called a neutralization reaction. Acid + base salt +

water A salt is an ___________________ compound.

Predict the products of and balance the following neutralization reactions. (Remember to check the oxidation numbers of the ions in the salt produced.)

a) HNO3 + KOH The salt is composed of the ________________ ion and the _________________ ion.

b) HCl + Mg(OH)2 c) H2SO4 + NaOH

Neutralization How many moles of HNO3 are needed to neutralize 0.86 moles of KOH?

How many moles of HCl are needed to neutralize 3.5 moles of Mg(OH)2?

How many moles of H3PO4 are needed to neutralize 3.5 moles of Mg(OH)2?

How many moles of HC2H3O2 are needed to neutralize 3.5 moles of Cr(OH)3?

175


If it takes 87 mL of an HCl solution to neutralize 0.67 moles of Mg(OH)2 what is the concentration of the HCl solution?

If it takes 58 mL of an H2SO4 solution to neutralize 0.34 moles of NaOH what is the concentration of the H2SO4 solution?

If it takes 85 mL of an HNO3 solution to neutralize 0.54 moles of Mg(OH)2 what is the concentration of the HNO3 solution?

If it takes 150. mL of an Ca(OH)2 solution to neutralize 0.800 moles of HCl what is the concentration of the Ca(OH)2 solution?

Acid RainAcid Rain is any rain with a pH less than __________. Pure rain is naturally acidic because of

dissolved _______________. It is caused by the man-made oxides of

_______________________ and nitrogen. SO3 + H2O è H2SO4 Research shows acid rain is

associated with parts of a country where heavy ______________________________ are situated

and also down-wind from such sites. Analysis of acid rain indicates that especially sulfur oxides,

SOx and nitrogen oxides, NOx are mostly responsible from rain acidity. Snow

_________________, sleet, hail and drizzle all become contaminated with acids when SOx and

NOx are present as pollutants.

TitrationThe known reactant molarity is used to find the unknown _________________________ of the

other solution. Solutions of known molarity that are used in this fashion are called

_________________________ solutions. In a titration, the molarity of one of the reactants, acid

or base, is known, but the other is unknown.

A 15.0-mL sample of a solution of H2SO4 with an unknown molarity is titrated with 32.4 mL of 0.145M NaOH to the bromothymol blue endpoint. Based upon this titration, what is the molarity of the sulfuric acid solution?

First find the number of moles of the solution for which you know the molarity and volume. Next, use the mole-mole ratio to determine the moles of the unknown. Finally, determine the molarity of the unknown solution.

If it takes 45 mL of a 1.0 M NaOH solution to neutralize 57 mL of HCl, what is the concentration of the HCl ?

If it takes 67.0 mL of 0.500 M H2SO4 to neutralize 15.0 mL of Al(OH)3 what was the concentration of the Al(OH)3 ?

176


How many moles of 0.275 M HCl will be needed to neutralize 25.0 mL of 0.154 M NaOH?

Titration Curves

A plot of ___________ versus volume of acid (or base) added is called a titration curve.Strong Base-Strong Acid Titration Curve

Consider adding a strong base (e.g. NaOH) to a solution of a strong acid (e.g. HCl). Before any

base is added, the pH is given by the strong _________________ solution. Therefore, pH ____

7. When base is added, before the equivalence point, the pH is given by the amount of strong

acid in _________________________. Therefore, pH < 7. At

________________________________ point, the amount of base added is stoichiometrically

equivalent to the amount of acid originally present. Therefore, pH =_________. To detect the

equivalent point, we use an indicator that changes ____________________somewhere near 7.00.

Past the equivalence point all acid has been consumed. Thus one need only account for excess

__________________. Therefore, pH ______ 7.

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Homework / PracticeShow all work for full credit.

1. Name the following compounds as acids.

a. H2SO4

b. H2SO3

c. H2S

d. HClO4

2. Write formulas for the following acids.

a. nitrous acid

b. hydrobromic acid

c. phosphoric acid

3. Use an activity series to identify two metals that will not generate hydrogen gas when treated with an acid.

4. Write balanced molecular equations for the reactions of acids and bases.

a. aluminum metal with dilute nitric acid

b. calcium hydroxide solution with acetic acid

5. Write the equation that represents the following reaction: the ionization of HClO3 in

water

6. Explain how strong acid solutions conduct an electric current.

7. CaCO3 (s) + HCl (aq) CaCl2 (aq) + H2O (l) + CO2 (g)

a. Balance the above equation.

b. How many liters of CO2 form at STP if 5.0 g of calcium carbonate are treated

with excess hydrochloric acid?

8. Consider the following reaction: NH4+ (aq) + CO3-2 (aq) ↔ NH3 (aq) + HCO3-1

(aq)

a. What reactant serves as the base?

b. What reactant serves as the acid?

9. Given the following reaction: HCO3-1 (aq) + OH-1 (aq) ↔ CO3-2 (aq) + H2O (l)

a. What reactant serves as the base?

178


b. What reactant serves as the acid?

10. Write the formula for the salt formed in each of the following neutralization reactions.

a. hydrobromic acid combined with barium hydroxide

b. lithium hydroxide combined with sulfuric acid

11. : H2SO4 (aq) + NaOH (aq) Na2SO4 (aq) + H2O (l)

a. Balance the above neutralization equation

b. In order to completely consume all reactants, what should be the mole ratio of acid to base?

12. Consider the reaction represented by the following incomplete equation:

Ba(OH)2 (aq) + H2SO4 (aq) a. Predict the products of this reaction, and write the balanced equation.

b. Use the solubility rules to determine the solubility of the salt produced in the reaction.

c. If 0.030 mol of Ba(OH)2 is consumed, how many grams of water are produced?

13. Name the acid that is present in vinegar.

14. Perform the following calculations.

a. If the hydronium concentration is 1 x 10-6 M for a solution, calculate the hydroxide concentration.

b. If the hydroxide concentration is 1 x 10-12 M for a solution, calculate the hydronium concentration.

c. If the pOH = 4.00 for a solution, calculate the pH. Is the solution acidic or basic?

d. If the hydronium concentration is 1.00 x 10-3M, calculate the pOH.

e. If the pOH = 5.0 for a solution, calculate the hydroxide concentration.

f. If the pH = 12.0 for a solution, calculate the hydronium concentration.

g. If the pH = 3.00 for a solution, calculate the hydroxide concentration.

h. If the hydronium concentration = 1.0 x 10-8 M for a solution, calculate the hydroxide concentration.

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15. Summarize the two main acid-base theories in the table below.

ACID BASE

Arrhenius

Brønsted-Lowry

16. Label the acid (A), base (B), conjugate acid (CA), and conjugate base (CB) in each of the following reactions.

a. H2SO4 + NH3 ® HSO4 + NH4

b. HC2H3O2 + H2O ® H3O+ + C2H3O2

c. NaHCO3 + HCl ® NaCl + H2CO3

17. Give the conjugate base for each of the following Brønsted-Lowry acids.

a. HI

b. NH4+

c. H2CO3

d. HNO3

18. Give the conjugate acid for each of the following Brønsted-Lowry bases.

a. CN–

b. O2–

c. CH3COO–

d. NH3

19. Find [OH] for 1.0 × 10-12M HClO4.

20. What is the pH of 1.0 × 10-4M HCl?

21. What is the pH of 1.5 × 10-3M NaOH?

22. A solution of HNO3 has a pH of 4.0. What is the molarity of HNO3?

23. What is the molarity of KOH in a solution that has a pH of 10.0?

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Acids and Bases Practice Test

Directions: Give the names or formulas for the following acids, bases, and salts:1. KOH________________________

2. HNO3 _______________________

3. Sulfuric Acid__________________

4. Magnesium hydroxide ___________

Directions:. 5. In complete sentences, define an acid according to the Arrhenius theory.

Directions: Label (according to Bronsted-Lowry) the Bronsted-Lowry acid, Bronsted-Lowry base, conjugate acid, and conjugate base in each of the equations below:

6. H₂O + HC2H3O2 ⇆ H₃O⁺ + C2H3O2⁻

7. CN-- + H₃O⁺ ⇆ H₂O + HCN

Directions Identify the following as an acid or a base, strong or weak. a.Acid or base b.Strong or weak

8. 2 M KOH __________ _____________

9. 7 M H₂SO₄ __________ _____________

10. 0.12 M H2S _________ _____________

Directions: Complete and balance the following neutralization reactions.

11. NaOH + HCl → _______________ + __________________

12. H₂SO₄ + KOH → _____________ + __________________

13. Determine the pOH for a solution of HNO3 that has a concentration of 0.01M.

14. Determine the pH for a solution of CuOH that has an [OH-] of 0.000001M.

Directions: Complete the following chart. [H₃O⁺]or

[H+]pH [OH⁻] pOH Acidic or

basic15. 1 x 10⁻6

16. 2

17. 4


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18. According to the Arrhenius theory, a base yieldsa. H+ as the only positive ion in an aqueous solutionb. OH+ as the only positive ion in an aqueous solutionc. OH- as the only negative ion in an aqueous solutiond. H- as the only negative ion in an aqueous solution

19. In the reaction H2SO4(aq) --> 2H+(aq) + SO4

-2(aq) H2SO4 is a(n)

a. Arrhenius acidb. Arrhenius base

c. Salt

20. Arrhenius acids yielda. OH- as the only negative ion in an aqueous solutionb. H- as the only negative ion in an aqueous solutionc. H3O+ as the only positive ion in an aqueous solutiond. OH+ as the only positive ion in an aqueous solution

21. Which of the following is an Arrhenius base?a. HClb. H2SO4

c. NaCld. NH3

22. Which of the following is a salt?a. HOHb. NH4NO3

c. HCld. H2CO3

23. A substance that conducts an electrical current when dissolved in water is calleda. an acidb. an electrolyte

c. an ionic compoundd. a nonelectrolyte

24. Which of the following can conduct an electric current?a. Mg(OH)2(s)b. H2O(s)

c. NaOH(aq)d. NH4Cl(s)

25. Which electrolyte is best at conducting electricity when dissolved in an aqueous solution?a. KCl(s)b. Na2SO4(s)

c. CaCl2(s)d. H3PO4(s)

26. A student dissolved NaCl(s) in water, and tested with a battery, wire, and a light blub to see if it conducted an electric current. The solution conducted an electric current. This is because NaCl(s) is

a. a salt and an electrolyteb. a salt and a nonelectrolytec. a Arrhenius acid and an electrolyted. a Arrhenius base and an electrolyte

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27. In the process of neutralization, an Arrhenius acid and an Arrhenius base react to form which of the following?

a. Water onlyb. Salt and Carbon dioxide

c. Water and Carbon dioxided. Water and Salt

28. What type of chemical reaction is neutralization?a. single replacementb. double replacement

c. synthesisd. decomposition

29. In the process of neutralization a salt and a base react to yield water and an acid.a. True b. False

30. Which of the following can be a product of neutralization?a. LiOH(s)

b. HCl(l)

c. MgI2(l)

d. NaCl(aq)

31. Which of the following reactants will represent a neutralization?a. BaCl2 + CaSO4

b. HCl + Fc. Ca(OH)2 + H2SO4

d. NaCl + H2O

32. When NaOH and HCl react, what will be on the product side?a. only NaClb. only HOH

c. NaCl and HOHd. NaCl and Cl2

33. A titration reaction involves a complete neutralization reaction where the moles of H+ equal the moles of OH-.

a. True b. False

34. Titration is a process in whicha. which a volume of solution of unknown concentration is used to determine the

concentration of another solution.b. which a volume of solution of known concentration is used to determine the

volume of another solution.c. which a volume of solution of known concentration is used to determine the

concentration of another solution.d. which a volume of solution of known concentration is used to determine the curve

of another solution.

35. In MaVa=MbVb, what is Mb?a. molarity of OH-

b. molarity of H+c. molarity of H-

d. molarity of O2

36. What is the molarity of HCl(aq) if 25 mL of 8.0M NaOH(aq) neutralizes exactly 20.0 mL of HCl(aq)?

a. 5M

b. 10Mc. 15M

d. 20M

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37. At the end point of titration, what is the relationship between moles of H+ and OH-?a. the moles of H+ are greater than OH-

b. the moles of OH- are greater than H+

c. the moles of H+ are equal to moles of OH-

d. there is no relationship between moles of H+ and OH-

38. The molarity of HBr(aq) is 2M when 10 milliliters of 8M NaOH(aq) neutralizes exactly 20 milliliters of HBr.

a. True b. False

39. What is the molarity of NaOH if 5. milliliters of 4M HCl(aq) neutralizes exactly 10. mL of NaOH(aq)?

a. .5Mb. 1M

c. 1.5Md. 2M

40. If 10.milliliters of a 0.40M HBr solution is required to neutralize exactly 0.2M of NaOH, what is the volume of the base?

a. 10mlb. 20ml

c. 30mld. 40ml

41. The molarity of an acid can be calculated if a base of known concentration (standard base) is added, drop by drop, to a specific volume of the acid until the indicator changes color.

a. True b. False

42. One acid-base theory states that an acid is an H+

a. Acceptorb. Eliminator

c. Dissolverd. Donor

43. According to the Bronsted-Lowry acid-base theory, a base is a substance that cana. donate an electronb. accept a proton

c. donate a protond. accept a electron

44. In the following reaction, NH3 + HCl --> NH4+ + Cl- NH3 acts as a(n)

a. base in the reverse reaction.b. acid in the forward reaction.

c. base in the forward reaction.d. acid in the reverse reaction.

45. The acidity or alkalinity of a solution can be measured by its pH value.a. True b. False

46. The relative level of acidity or alkalinity of a solution can be shown by using their pH values.

a. True b. False

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47. Which of these 1 M solutions will have the highest pH?a. H3PO4

b. HClc. NaCld. NaOH

48. Which pH indicates an acidic solution?a. 1 b. 7 c. 9 d. 12

49. Which of these pH numbers indicates the lowest level of acidity?a. 1 b. 3 c. 8 d. 12

50. Which formula represents a salt?a. KOH b. KCl

c. CH3OH d. CH3COOH

51. Which substance can be classified as an Arrhenius acid?a. HCl b. NaCl

c. LiOH d. KOH

52. Which solution will change red litmus to blue?a. HCl(aq) b. NaCl(aq)

c. CH3OH(aq) d. NaOH(aq)

53. An acidic solution could have a pH ofa. 7 b. 10 c. 3 d. 14

54. What is the pH of a 0.00001 molar HCl solution?a. 1 b. 9 c. 5 d. 4

55. What is the pH of a solution with a hydronium ion concentration of 0.01 moles per liter?a. 1 b. 2 c. 10 d. 14

56. Which 0.1 M solution will turn phenolphthalein pink?a. HBr(aq) b. CO2(aq)

c. LiOH(aq) d. CH3OH(aq)

57. Given the equation: H+ + OH- <-> H2OWhich type of reaction does the equation represent?

a. esterification b. decomposition

c. hydrolysis d. neutralization

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58. As the hydrogen ion concentration of an aqueous solution increases, the hydroxide ion concentration of this solution will

a. decrease b. increase

c. remain the same

59. A student wishes to prepare approximately 100 milliliters of an aqueous solution of 6M HCl using 12 M HCl. Which procedure is correct?

a. adding 50 mL of 12 M HCl to 50 mL of water while stirring the mixture steadily. b. adding 50 mL of 12 M HCl to 50 mL of water and then stirring the mixture

steadily. c. adding 50 mL of water to 50 mL of 12 M HCl while stirring the mixture steadily. d. adding 50 mL of water to 50 mL of 12 M HCl and then stirring the mixture

steadily. 60. The reaction of an acid like HCl and a base like NaOH always

a. Forms a precipitateb. Forms a volatile product

c. Forms a salt and waterd. Forms a sulfate and water

61. What is the pH of an acetic acid solution if the [H3O+] = 1x10-4 mol/L?a. 1b. 2

c. 3d. 4

e. 5

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Unit 12- Kinetics and Thermochemistry

REACTION KINETICS

Energy Diagrams

Reactants always start a reaction so they are on the _________________ side of the diagram.

Products are on the right. The exothermic reaction gives off ___________________ because the

products are at a lower energy level than the reactants. In an exothermic graph, the reactants

have _____________________ energy than the products. The change in energy is a

_________________________ value.

The endothermic reaction absorbs heat because the products are at a

_________________________ energy level than the reactants. In an endothermic graph, the

products have _____________________ energy than the reactants. The change in energy is a

_______________________ value.

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Scientists have observed that the energy released in the formation of a compound from its

elements is always identical to the energy required to ______________________ that compound

into its elements.

_____________________________ energy is the minimum amount of energy that reacting

particles must have to form the activated complex. The activated complex is a short-lived,

_________________ arrangement of atoms that may break apart and re-form the reactants or

may form products. To calculate the activation energy, ______________________ the energy of

the reactants from the energy at the top of the peak. The enthalpy or heat of reaction (ΔH) is the

amount of ___________________ released or absorbed in the reaction. To determine ΔH, take

the energy of the products and _______________________ the energy of the reactants.

The heat content of the reactants of the forward reaction is about ________ kilojoules.

189


The heat content of the products of the forward reaction is about ________ kilojoules.

The heat content of the activated complex of the forward reaction is about _______

kilojoules.

The activation energy of the forward reaction is about _______ kilojoules.

The heat of reaction (ΔH) of the forward reaction is about _______ kilojoules.

The forward reaction is (endothermic or exothermic).

The heat content of the reactants of the reverse reaction is about ________ kilojoules.

The heat content of the products of the reverse reaction is about ________ kilojoules.

The heat content of the activated complex of the reverse reaction is about _______

kilojoules.

The activation energy of the reverse reaction is about _______ kilojoules.

The heat of reaction (ΔH) of the reverse reaction is about _______ kilojoules.

The reverse reaction is (endothermic or exothermic).

The activation energy can be lowered by adding a __________________________. The catalyst

_________________ the activation energy by providing an alternate pathway for the reaction to

occur.

Expressing Reaction Rates

We generally define the average _____________________ of an action or process to be the

change in a given quantity during a specific period of time. Reaction rates cannot be calculated

from balanced equations as stoichiometric amounts can. Reaction rates are determined

experimentally by measuring the _____________________________ of reactants and/or

products in an actual chemical reaction.

Collision Theory

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According to the collision theory, atoms, ions, and molecules must collide with each other in

order to react. The following three statements summarize the collision theory.

1. Particles must ________________________ in order to react.

2. The particles must collide with the correct _______________________________.

3. The particles must collide with enough ________________________ to form an

unstable activated complex, also called a _____________________________ state,

which is an intermediate particle made up of the joined reactants.

The _____________________________ amount of energy that colliding particles must have in

order to form an activated complex is called the activation energy of the reaction. Particles that

collide with energy less than the activation energy ____________________________ form an

activated complex. In an exothermic reaction, molecules collide with enough energy to

overcome the activation energy barrier, form an activated complex, then

__________________________ energy and form products at a lower energy level. In the

reverse endothermic reaction, the reactant molecules lying at a _______________ energy level

must absorb energy to overcome the activation energy barrier and form high-energy products.

Factors Affecting Reaction Rates

The reaction rate for almost any chemical reaction can be modified by varying the conditions of

the reaction.

1) An important factor that affects the rate of a chemical reaction is the reactive nature of

the reactants. As you know, some substances react more readily than others. The more

reactive a substance is, the _____________________________ the reaction rate.

2) Another important factor that affects the rate of a chemical reaction is the concentration

of the reactants. Reactions ______________________ _________________ when the

concentrations of reacting particles are increased. Increasing the number of reactants

increases probability of collisions. The rate of gaseous reactions can be ___________ by

pumping more gas into the reaction container.

3) Surface area of the reactants affects the rate of a chemical reaction.

______________________ the surface area of reactants provides more opportunity for

collisions with other reactants, thereby increasing the reaction rate.

191


4) Temperature affects the rate of a chemical reaction. Generally, increasing the

temperature at which a reaction occurs _________________________ the reaction rate.

Raising the temperature raises both the collision frequency and the collision energy.

5) Adding a catalyst affects the rate of a chemical reaction. A catalyst is a substance that

increases the rate of a chemical reaction without itself being consumed in the reaction. In

fact, catalysts are not included in the chemical equation.

6) Compressing gases affects the rate of a chemical reaction. When two gases react,

compressing the gases generally ___________ the rate of reaction.

REACTION ENERGY

Energy is the ability to do___________________ or produce heat. It exists in two basic forms,

potential energy and ______________________ energy. Potential energy is energy due to the

______________________ or position of an object. Kinetic energy is energy of

________________. The potential energy of the dammed water is converted to kinetic energy as

the dam gates are opened and the water flows out. Chemical systems contain

_________________ kinetic energy and potential energy. As temperature increases, the motion

of submicroscopic particles ______________________, so its kinetic energy

__________________________. The potential energy of a substance depends upon its

composition: the type of atoms in the substance, the number and type of chemical bonds joining

the atoms, and the particular way the atoms are arranged.

Law of Conservation of Energy and Heat

The law of conservation of energy states that in any chemical reaction or physical process,

energy can be converted from one form to another, but it is neither created nor

________________________.

Heat, which is represented by the symbol ____, is energy that is in the process of flowing from a

_____________________ object to a cooler object. The SI unit of heat and energy is the joule

(J). Heat involves a transfer of energy between 2 objects due to a ________________________

192


difference. When the warmer object loses heat, its temperature decreases and q is

_________________________. When the cooler object absorbs heat, its temperature

________________ and q is positive.

The specific heat of any substance is the amount of heat required to raise the temperature of ____

gram of that substance by one degree Celsius. Because different substances have different

compositions, each substance has its own specific heat.

q = m Cp ∆Tq = heat (J); m = mass (g); Cp = specific heat (J/(g.°C); ∆T = change in temperature = Tf – Ti

(°C)

Exothermic: Heat flows _________ of the system (to the surroundings). The value of ‘q’ is

negative. Endothermic: Heat flows _________ the system (from the surroundings). The value

of ‘q’ is positive.

The temperature of a sample of iron with a mass of 10.0 g changed from 50.4°C to 25.0°C with the release of 114 J heat. What is the specific heat of iron?

A piece of metal absorbs 256 J of heat when its temperature increases by 182°C. If the specific heat of the metal is 0.301 J/g.°C, determine the mass of the metal.

If 335 g water at 65.5°C loses 9750 J of heat, what is the final temperature of the water? The specific heat of water is 4.18 J/g.°C.

As 335 g of aluminum at 65.5°C gains heat, its final temperature is 300.°C. The specific heat of aluminum is 0.897 J/g.°C. Determine the energy gained by the aluminum.

Heat changes that occur during chemical and physical processes can be measured accurately and

precisely using a ___________________________. A calorimeter is an insulated device used

for measuring the amount of heat absorbed or released during a chemical or physical process. A

coffee-cup calorimeter made of ________ Styrofoam cups.

Suppose you put 125 g of water into a foam-cup calorimeter and find that its initial temperature is 25.6°C. Then, you heat a 50.0 g sample of the unknown metal to a temperature of 115.0°C and put the metal sample into the water. Both water and metal have attained a final temperature of 29.3°C. Heat flows from the hot metal to the cooler water and the temperature of the water rises. The flow of heat stops only when the temperature of the metal and the water is equal. Assuming no heat is lost to the surroundings, the heat gained by the water is equal to the heat lost by the metal. Determine the specific heat of the metal.

You put 352 g of water into a foam-cup calorimeter and find that its initial temperature is 22.0°C. What mass of 134°C lead, Clead = 0.129 J/g°C, can be placed in the water so that the equilibrium temperature is 26.5°C?

193


You put water into a foam-cup calorimeter and find that its initial temperature is 25.0°C. What is the mass of the water if 14.0 grams of 125°C nickel, CNi = 0.444 J/g°C, can be placed in the water so that the equilibrium temperature is 27.5°C?

Phase Changes Review

Solid → liquid ________________________ Liquid → solid ___________________

Liquid → gas ________________________ Gas → liquid _____________________

Solid → gas ________________________ Gas → solid ______________________

Energy and Phase Changes

q = m Hf q = m Hv

Hf = latent heat of fusion (J/g) ; Hv = latent heat of vaporization (J/g)

Water

Waterand IceIce

Water and Steam

Steam

-20

0

20

40

60

80

100

120

0 40 120 220 760 800

Heating Curve for Water

Water

Waterand IceIce

Water and Steam

Steam

-20

0

20

40

60

80

100

120

0 40 120 220 760 800

Heating Curve for Water

Heat of vaporization (Hv) is the energy required to change one gram of a substance from

________________ to gas. Heat of fusion (Hf) is the energy required to change one gram of a

substance from __________________ to liquid.

How much heat does it take to melt 12.0 g of ice at 0 °C? Hf for water is 334 J/g.

How much heat must be removed to condense 5.00 g of steam at 100 °C? Hv = 2260 J/g.

Three equations can be used in calculating energy.

q = m Cp ΔT q = m Hf q = m Hv

Solving Problems

The total heat equals the sum of all the heats you have to use.

Go in the following order when energy is being added to the system.

1) Heat ice q = m Cice ∆T 2) Melt ice q = m Hf

3) Heat water q = m Cwater ∆T 4) Boil water q = m Hv

194

The heating curve has _____ distinct

regions. The ______________________

lines are where phase changes occur.

Temperature is ___________________

during a phase change!


5) Heat steam q = m Csteam ∆T

Numbers Needed For Energy Problems Involving Water (look up in reference tables)

For ice, specific heat = __________ For water, specific heat = _________For steam, specific heat = _____________ Heat of vaporization = ___________Heat of fusion = _____________

How much heat does it take to heat 12 g of ice at – 6 °C to 25 °C water? Round to a whole number.

How much heat does it take to heat 35 g of ice at 0 °C to steam at 150 °C? Round to a whole number.

How much heat does it take to convert 16.0 g of ice to water at 0 °C?

How much heat does it take to heat 21.0 g of water at 12.0°C to water at 75.0°C?

How much heat does it take to heat 14.0 g of water at 12.0°C to steam at 122.0°C?

Entropy

Entropy (S) is a measure of the ______________________ or randomness of the particles that

make up a system. Spontaneous processes always result in a(n) _____________________ in the

entropy of the universe. Entropy of a solid < Entropy of a liquid << Entropy of a gas A solid

has an orderly arrangement. A liquid has the molecules next to each other. A gas has molecules

moving all over the place.

Several factors affect the change in entropy of a system.

1. Changes of state. Entropy ___________________ when a solid changes to a liquid and

when a liquid changes to a gas because these changes of state result in freer movement of

the particles.

2. Dissolving of a gas in a solvent. When a gas is dissolved in a liquid or solid solvent, the

motion and randomness of the particles are limited and the entropy of the gas

_____________.

3. Change in the number of gaseous particles. When the number of gaseous particles

increases, the entropy of the system usually ___________________ because more

random arrangements are possible.

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4. Dissolving of a solid or liquid to form a solution. When solute particles become

dispersed in a solvent, the disorder of the particles and the entropy of the system usually

________________.

5. Change in temperature. A temperature increase results in increased disorder of the

particles and a(n) ____________________ in entropy.

Predict the sign of ∆Ssystem for: O2 (g) O2 (aq)

Predict the sign of ∆Ssystem for: C6H6 (s) C6H6 (l)

Predict the sign of ∆Ssystem for: C (s) + CO2 (g) 2 CO (g)

Homework / Practice

1. If 200. g of water at 20.0 °C absorbs 41840 J of heat, what will its final temperature be?

2. Aluminum has a specific heat of 0.900 J/g.°C. How much energy is needed to raise the temperature of a 625 g block of aluminum from 30.7 °C to 82.1 °C?

3. The products in a reaction have a total heat content of 458 kJ and the reactants have a total heat content of 656 kJ. What is the value of ∆H?

4. If a reaction is exothermic, are the products or the reactants more stable?

5. The heat of combustion of ethene gas, C2H2, is - 1301.1 kJ/mol of ethene.

(a) If 0.250 mol of ethene react, how much energy is released?

(b) How many grams of ethene are needed to react to release 3900. kJ of heat?

(c) Write a balanced reaction for the combustion of ethene.

6. For each of the following examples, state whether the change in entropy is positive, negative or remains the same.

196


(a) HCl (l) → HCl (g)

(b) C6H12O6 (aq) → C6H12O6 (s)

(c) 2 NH3 (g) → N2 (g) + 3 H2 (g)

(d) 3 C2H4 (g) → C6H12 (l)

7. List 4 factors that can speed up a chemical reaction.

8. Sketch on the graph above the changes when a catalyst is added.

9. Consider the following equilibrium equation: H2O (g) + C (s) → H2 (g) + CO (g) +

heat energy. Will the reaction rate increase or decrease when each of the following occurs?

(a) extra CO gas is introduced

(b) a catalyst is introduced

(c) the temperature of the system is lowered

(d) the pressure of the system is increased

10. Convert from one unit to the other:

(a) 1.69 Joules to calories(b) 0.3587 J to cal(c) 820.1 J to kilocalories(d) 68 calories to kilocalories(e) 423 calories to kilocalories(f) 20.0 calories to Joules(g) 252 cal to J(h) 2.45 kilocalories to calories

(i) 556 kilocalories to cal(j) 6.78 kilocalories to kilojoules(k) 59.6 calories to kcal(l) 449.6 joules to kilojoules(m) 9.806 kJ to J(n) 5.567 cal to J(o) 5467.9 kcal to J

11. How much energy must be absorbed by 20.0 g of water to increase its temperature from 283.0 °C to 303.0 °C?

197


12. When 15.0 g of steam drops in temperature from 275.0 °C to 250.0 °C, how much heat energy is released?

13. How much energy is required to heat 120.0 g of water from 2.0 °C to 24.0 °C?

14. If 720.0 g of steam at 400.0 °C absorbs 800.0 kJ of heat energy, what will be its increase in temperature?

15. How much heat (in kJ) is given out when 85.0 g of lead cools from 200.0 °C to 10.0 °C? (Cp of lead = 0.129 J/g °C)

16. If it takes 41.72 joules to heat a piece of gold weighing 18.69 g from 10.0 °C to 27.0 °C, what is the specific heat of the gold?

17. A certain mass of water was heated with 41,840 Joules, raising its temperature from 22.0 °C to 28.5 °C. Find the mass of water.

18. Determine the energy required (in Joules) when the temperature of 3.21 grams of liquid water increases by 4.0 °C.

19. Determine the temperature change when: (a) 20.0 g of water is heated from 16.8 °C to 39.2 °C.(b) 35.0 g of water is cooled from 56.5 °C to 5.9 °C.(c) 50.0 g liquid water is heated from 0.0 °C to 100.0 °C.(d) 25.0 g of ice is warmed from -25.0 °C to 0.0 °C, but does not melt.(e) 30.0 g of steam heats from 373.2 K to 405.0 K.

198


20. Determine the energy needed (in Joules) when 55.6 grams of water at 43.2 °C is heated to 78.1°C.

21. Determine the energy required (in kilojoules) when cooling 456.2 grams of water at 89.2 °C to a final temperature of 5.9 °C.

22. Determine the energy required to: (a) melt 5.62 moles of ice at 0 °C.(b) melt 74.5 grams of ice at 0 °C.(c) boil 0.345 moles of water at 100.0 °C.(d) boil 43.89 grams of water at 100.0 °C. (e) Convert 16.2 grams of ice to liquid water.(f) Convert 5.8 grams of water to steam(g) Convert 98.2 grams of water to ice.(h) Convert 52.6 grams of steam to water(i) Convert 34.0 grams of water at 20.0 °C to steam at 100.0 °C.(j) Convert 125.0 grams of ice at 0.0 °C to steam at 100.0 °C.(k) Convert 25.9 grams of steam at 100.0 °C.to ice at 0.0 °C.

23. Determine the specific heat of a 150.0 gram object that requires 62.0 cal of energy to raise its temperature 12.0 °C.

24. Determine the energy required to raise the temperature of 46.2 grams of aluminum from 35.8 °C to 78.1 °C. Specific heat capacity of aluminum is 0.089 J/g °C.

25. How many degrees of temperature rise will occur when a 25.0-g block of aluminum absorbs 10.0 kJ of heat? The specific heat of aluminum is 0.897 J/g·°C.

Kinetics and Thermochemistry Practice Test

Directions: Match the terms below with their correct definitions. (1-4)

a. calorimete

r

b. thermoche

mistry

c. enthalpy

199


d. system

1. The study of heat changes that accompany chemical reactions and phase changes

2. The specific part of the universe that contains the reaction or process you wish to

study

3. The heat content of a system at constant pressure

4. An insulated device used to measure the amount of heat absorbed or released during a

chemical or physical process

5. Predict the change in entropy (ΔS) for the following reaction (will it increase, decrease,

or stay the same).CH4(g) + 2O2(g) 2H2O(l) + CO2(g)

6. Which of the following species has the highest entropy at 25°C? Explain your answer.

a) CH3OH(l)

b) CO(g)

c) MgCO3(s)

d) H2O(l)

e) Ni(s)

Directions: Solve the following problems, show all of your work7. If the temperature of a 25-g sample of liquid water is raised 40°C, how much heat is

absorbed by the water?

8. Copper metal has a specific heat of 0.385 J/g·°C , calculate the amount of heat required to raise the temperature of 38 g of copper from 20.0°C to 575°C.

9. When a 50.0-g nugget of pure gold is heated from 35.0°C to 50.0°C, it absorbed 5200.0 J of energy. Find the specific heat of gold.

10. When 80.0 grams of a certain metal at 90.0 °C was mixed with 100.0 grams of water at 30.0 °C, the final equilibrium temperature of the mixture was 36.0 °C. What is the specific heat of the metal?

200


Directions: Use the energy diagram for the

rearrangement reaction of methyl isonitrile to

acetonitrile to answer the following questions. (11-

13)

11. What kind of reaction is represented by this diagram, endothermic or exothermic?

12. What does the symbol E represent?

13. How does a catalyst speed a reaction?


14. As ice cools from 273 K to 263 K, the average kinetic energy of its molecules willa) decrease b) increase

c) remain the same

15. The heat of fusion is defined as the energy required at constant temperature to change 1 unit mass of a

a) gas to a liquid b) gas to a solid

c) solid to a gas d) solid to a liquid

16. What is the total number of joules of heat energy absorbed by 15 grams of water when it is heated from 30°C to 40°C?

a) 10 b) 63

c) 150 d) 630

17. How many joules of heat are absorbed when 70.0 grams of water is completely vaporized at its boiling point?

a) 23, 352 b) 7, 000

c) 15, 813 d) 158, 130

201


18. What occurs as potassium nitrate is dissolved in a beaker of water, indicating that the process is endothermic?

a) The temperature of the solution decreases. b) The temperature of the solution increases. c) The solution changes color. d) The solution gives off a gas.

19. A solid is dissolved in a beaker of water. Which observation suggests that the process is endothermic?

a) The solution gives off a gas. b) The solution changes color. c) The temperature of the solution decreases. d) The temperature of the solution increases.

20. When a catalyst is added to a system at equilibrium, a decrease occurs in thea) activation energy b) heat of reaction c) potential energy of the reactants d) potential energy of the products

21. Which statement explains why the speed of some chemical reactions is increased when the surface area of the reactant is increased?

a) This change increases the density of the reactant particles. b) This change increases the concentration of the reactant. c) This change exposes more reactant particles to a possible collision. d) This change alters the electrical conductivity of the reactant particles.

22. Which conditions will increase the rate of chemical reaction?a) decreased temperature and decreased concentration of reactants? b) decreased temperature and increased concentration of reactants? c) increased temperature and decreased concentration of reactants? d) increased temperature and increased concentration of reactants?

23. In a chemical reaction, a catalyst changes thea) potential energy of the products b) potential energy of the reactants c) heat of reaction d) activation energy

202


24. Given the change of phase: CO2(g) changes to CO2(s), the entropy of the systema) decreases b) increases

c) remains the same

25. The following reaction coordinate diagram represents...

a) an endothermic reactionb) an exothermic reactionc) a reaction that is neither

endothermic nor exothermic

d) a reaction in which a catalyst is used

26. If 1.45 J of heat are added to a 2.00 g sample of aluminum metal and the temperature of the metal increases by 0.798 oC, what is the specific heat of aluminum?

a) 0.579 J/g deg b) 0.909 J/g deg

c) 1.68 J/g deg d) 3.63 J/g deg

27. Water has a specific heat of 4.184 J/g deg while glass (Pyrex) has a specific heat of 0.780 J/g deg. If 10.0 J of heat is added to 1.00 g of each of these, which will experience the larger increase of temperature?

a) glass b) water c) They both will experience the same change in temperature since only the

amount of a substance relates to the increase in temperature.

28. How many PopTarts® are needed to convert 1,000.0 g of water at 20.0 oC to steam at 100.0 oC? One PopTart is equal to 800,000 J of energy...wow!

a) 0.419 PopTart b) 2.83 PopTarts

c) 3.25 PopTarts

29. The collision theory states that a reaction is most likely to occur if reactant particles collide with the proper

a) energy and concentrationb) energy and orientationc) concentration and orientationd) pressure and orientation

30. What will happen to the rate of reaction when temperature increases?a) Increaseb) Decreasec) remains the same

d) increase then decrease

203


31. Given the following reaction H+(aq) + OH-

(aq) --> H2O(l) if the concentration of the reactants is increased, the rate of reaction will

a) Increaseb) Decreasec) remains the same

d) increase then decrease

32. What does a catalyst decrease when introduced to a reaction?a) the rate of reactionb) the energy released

during the reaction

c) the activation energy

d) the kinetic energy

33. Catalysts increase the rate of reaction by being consumed.a) True b) False

34. Entropy is a measure of the randomness or disorder of a system.a) True b) False

35. Systems in nature tend to undergo changes toward what kind of energy and entropy?a) lower energy and lower entropyb) lower energy and higher entropyc) higher energy and higher entropyd) higher energy and lower entropy

36. Which process is accompanied by a increase in entropy?a) melting of iceb) freezing of water

c) condensing of water vapor

37. What phase change represents a decrease in entropy?a) solid to liquidb) liquid to gas

c) gas to liquidd) solid to gas

38. H2O(g)--> H2O(l) The entropy in this equationa) Increasesb) Decreases

c) remains the same

39. Which sample has the lowest entropy?a) 1 mole of KNO3(l)

b) 1 mole of KNO3(g)

c) 1 mole of H2O(g)

d) 1 mole of KNO3(s)

204


40. In a chemical reaction, if the products have more entropy than the reactants, the change in entropy is negative.

a) True b) False

41. What is the change in entropy in the following reaction C + O2 -> CO2

a) Increasesb) Decreasesc) remains the samed) not enough information to tell

42. What is the change in entropy in the following reaction 4Al(s) + 3O2(g) -> 2Al2O3(s)

a) Increaseb) Decreasec) remains the samed) not enough information to tell

43. What is the change in entropy in the following reaction N2(g) + O2(g) -> 2NO(g)

a) Increaseb) Decreasec) remains the samed) not enough information to tell

44. A 47.5 gram sample of a metal at a temperature of 425°C is placed in 1.00 liters (1000 g) of water which had an initial temperature of 18°C. What is the specific heat capacity of the metal if the final temperature of the metal and water at equilibrium is 21°C? (The specific heat capacity of water is 4.18 J/°C·g.

a) 0.03 J/°C·g b) 1.47 J/°C·g c) -0.75 J/°C·g

d) 0.65 J/°C·g e) 12.54 J/°C·g

45. A bomb calorimeter has a heat capacity of 3.18 kJ/K. When 0.0038 mol of a gas is burned in the calorimeter, the temperature increased from 25.0°C to 27.3°C. Calculate the energy released by the combustion of one mole of the gas.

a) 2.8 x 10-2 kJ b) 7.3 kJ c) -1.9 x 103 kJ

d) -2.8 x 10-2 kJ e) -3.6 x 102 kJ

46. A sample of wood has a heat of combustion of 3.29 kJ/g. What quantity of the wood must be burned to heat 250. g of water from 18°C to 85°C? Once again, the specific heat capacity of water is 4.18 J/°C·g.

a) 85.1 g b) 0.45 g

c) 12.4 g d) 2.13 x 104 g

205


e) 21.3 g47. 20.0 mL of pure water at 285 K is mixed with 48 mL of water at 315 K. What is the

final temperature of the mixture in kelvins?a) 306 K b) 290 K c) 318 K

d) None of thesee) 275 K

48. The specific heat of liquid water is 4.18 J/°C·g and the specific heat of carbon is 0.71J/°C·g. A 10 gram sample of water and a 10 gram sample of carbon are each subjected to 155 J of heat. If both samples started at 25°C, which substance will have the higher final temperature, and by what magnitude?

a) Neither. They will have the same final temperature because the started at the same temperature and were exposed to the same quantity of heat.

b) carbon, by 18.1°C c) water, by 3.47°C d) carbon, by 215°C e) water, by 28.7°C

49. As a result of an exothermic reaction,a) the energy of the system is increased and the energy of the surroundings

are decreased. b) the energy of the system and the energy of the surroundings are

decreased. c) the energy of the system is decreased and the energy of the surroundings

are increased. d) the energy of the system and the energy of the surroundings are

increased. e) None of these are accurate

50. The specific heat of iron is 0.450 J/(g·°C). How much heat is required to raise the temperature of a 5.00 gram sample of iron from 22°C to 53°C?

a) -43 J b) 155 J c) 344 J

d) 18 Je) 69.8 J

51. How much energy is needed to convert 50.0 g of ice at -5.00°C to water at 25°C?a) 22.4 kJ b) 37.3 kJ

206


c) 21.9 kJ

d) 18.0 J

e) 175 J

52. Which of the following is not an endothermic process?a) combustionb) melting c) crystallization

d) vaporization e) sublimation

53. Increasing the temperature at which a reaction occurs speeds up the reaction by:a) improving the orientation of collisions b) increasing the energy of collisions c) activating catalysts d) increasing the frequency of collisions e) two of these

54. For which of the following processes would ΔS° be expected to be most positive?a) CO2(g) → CO2(s) b) C6H12O6(s) + 6 O2(g) → 6 CO2(g) + 6 H20(g) c) H+(aq) + OH-(aq) → H2O(l) d) Cl2(g) + H2(g) → 2 HCl(g)e) Na+(aq) + Cl-(aq) → NaCl(s)

207

Unit 13- Oxidation and Reduction

OXIDATION-REDUCTION

One of the defining characteristics of single-replacement and combustion reactions is that they

always involve the transfer of ____________________________________ from one atom to

another. So do many, but not all, synthesis and decomposition reactions. The

________________________________ number of an atom in an ionic compound is the number

of electrons lost or gained by the atom when it forms ions. Oxidation numbers are tools that

scientists use in written chemical equations to help them keep track of the movement of electrons

in a ________________________ reaction. Like some of the other tools you have learned about

in chemistry, oxidation numbers have a specific notation. Oxidation numbers are written with

the positive or negative sign __________________________ the number (+3, +2), whereas ionic

charge is written with the sign after the number (3+, 2+). Oxidation number: +3. Ionic charge:

3+. In order to understand all kinds of redox reactions, you must have a way to determine the

oxidation number of the atoms involved in the reaction. Chemists use a set of rules to make this

determination easier.

1. The oxidation number of an uncombined atom is _______________________. This is

true for elements that exist as polyatomic molecules such as O2, Cl2, H2, N2, S8.

2. The oxidation number of a _____________________ ion is equal to the charge on the

ion. For example, the oxidation number of a Ca2+ ion is +2, and the oxidation number of

a Br– ion is –1.

3. The oxidation number of the _______________________ electronegative atom in a

molecule or a complex ion is the same as the charge it would have if it were an ion.

• In ammonia (NH3), for example, nitrogen is more electronegative than hydrogen,

meaning that it attracts electrons more strongly than does hydrogen. So nitrogen

is assigned an oxidation number of –3, as if it had gained three electrons to

complete an octet. In the compound silicon tetrachloride (SiCl4), chlorine is more

electronegative than silicon, so each chlorine has an oxidation number of –1 as if

it had taken an electron from silicon. The silicon atom is given an oxidation

number of +4 as if it had lost electrons to the four chlorine atoms.


4. The most electronegative element, _________________________________, always has

an oxidation number of –1 when it is bonded to another element.

5. The oxidation number of oxygen in compounds is always ___________, except in

peroxides, such as hydrogen peroxide (H2O2), where it is –1. When it is bonded to

fluorine, the only element more electronegative than oxygen, the oxidation number of

oxygen is +2.

6. The oxidation number of hydrogen in most of its compounds is _____________. The

exception to this rule occurs when hydrogen is bonded to less electronegative metals to

form _______________________ such as LiH, NaH, CaH2, and AlH3. In these

compounds, hydrogen’s oxidation number is –1 because it attracts electrons more

strongly than does the metal atom.

7. The metals of groups 1A and 2A and aluminum in group 3A form compounds in which

the metal atom always has a ___________________________ oxidation number equal to

the number of its valence electrons (+1, +2, and +3, respectively).

8. The sum of the oxidation numbers in a neutral compound is ______________________.

9. The sum of the oxidation numbers of the atoms in a

________________________________ ion is equal to the charge on the ion.

Determining Oxidation Numbers

Determine the oxidation number of each element in the following compounds or ions. Assign

the known oxidation numbers to their elements, set the sum of all oxidation numbers to zero or to

the ion charge, and solve for the unknown oxidation number. (Let nelement = oxidation number of

the element in question.)

• KClO3 (potassium chlorate) Potassium chlorate is a _________________________ salt,

so oxidation numbers must add up to zero. K’s oxid. # + Cl’s oxid. # + 3 (O’s oxid. #)

= 0 Rule _________ states that Group 1 metals have a +1 oxidation number in

compounds. According to rule ___________, the oxidation number of oxygen in

compounds is –2. (+1) + (nCl) + 3 (-2) = 0. Chlorine’s oxidation number

must equal _______.

• SO32– (sulfite ion) Sulfite ion has a charge of 2–, so oxidation numbers must add up to

______. S’s oxid. # + 3 (O’s oxid. #) = –2. According to rule 5, the oxidation number


of oxygen in compounds is –2. (nsulfur) + 3 (-2) = –2. Sulfur’s oxidation number must

equal _______.

• Determine the oxidation number of each element in the following compound or ion.

a) Na2CO3 ___________________________________________

b) H2SO4 ___________________________________________

c) Mg3P2 ___________________________________________

d) SrH2 ___________________________________________

e) PO4-3 ___________________________________________

f) ClO4-1 ___________________________________________

g) C4H10 ___________________________________________

Electron Transfer and Redox Reactions

Complete Chemical Equation: 2 Na (s) + Cl2 (g) 2 NaCl (s)

Net Ionic Equation: 2 Na (s) + Cl2 (g) 2 Na+ + 2 Cl-

• Solid sodium, on the reactant side, has an oxidation number of _______. The sodium ion

product has an oxidation number of _______.

Oxidation is defined as the ____________________ of electrons from atoms of a substance.

When an element’s oxidation number ________________________, the element is said to be

oxidized.

• Sodium’s oxidation number changes from 0 to +1. Sodium is oxidized because it loses

______ electron. To state this reaction more clearly, Na → Na+ + e-. For oxidation to

take place, the electrons lost by the substance that is oxidized must be accepted by atoms

or ions of another substance. In other words, there must be an accompanying process that

involves the ________________ of electrons.

_____________________________ is defined as the gain of electrons by atoms of a substance.

Net Ionic Equation: 2 Na (s) + Cl2 (g) 2 Na+ + 2 Cl-

• Chlorine gas, on the reactant side, has an oxidation number of _______. The chlorine ion

product has an oxidation number of _______. Chlorine’s oxidation number changes from

0 to -1. Chlorine is reduced because it _________________ one electron. Following

our sodium chloride example further, the reduction reaction that accompanies the

oxidation of sodium is the reduction of chlorine. Cl2 + 2 e- → 2 Cl-. In this reaction,


an electron from each of two sodium atoms is transferred to the Cl2 molecule to form two

Cl– ions.

Complete Chemical Equation: 2 Mg (s) + O2 (g) 2 MgO (s)

Net Ionic Equation: 2 Mg (s) + O2 (g) 2 Mg2+ + 2 O2-

• Solid magnesium, on the reactant side, has an oxidation number of ____. The

magnesium ion product has an oxidation number of ____. Magnesium’s oxidation

number changes from 0 to +2. Magnesium is oxidized because it loses _________

electrons. To state this reaction more clearly,

_______________________________________________. Oxygen gas, on the reactant

side, has an oxidation number of _______. The oxygen ion product has an oxidation

number of _______. Oxygen’s oxidation number changes from 0 to -2. Oxygen is

reduced because it gains _________ electrons. Following our magnesium oxide example

further, the reduction reaction that accompanies the oxidation of magnesium is the

reduction of oxygen.

______________________________________________________ When magnesium

reacts with oxygen, each magnesium atom transfers two electrons to each oxygen atom.

The two magnesium atoms become Mg2+ ions and the two oxygen atoms become O2– ions

(oxide ions).

A reaction in which electrons are ______________________________ from one atom to another

is called an oxidation–reduction reaction. For simplicity, chemists often refer to oxidation–

reduction reactions as ____________________ reactions.

Now consider the single-replacement reaction in which chlorine in an aqueous solution replaces

bromine from an aqueous solution of potassium bromide.

Complete Chemical Equation: 2 KBr (aq) + Cl2 (aq) 2 KCl (aq) + Br2 (aq)

Net Ionic Equation: 2 Br- (aq) + Cl2 (aq) 2 Cl- (aq) + Br2 (aq)

• Note that chlorine “steals” electrons from bromide ions to become

_______________________ ions. When the bromide ions lose their extra electrons, the

two bromine atoms form a covalent bond with each other to produce Br2 molecules. The


result of this reaction, the characteristic color of elemental bromine in solution. The

formation of the covalent bond by ________________________ of electrons also is an

oxidation–reduction reaction.

• Note that there is no change in the oxidation number of potassium. The potassium ion

takes no part in the reaction and as a result DOES NOT appear in the net ionic equation.

It is called a _________________________________ ion.

Can oxidation occur without reduction? By our definitions, oxidation and reduction are

complementary processes; oxidation cannot occur unless reduction also occurs.

• Determine which element is oxidized and which element is reduced in the following

reaction. (Provide the oxidation numbers.)

a) 3Cu + 2NO3- + 8H+ 3Cu2+ + 2NO + H2O

b) 2KNO3 2KNO2 + O2

c) H2 + CuO Cu + H2O

d) H2S + NO3- SO4

2- + NO2

How DO Oxidation and Reduction Differ?

LEO the lion says GER or, for short, LEO GER

This phrase will help you remember that Loss of Electrons is Oxidation, and Gain of Electrons

is Reduction.

• Determine how many electrons are lost and how many electrons are gained in the

following reaction. (Provide the oxidation numbers.)

a) Fe2+ + MnO4- Fe3+ + Mn2+

b) Na2SnO2 + Bi(OH)3 Bi + Na2SnO3 + H2O

c) 2Fe + O2 + 2H2O 2Fe(OH)2


Redox and Electronegativity

The chemistry of oxidation–reduction reactions is not limited to atoms of an element changing to

ions or the reverse.

Example: N2 (g) + 3H2 (g) → 2NH3 (g)

• Nitrogen’s oxidation number changes from _______ to _______; therefore nitrogen is

____________________________. For the purpose of studying oxidation–reduction

reactions, the more electronegative atom (nitrogen) is treated as if it had been reduced by

gaining electrons from the other atom. Hydrogen’s oxidation number changes from

_______ to _______; therefore hydrogen is _______________________. The less

electronegative atom (hydrogen) is treated as if it had been oxidized by losing electrons.

Half-Reactions

The oxidation process and the reduction process of a redox reaction can each be expressed as a

half-reaction.

• For example, consider the unbalanced equation for the formation of aluminum bromide.

Al + Br2 → AlBr3

• The oxidation half-reaction shows the loss of electrons by aluminum. Al → Al3+ + 3e-

The reduction half-reaction shows the gain of electrons by bromine. Br2 + 2e- →2Br-

Write balanced half-reactions for each of the following molecular equations.

a) K + S → K2S

b) Ca + Cl2 → CaCl2

c) AlBr3 → Al + Br2

d) Zn3P2 → Zn + P

Practical Applications of Redox

A common application of redox chemistry is to remove ____________________________ from

metal objects, such as a silver cup. When you add chlorine ________________________ to

your laundry to whiten clothes, you are using an aqueous solution of sodium hypochlorite

(NaClO). Chlorine is ________________________ in the process. Hydrogen peroxide (H2O2)


can be used as an antiseptic because it _____________________________ some of the vital

biomolecules of germs, or to lighten hair because it oxidizes the dark pigment of the hair. When

you put a battery into a flashlight, radio, or CD player, you complete the electrical circuit of a

galvanic cell(s), providing a path for the electrons to flow through as they move from the site of

____________________________ to the site of the reduction. Electroplating is important in

protecting objects from ______________________________ and uses the process of redox.

Reduction of silver ions onto cheaper metals forms _______________________________.

Homework / Practice

What is the oxidation number of .

1) N in NO3¯

2) C in CO32¯

3) Cr in CrO42¯

4) Cr in Cr2O72¯

5) Fe in Fe2O3

6) Pb in PbOH+

7) V in VO2+

8) V in VO2+

9) Mn in MnO4¯

10) Mn in MnO42¯

Balance each half-reaction for atoms and charge:

11) Cl2 ---> Cl¯

12) Sn ---> Sn2+

13) Fe2+ ---> Fe3+

14) I3¯ ---> I¯

Separate each of these redox reactions into their two half-reactions (but do not balance):

15) Sn + NO3¯ ---> SnO2 + NO2

16) HClO + Co ---> Cl2 + Co2+

17) NO2 ---> NO3¯ + NO


In each of the following, identify what is being oxidized and what is being reduced.

18) Cu+2 + Fe ---> Fe+2 + Cu

19) Co + Sn+2 ---> Co+2 + Sn

20) 2 Cr + 3 Sn+2 ---> 2 Cr+3 + 3 Sn

21) CH4 + 2 O2 ---> CO2 + 2H2O

22) Mg + CO2 ---> 2MgO + C

23) 4H+1 + NO3-1 + 3 Fe+2 ---> 2 H2O + NO + 3 Fe+3

24) S-2 + 2 NO3-1 + 4H+1 ---> SO2 + NO2 + 2H2O

25) 2 NH4+1 + 2 NO3-1 ---> 2 N2 + 4 H2O + O2

Oxidation and Reduction Practice Test

1. Explain what takes place in an oxidation-reduction reaction.

Directions: Identify the oxidation number for the listed element within each compound or ion

2. Cr in Cr2O72¯ __________

3. Pb in PbOH+ __________

4. V in VO2+ __________

5. Mn in Mn2O7 __________

6. S in H2SO4 __________

7. Br in BrO3- __________


Directions: Label the oxidation states on all of the elements and trace the paths of oxidation and reduction.

8. HNO3 + 3Cu2O 6Cu(NO3)2 + 2NO + 7H2O

9. H2SO4 + HI H2S + I2 + H2O

Directions: Balance each half-reaction for atoms and charge:

10. Sn ---> Sn2+

11. Cr5+ Cr3+

12. Ag Ag1+

Directions: Separate each of these redox reactions into their two half-reactions:

13. Sn + NO3¯ ---> SnO2 + NO2

14. C2H4 + 3O2 2CO2 + 2H2O

15. 2Ca + O2 ® 2CaO


16. The oxidation number of sulfur in H2SO4 isa. +2b. +3

c. +4d. +6

e. +8

17. What is the oxidation number of chromium in the ionic compound Na2Cr2O7?a. +2 b. +6

18. What is the oxidation number of nitrogen in the molecule N2?a. 0b. 3

c. 5d. 7

19. In the following reaction, the oxidation numbers on sulfur are:NaCl + H2SO4 + MnO2 → Na2SO4 + MnSO4 + H2O + Cl2

a. +6, +6 and +4 respectively b. +6, +6 and +6 respectively c. +4, +6 and +4 respectively

d. +4, +4 and +4 respectively e. +4, +6 and +6 respectively


20. NaCl + H2SO4 + MnO2 → Na2SO4 + MnSO4 + H2O + Cl2

Which of the reactants contains an element that is oxidized?a. H+ b. Mn4+

c. Na+ d. Cl-

e. O2-

21. In the balanced molecular equation for the neutralization reaction between phosphoric acid and potassium hydroxide, the products are:

a. KPO4 + H3OH b. 3H2O c. None of thesed. K+(aq) + PO4

3-(aq) + 3H+ + 3OH- e. K3PO4 + 3H2O

22. In the reaction 4Al + 3O2 → 2Al2O3 the substance oxidized is:a. O2- b. O2

c. Al3+ d. Al

e. None of these, because this is not a redox reaction

23. In which of the following compounds does sulfur have an oxidation state of +4?a. H2SO4 b. H2S c. H2SO3 d. MgSO4

e. SO3

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