matter—properties and changesmatter—properties and...

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

, a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

, Inc

.SOLUTIONS MANUALCHAPTER 3

Matter—Properties and ChangesMatter—Properties and Changes

Solutions Manual Chemistry: Matter and Change • Chapter 3 35

Section 3.1 Properties of Matterpages 70–75

Problem-Solving Lab 1. Explain why the flow of a compressed gas must

be controlled for practical and safe use.

The flow of compressed gas must be controlled to control the amount and the rate at which gas is released.

2. Predict what would happen if the valve on a full tank of compressed gas were suddenly opened all the way or if the tank were accidentally punctured.

Without the regulator device, the gas would rush out of the tank with a force powerful enough to transform the tank into a dangerous, uncontrolled projectile.

Section 3.1 Assessmentpage 75

1. Create a table that describes the three common states of matter in terms of their shape, volume, and compressibility.

Volume Shape Compressibility

Solid Definite Definite Incompressible

Liquid Definite Takes shape of container and fills container

to the extent of its own volume

Virtually incompressible

Gas Fills volume of container

Takes shape of container

Compressible

2. Describe the characteristics that identify a sample of matter as being a substance.

The sample of matter must have a uniform and unchanging composition to be a substance.

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

a. Iron and oxygen form rust.

chemical

b. Iron is more dense than aluminum.

physical

c. Magnesium burns brightly when ignited.

chemical

d. Oil and water do not mix.

physical

e. Mercury melts at �39°C.

physical

4. Organize Create a chart that compares physical and chemical properties. Give two examples for each type of property.

The chart should make clear that physical properties can be observed without changing the composition of the sample, which is not the case for chemical properties. Mass and density are examples of physical properties. Fermentation and rusting are examples of chemical properties.

Section 3.2 Changes in Matterpages 76–79

Practice Problemspage 78

5. Use the data in the table to answer the following questions.

Before Reaction After Reaction

Aluminum 10.3 g 0.0 g

Liquid bromine 100.0 g 8.5 g

Compound 0.0 g

Aluminum and Liquid Bromine Reaction

How many grams of bromine reacted? How many grams of compound were formed?

amount of bromine that reacted �100.0 g � 8.5 g � 91.5 g

amount of compound formed �100.0 g � 10.3 g � 8.5 g � 101.8 g

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

, a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

, Inc

.

36 Chemistry: Matter and Change • Chapter 3 Solutions Manual

SOLUTIONS MANUALCHAPTER 3

6. From a laboratory process designed to sepa-rate water into hydrogen and oxygen gas, a student collected 10.0 g of hydrogen and 79.4 g of oxygen. How much water was originally involved in the process?

massreactants � massproducts

massreactants � masswater electrolyzed

massproducts � masshydrogen � massoxygen

masswater electrolyzed � masshydrogen � massoxygen

masswater electrolyzed � 10.0 g � 79.4 g � 89.4 g

7. A student carefully placed 15.6 g of sodium in a reactor supplied with an excess quantity of chlorine gas. When the reaction was complete, the student obtained 39.7 g of sodium chloride. Calculate how many grams of chlorine gas reacted. How many grams of sodium reacted?


masssodium � masschlorine � masssodium chloride

masssodium � 15.6 g

masssodium chloride � 39.7 g

Substituting and solving for masschlorine yields 15.6 g � masschlorine � 39.7 g

masschlorine � 39.7 g � 15.6 g � 24.1 g used in the reaction.

Because the sodium reacts with excess chlorine, all of the sodium (15.6 g) is used in the reaction.

8. A 10.0-g sample of magnesium reacts with oxygen to form 16.6 g of magnesium oxide. How many grams of oxygen reacted?


massmagnesium � massoxygen � massmagnesium oxide

massmagnesium � 10.0 g

massmagnesium oxide � 16.6 g

10.0 g � massoxygen � 16.6 g

massoxygen � 16.6 g � 10.0 g � 6.6 g

9. Challenge 106.5 g of HCl(g) react with an unknown amount of NH3(g) to produce 157.5 g of NH4Cl(s). How many grams of NH3(g) reacted? Is the law of conservation of mass observed in the above reaction? Justify your answer.

157.5 g � 106.5 g � 51 g

Yes. Mass of reactants equals mass of products.


10. Classify each example as a physical change or a chemical change.

a. crushing an aluminum can

physical

b. recycling used aluminum cans to make new aluminum cans

physical

c. aluminum combining with oxygen to form aluminum oxide

chemical

11. Describe the results of a physical change and list three examples of physical change.

During a physical change, a substance is altered but its composition does not change. Examples will vary but may include changes such as melting, freezing, boiling, bending, and tearing.

12. Describe the results of a chemical change. List four indicators of chemical change.

During a chemical change, the composition of a substance is altered. Possible indicators of chemical change include a change in color, odor, temperature, and the formation of a gas or solid from a liquid.

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

, a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

, Inc

.



13. Calculate Solve each of the following.

a. In the complete reaction of 22.99 g of sodium with 35.45 g of chlorine, what mass of sodium chloride is formed?

masssodium chloride � masssodium � masschloride

masssodium chloride � 22.99 g � 35.45 g � 58.44 g

b. A 12.2-g sample of X reacts with a sample of Y to form 78.9 g of XY. What is the mass of Y that reacted?

massX � massY � massXY

massY � massXY � massX �78.9 g � 12.2 g � 66.7 g

14. Evaluate A friend tells you, “Because composition does not change during a physical change, the appearance of a substance does not change.” Is your friend correct? Explain.

The statement is incorrect. While the composition does not change, a change in appearance often accompanies a physical change.

Section 3.3 Mixtures of Matterpages 80–83


15. Classify each of the following as either a heterogeneous or homogeneous mixture.

a. tap water

homogeneous

b. air

homogeneous

c. raisin muffin

heterogeneous

16. Compare mixtures and substances.

Substances have a constant composition, mixtures do not. Each substance in a mixture retains its own properties, whereas the properties of a substance are different from those of the elements that comprise it.

17. Describe the separation technique that could be used to separate each of the following mixtures.

a. two colorless liquids

distillation

b. a nondissolving solid mixed with a liquid

filtration

c. red and blue marbles of same size and mass

manually separating the marbles by color

18. Concept Map Sketch a rough chart that summarizes the relationship between matter, elements, mixtures, compounds, pure substances, homogeneous mixtures, and heterogeneous mixtures.

Chart will be similar to Figure 3.19.

Heterogeneousmixtures

dirt, blood,milk

lemonade, gasoline,steel

oxygen, gold,iron

salt, baking soda,sugar

Homogeneousmixtures

Elements Compounds

Matter

Mixtures

Physicalchanges

Chemicalchanges

Pure substances

Section 3.4 Elements and Compoundspages 84–90

Practice Problemspage 88

19. A 78.0-g sample of an unknown compound contains 12.4 g of hydrogen. What is the percent by mass of hydrogen in the compound?

Percent by masshydrogen � masshydrogen

__ masscompound � 100

Percent by masshydrogen � 12.4 g

_ 78.0 g

� 100 � 15.9%

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

, a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

, Inc

.



20. If 1.0 g of hydrogen reacts completely with 19.0 g of fluorine, what is the percent by mass of hydrogen in the compound that is formed?

masscompound � 1.0 g � 19.0 g � 20.0 g

percent by masshydrogen � masshydrogen

__ masscompound � 100

percent by masshydrogen � 1.0 g

_ 20.0 g

� 100 � 5.0%

21. If 3.5 g of X reacts with 10.5 g of Y to form the compound XY, what is the percent by mass of X in the compound? The percent by mass of Y?

massXY � 3.50 g � 10.5 g � 14.0 g

percent by massX � massX _ massXY

� 100

percent by massX � 3.50 g

_ 14.0 g

� 100 � 25% X

percent by massY � massY _ massXY

� 100

percent by massY � 10.5 g

_ 14.0 g

� 100 � 75% X

22. Two unknown compounds are tested. Compound I contains 15.0 g of hydrogen and 120.0 g of oxygen. Compound II contains 2.0 g of hydrogen and 32.0 g of oxygen. Are the compounds the same?

Compound I: mass percentagehydrogen � 15.0 g /(15.0 g � 120.0 g) � 11.1%

Compound II: mass percentagehydrogen � 2.0 g (2.0 g � 32.0) � 5.9%

Because the mass compositions of the compounds are different, the compounds themselves must be different.

23. Challenge All you know about two unknown compounds is that they have the same percent by mass of carbon. With only this information, can you be sure the two compounds are the same? Explain.

No, you cannot be sure. Having the same mass percentage of a single element does not guarantee that the composition of each compound is the same.


24. Compare and contrast elements and compounds.

Elements cannot be broken down into simpler substances by ordinary chemical means, whereas compounds can.

25. Describe the basic organizational feature of the periodic table of elements.

The periodic table is organized by rows (called “periods”) and columns (called “groups” or “families”). Elements in the same group have similar chemical and physical properties. The patterns of similar properties repeat from period to period.

26. Explain how the law of definite proportions applies to compounds.

The law of definite proportions describes the mass composition of a substance.

27. State the type of compounds that are compared in the law of multiple proportions?

The law of multiple proportions relates the compositions of two compounds composed of the same elements.

28. Complete the table, and then analyze the data to determine if Compounds I and II are the same compound. If the compounds are different, use the law of multiple proportions to show the relationship between them.

Compound Total Mass (g)

Mass Fe (g)

Mass O (g)

Mass % Fe

Mass % O

I 75.00 52.46 22.54 69.05 30.05

II 56.00 43.53 12.47 77.73 22.27

Analysis Data of Two Iron Compounds

Compound I mass percent Fe � 69.95%; mass percent O � 30.05%. Compound II mass percent Fe � 77.73%; mass percent O � 22.27%. The compounds are not the same.

Compound I: Fe:O � 52.46 g/22.54 g � 2.327

Compound II, Fe:O � 43.53 g/12.47 g � 3.491.

The relative mass ratio of Fe in compound I and compound II is 2.327:3.491 � 0.667 � 2:3.

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

, a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

, Inc

.



29. Calculate the mass percent of hydrogen in water and the mass percent of oxygen in water.

Mass % of hydrogen in water �

20 _ 100

� 100% � 11%

Mass % of oxygen in water �

160 _ 180

� 100% � 89%

30. Graph Create a graph that illustrates the law of multiple proportions.

Graph should be similar to Figure 3.20.

a

b

c

Compound I

1.000

2.000

Mas

s (g

)

Cu

Cl

Compound II

1.000

2.000

Mas

s (g

)

Cu Cl

Mass RatioComparison

1.000

2.000

Mas

s (g

)

I

II

Chapter 3 Assessmentpages 94–97

Section 3.1

Mastering Concepts 31. List three examples of substances. Explain why

each is a substance.

Answers will vary. Water, salt, and sugar are all substances. Each is a substance because it has a unique and unchanging composition.

32. Is carbon dioxide gas a pure substance? Explain.

Yes. Carbon dioxide has a constant composition.

33. List at least three physical properties of water.

Answers will vary. Water is odorless, colorless, a liquid, freezes at approximately 0°C, and boils at approximately 100°C.

34. Identify each of the following as an extensive or intensive physical property.

a. melting point

intensive

b. mass

extensive

c. density

intensive

d. length

extensive

35. “Properties are not affected by changes in temperature and pressure.” Is this statement true or false? Explain.

The statement is false. Properties are affected by changes in temperature, pressure. For example, the phase of a substance is determined by its temperature and pressure. Other specific examples will vary.

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

, a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

, Inc

.



36. List the three states of matter and give an example for each state. Differentiate between a gas and a vapor.

Solid (ice), liquid (water), and gas (helium). Substances that are in the gas phase at room temperature are referred to as gases, whereas substances such as water vapor that are not gases at room temperature are vapors.

Vapors of volatile solvents such as acetone and methanol escape if the solvent is left opened at room temperature.

37. Classify each as either solid, liquid, or gas at room temperature.

a. milk

liquid

b. air

gas

c. copper

solid

d. helium

gas

e. diamond

solid

f. candle wax

solid

38. Classify each as a physical property or a chemical property.

a. aluminum has a silvery color

physical

b. gold has a density of 19 g/cm3

physical

c. sodium ignites when dropped in water

chemical

d. water boils at 100°C

physical

e. silver tarnishes

chemical

f. mercury is a liquid at room temperature

physical

39. A carton of milk is poured into a bowl. Describe the changes that occur in the milk’s shape and volume.

The volume of the milk remains unchanged. Milk, which is a liquid, conforms to the shape of its container, thus the shape of the milk changes as it is poured from the carton into the bowl.

40. Boiling Water At what temperature would 250 mL of water boil? 1000 mL? Is the boiling point an intensive or extensive property? Explain.

100°C. 100°C. Boiling point is an intensive property since it is independent of quantity or amount.

Mastering Problems 41. A scientist is given the task of identifying an

unknown compound on the basis of its physical properties. The substance is a white solid at room temperature. Attempts to determine its boiling point were unsuccessful. Using Table 3.6, name the unknown compound.

Substance ColorState at

25°CBoiling Point

(°C)

Oxygen colorless gas �183

Water colorless liquid 100

Sucrose white solid decomposes

Sodium chloride white solid 1413

Physical Properties of Common Substances

Table 3.6 shows two compounds that are white solids. Sucrose decomposes before a boiling point is determined. Therefore, the unknown substance is sucrose.

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

, a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

, Inc

.



Section 3.2

Mastering Concepts 42. Label each set of diagrams in Figure 3.22 as

physical or chemical change.

a. physical b. chemical

43. Classify each as a physical change or a chemical change.

a. breaking a pencil in two

physical

b. water freezing and forming ice

physical

c. frying an egg

chemical

d. burning wood

chemical

e. leaves turning color in the fall

chemical

44. Ripening Is the process of the ripening a chemical or physical change? Explain.

It is a chemical change. A green banana has different properties compared to a yellow banana.

45. Is a change in phase a physical or a chemical change?

It’s a physical change. The composition of the substance does not change.

46. List four indicators that a chemical change has probably taken place.

Probable indicators of a chemical reaction include a change in color, odor, or temperature, and/or the production of a gas or a solid upon mixing.

47. Salt Sodium and chlorine combine to form sodium chloride. List the reactants and products of this reaction.

Sodium and chlorine are the reactants, while sodium chloride is the product formed. Iron � oxygen 0 iron oxide.

48. Burning Candle After burning for three hours, a candle has lost half of its mass. Explain why this example does not violate the law of conservation of mass.

The mass of the candle is conserved if you consider the gaseous products from the reaction.

49. Describe the difference between a physical change and a chemical change.

A physical change alters a substance without changing its composition, while a chemical change involves a change in composition.

Mastering Problems 50. Ammonia Production A 28.0-g sample of

nitrogen gas combines completely with 6.0 g of hydrogen gas to form ammonia. What is the mass of ammonia the formed?

massnitrogen � masshydrogen � massammonia

massammonia � 28.0 g � 6.0 g � 34.0 g

51. A 13.0-g sample of X combines with a 34.0-g sample of Y to form the compound XY2. What is the mass of the reactants?

X and Y are the reactants. The formula of the compound formed is not important.

massreactants � massproducts � 13.0 g � 34.0 g � 47.0 g

52. If 45.98 g of sodium combines with an excess of chlorine gas to form 116.89 g sodium chlo-ride, what mass of chlorine gas is used in the reaction?

masssodium � masschlorine � masssodium chloride

masschlorine � masssodium chloride � masssodium

masschlorine � 116.89 g – 45.98 g � 70.91 g

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

, a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

, Inc

.



53. A substance breaks down into its component elements when it is heated. If 68.0 g of the substance is present before it is heated, what is the combined mass of the component elements after heating?

massreactants � massproducts � 68.0 g

Regardless of what the compound decomposes into, mass must be conserved.

54. Copper sulfide is formed when copper and sulfur are heated together. In this reaction, 127 g of copper reacts with 41 g of sulfur. After the reaction is complete, 9 g of sulfur remains unreacted. What is the mass of copper sulfide formed?

masssulfur used in the reaction � initial mass of sulfur � mass remaining after reaction

masssulfur � masssulfur used in the reaction � 41 g � 9 g � 32 g

masscopper sulfide � masscopper � masssulfur � 127 g � 32 g � 159 g

55. When burning 180 grams of glucose in the presence of 192 grams of oxygen, water and carbon dioxide are produced. If 108 grams of water are produced; how many grams of CO2 are produced?

massglucose � massoxygen � masscarbon dioxide � masswater

180 g � 192 g � 108 g � masscarbon dioxide

masscarbon dioxide � 264 g.

Section 3.3

Mastering Concepts 56. Describe the characteristics of a mixture.

Mixtures are a physical blend of two or more substances in any proportion. Mixtures do not have a constant composition. The properties of the mixture are largely those of its component substances.

57. Name the separation method illustrated in Figure 3.23.

distillation

58. Describe a method that could be used to separate each of the following mixtures.

a. iron filings and sand

A magnet can be used to draw the iron filings from the sand.

b. sand and salt

Add water to the mixture to dissolve the salt. Filter the mixture to remove the sand, and then boil off the water so only the salt remains.

c. the components of ink

Paper chromatography should be used to separate the components of the ink. If enough ink is available, distillation may also be used, but is far more complicated than chromatography.

d. helium and oxygen gases

Cool the gas mixture until it condenses, then distill the condensate.

59. “A mixture is the chemical bonding of two or more substances in any proportion.” Is this statement true or false. Explain.

The statement is false because mixtures are physical blends of substances, not a chemical bonding of substances.

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

, a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

, Inc

.



60. Which of the following are the same and which are different?

a. a substance and a pure substance

same

b. a heterogeneous mixture and a solution

different

c. a substance and a mixture

different

d. a homogeneous mixture and a solution

same

61. Describe how a homogeneous mixture differs from a heterogeneous mixture.

Homogeneous mixtures contain a single phase. Heterogeneous mixtures may have many phases.

62. Seawater is composed of salt, sand and water. Is seawater a heterogeneous or homogeneous mixture? Explain.

Heterogeneous mixture. Composition is not uniform.

63. Iced Tea Use iced tea with and without ice cubes as examples to explain homogeneous and heterogeneous mixtures. If you allow all of the ice cubes to melt, what type of mixture remains?

Iced tea with ice cubes is a heterogeneous mixture.

Iced tea without ice cubes is a homogeneous mixture.

When all ice cubes melt the remaining mixture is homogeneous.

64. Chromatography What is chromatography and how does it work?

Chromatography is a technique used to separate components of a mixture.

Section 3.4

Mastering Concepts 65. State the definition of element.

An element is a substance that cannot be broken down into simpler substances by physical or chemical means.

66. Correct the following statements:

a. An element is a combination of two or more compounds.

A compound is combination of two or more elements.

b. When a small amount of sugar is completely dissolved in water, a heterogeneous solution is formed.

When a small amount of sugar is completely dissolved in water, a homogeneous solution is formed.

67. Name the elements contained in the following compounds.

a. sodium chloride (NaCl)

sodium and chlorine

b. ammonia (NH3)

nitrogen and hydrogen

c. ethanol (C2H6O)

carbon, hydrogen, and oxygen

d. bromine (Br2)

bromine

68. What was Dmitri Mendeleev’s major contribu-tion to the field of chemistry?

Mendeleev developed the first widely accepted periodic table of elements.

69. Is it possible to distinguish between an element and a compound? Explain.

Yes, elements can be distinguished from compounds. Compounds can be broken down into their component elements, whereas elements cannot be broken down into simpler substances.

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

, a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

, Inc

.



70. How are the properties of a compound related to those of the elements that comprise it?

The properties of a compound are unique to that compound and are different from those of its component elements.

71. Which law states that a compound always contains the same elements in the same propor-tion by mass?

The law of definite pro portions

72. a. What is the percent by mass of carbon in 44 grams of carbon dioxide, CO2?

Percent by mass � masscarbon __ masscarbon dioxide

� 100

� 12 g

_ 44 g

� 100 � 27%

b. What is the percent by mass of oxygen in 44 grams of carbon dioxide, CO2?

Percent by mass � massoxyegn

__ masscarbon dioxide � 100

� 32 g

_ 44 g

� 100 � 73%

or (100% � 27% � 73% ) if you use the result from part (a)

73. Complete Table 3.7 by classifying the following compounds as: 1:1 or 2:2, 1:2 or 2:1, and 1:3 or 3:1.

Compound Simple Whole-Number Ratiosof Elements

NaCl 1:1

CuO 1:1

H2O 2:1

H2O2 2:2

Ratios of Elements in Compounds

Mastering Problems 74. A 25.3-g sample of an unknown compound

contains 0.8 g of oxygen. What is the percent by mass of oxygen in the compound?

Mass Percentageoxygen � massoxygen

__ masscompound � 100 �

0.8 g

_ 25.3 g

� 100 � 3%

75. Magnesium combines with oxygen to form magnesium oxide. If 10.57 g of magnesium reacts completely with 6.96 g of oxygen, what is the percent by mass of oxygen in magnesium oxide?

Mass percentageoxygen � 6.96 g/(10.57 g � 6.96 g) � 39.7%

76. When mercury oxide is heated, it decomposes into mercury and oxygen. If 28.4 g of mercury oxide decomposes, producing 2.0 g of oxygen, what is the percent by mass of mercury in mercury oxide?

Mass Percentagemercury � massmercury

__ massmercury oxide � 100

� 28.4 g � 2.0 g

__ 28.3 g � 100

� 93.0%

77. Carbon reacts with oxygen to form two different compounds. Compound I contains 4.82 g of carbon for every 6.44 g of oxygen. Compound II contains 20.13 g of carbon for every 53.7 g of oxygen. What is the ratio of carbon to a fixed mass of oxygen for the two compounds?

Compound massC (g)

massO (g)

massC/massO

I 4.82 6.44 4.82 g/6.44 g � 0.748

II 20.13 53.7 20.13 g/53.7 g � 0.375

(mass ratiocompound I/mass ratiocompound II) � (0.748/0.375) � 1.99 � ~2

The ratio of carbon to a fixed mass of oxygen in compound I is 0.748:1, while in compound II it is 0.375:1. The ratio of carbon to oxygen in Compound I is twice that in Compound II.

78. A 100-g sample of an unknown salt contains 64 g of chlorine. What is the percent by mass of chlorine in the compound?

Mass Percentagechlorine � masschlorine __ masscompound

� 100

� 64 g

_ 100 g

� 100 � 64%

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

, a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

, Inc

.



79. Which law would you use to compare CO and CO2? Explain. Without doing any calculation, which of the two compounds CO and CO2 has the highest percent by mass of oxygen in the compound.

The law of multiple proportions. CO2 will have the highest percent by mass of oxygen because it has more oxygen atoms for the same number of carbon atom.

80. Complete Table 3.8.

Elements in Compounds

Mass of Second Element Mass of Mass of Mass in theCom- Compound Oxygen % of Compoundpound (g) (g) Oxygen (g)

CuO 80.0 16 20 64

H2O 18.0 16 89 2

H2O2 34.0 32 94 2

CO 28.0 16 57 12

CO2 44.0 32 73 12

Mixed Review 81. Which state(s) of matter are compressible?

Which state(s) of matter are not compressible? Explain.

Gases are the most compressible state of matter, solids the least. Liquids are virtually incompressible. Compressibility is determined by the amount of space between particles in each state. Gases have the greatest amount of space between particles, solids the least.

82. Classify each mixture as homogeneous or heterogeneous.

a. brass (an alloy of zinc and copper)

homogeneous

b. a salad

heterogeneous

c. blood

heterogeneous

d. powdered drink mix dissolved in water

homogeneous

83. Phosphorus combines with hydrogen to form phosphine. In this reaction, 123.9 g of phosphorus combines with excess hydrogen to produce 129.9 g of phosphine. After the reaction, 310 g of hydrogen remains unreacted. What mass of hydrogen is used in the reaction? What was the initial mass of hydrogen before the reaction?

Masshydrogen �129.9 g � 123.9 g � 6.0 g

Initial masshydrogen � 310 g � 6.0 g � 316 g

84. If you have 100 particles of hydrogen and 100 particles of oxygen, how many units of water can you form? Will you use all the particles of both elements? If not, what will remain?

50 units of water can be formed.No, 50 particles of oxygen will remain.

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

, a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

, Inc

.



85. Classify each substance as a pure substance, a homogeneous mixture, or a heterogeneous mixture.

a. air

homogeneous mixture

b. aerosol

heterogeneous mixture

c. soil

homogeneous or heterogeneous mixture depending on the soil sample

d. water

pure substance

e. sediment


f. muddy water


86. Indicate each as a homogenous mixture, a heterogeneous mixture, a compound, or an element.

a. Pure drinking water—compound

b. Salty water—homogenous mixture

c. Helium—element

d. Seawater—heterogeneous mixture

e. Air—homogenous mixture

87. Cooking List physical properties of eggs before and after they are cooked. Based on your observations, does a physical change or chemical change occur when eggs are cooked? Justify your answer.

Eggs before cooking: liquid, white (clear) and bright yellow

Eggs after cooking: solid opaque white and dull yellow

Chemical change.

88. Ice Cream You might have noticed that while eating ice cream on a very hot day some of the ice cream begins to melt. Are the observed changes in the state of the ice cream a physical or chemical change? Justify your answer.

Ice cream melting is a physical change since the chemical composition remains constant.

89. Pizza Is pizza a homogeneous or heteroge-neous mixture? Explain.

A pizza is a heterogeneous mixture because the individual parts of the pizza–dough, sauce, cheese, toppings–remain separate.

90. Sodium reacts chemically with chlorine to form sodium chloride. Is sodium chloride a mixture or a compound?

Sodium chloride is a compound because it is a substance composed of the two elements sodium and chlorine, and it is formed by a chemical reaction.

91. Is air a solution or heterogeneous mixture? What technique can be used to separate air into its components?

Air is a solution. Air can be separated into its components, oxygen, nitrogen and carbon dioxide by using gas chromatography.

92. Does the combination of the following elements yield a compound or a mixture:

a. H2(g) � O2(g) 0 Water

compound

b. N2(g) � O2(g) 0 Air

mixture

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

, a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

, Inc

.



Think Critically 93. Interpret Data A compound contains

elements X and Y. Four samples with different masses were analyzed, and the masses of X and Y in each sample were plotted on a graph shown in Figure 3.24. The samples are labeled I, II, III, and IV.

4 6 8 1020

Mas

s of

X (

g)

40

30

20

10

0

Mass of Y (g)

I

IV II

III

Masses of Elements

a. Which samples are from the same compound? How do you know?

Samples I, III, and IV are the same compound. A straight line can be drawn through these three plotted points. The slope of the line is equivalent to ratio MassX/MassY. The fact that all three points are on the same line shows that they all have the same mass ratio of X to Y and must be the same compound.

b. What is the approximate ratio of mass X to mass Y in the samples that are from the same compound?

Mass ratio of X to Y for samples I, III, and IV is 3.75:1.

c. What is the approximate ratio of mass X to mass Y in the sample(s) that are not from the same compound?

Sample II mass ratio is 1.9:1

94. Apply Air is a mixture of many gases, primarily nitrogen, oxygen, and argon. Could distillation be used to separate air into its component gases? Explain.

Yes. If the mixture of gases is cooled sufficiently, it will condense into a mixture of liquids. This mixture could then be distilled.

95. Analyze Is gas escaping from an opened soft drink an example of chemical or physical change? Explain.

Physical change. The composition of CO2 gas is the same inside and outside of the soft drink.

96. Apply Give examples of heterogeneous mixtures for the systems listed in Table 3.9.

Heterogeneous Mixtures

System Example

Liquid-liquid Water and oil

Solid-liquid Sand and water

Solid-solid Iron filings and sugar

Challenge Problem 97. A sample of a certain lead compound contains

6.46 grams of lead for each gram of oxygen. A second sample has a mass of 68.54 g and contains 28.76 g of oxygen. Are the two samples the same?

Sample I: masslead/massoxygen � 6.46

Sample II: masslead/massoxygen � (68.54 g � 28.76 g)/28.76 g � 1.383

The two samples are not the same because the two masslead/massoxygen ratios are not the same.

Cumulative Review 98. What is chemistry? (Chapter 1)

Chemistry is the study of matter and the changes that it undergoes.

99. What is mass? Weight? (Chapter 1)

Mass is the measure of the amount of matter an object contains. It is measured on a balance. The weight of an object is the amount of gravitational pull acting on the mass of an object. It is measured on a scale.

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

, a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

, Inc

.



100. Express the following in scientific notation. (Chapter 2)

a. 34,500

3.45 � 104

b. 2665

2.665 � 103

c. 0.9640

9.640 � 10�1

d. 789

7.89 � 102

e. 75,600

7.56 � 104

f. 0.002189

2.189 � 10�3

101. Perform the following operations. (Chapter 2)

a. 107 � 103

1010

b. (1.4 � 10�3) � (5.1 � 10�5)

7.1 � 10�8

c. (2 � 10�3) � (4 � 105)

8 � 102

102. Convert 65°C to kelvins. (Chapter 2)

273 � 65°C � 338 K

103. Graph the data in Table 3.10. What is the slope of the line? (Chapter 2)

Energy Released by Carbon

Mass (g) Energy Released (kJ)

1.00 33

2.00 66

3.00 99

4.00 132

0

20

40

60

80

100

120

140

0 1.00 2.00 3.00 4.00

Energy Released by Carbon

Mass (g)

Ener

gy

rele

ased

(kJ

)

Slope: 33 kJ/g

Writing in Chemistry 104. Synthetic Elements Select a synthetic

element, and prepare a short written report on its development. Be sure to discuss recent discoveries, list major research centers that conduct this type of research, and describe the properties of the synthesized element.

Student answers will vary. Students can obtain some information on the elements from the Merck Index or the CRC Handbook of Chemistry and Physics.

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

, a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

, Inc

.



Document-Based Questions

Pigments Long before scientists understood the properties of elements and compounds, artists used chemistry to create pigments from natural materials. Table 3.11 gives some examples of such pigments used in ancient times.

Data obtained from: Orna, Mary Virginia. 2001. Chemistry, color, and art. Journal of Chemical Education 78 (10): 1305

Common Artists’ Pigments Used in Early Times

Common Name Chemical Identity Comments

Charcoal elemental carbon(carbon black)

produced by dry distillation of wood in a closed vessel

Egyptian blue

calcium copper tetrasilicate,CaCuSi4O10

crystalline compound containing some glass impurity

Indigo indigotin,C16H10N202

derived from different plants of the genus indigofera

Iron oxide red

Fe2O3 in continuous use in all geographic regions and time periods

Verdigris dibasic acetate of copperCu(C2H3O2)2 • 2Cu(OH)2

other copper compounds, including carbonate, are also called verdigris.

105. a. Determine the mass percent of carbon in charcoal, indigo and verdigris.

Charcoal: mass percentcarbon � 100%

Indigo: mass percentcarbon � 73%

Verdigris: mass percentcarbon � 14%

b. Determine the mass percent of oxygen in iron oxide and Egyptian blue.

Iron oxide: mass percentoxygen � 30%,

Egyptian blue: mass percentoxygen � 43%

106. List an example of an element and a compound from Table 3.11.

Element—C and compound —Fe2O3

107. Is the process of charcoal production from the dry distillation of dry wood a chemical or physical change? Explain.

Chemical change. The composition of the dry wood changes into that of charcoal.

Standardized Test Practice pages 98–99

Sample

Mass of Chlorine

(g)

Mass of Fluorine

(g) % Cl % F

I 13.022 6.978 65.11 34.89

II 5.753 9.248 ? ?

Mass Analysis of Two Chlorine-Fluorine Samples

Multiple Choice 1. What are the values for % Cl and % F,

respectively, for Sample II?

a. 0.6220 and 61.65b. 61.65 and 38.35c. 38.35 and 0.6220d. 38.35 and 61.65

d

%Cl � 5.753 g

__ 5.753 g � 9.248 g

� 100 � 38.35%

%F � 9.248 g

__ 5.753 g � 9.248 g

� 100 � 61.65%

2. Which statement best describes the relationship between the two samples?

a. The compound in Sample I is the same as in Sample II. Therefore, the mass ratio of Cl to F in both samples will obey the law of definite proportions.

b. The compound in Sample I is the same as in Sample II. Therefore, the mass ratio of Cl to F in both samples will obey the law of multiple proportions.

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

, a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

, Inc

.



c. The compound in Sample I is not the same as in Sample II. Therefore, the mass ratio of Cl to F in both samples will obey the law of definite proportions.

d. The compound in Sample I is not the same as in Sample II. Therefore, the mass ratio of Cl to F in both samples will obey the law of multiple proportions.

d

3. After two elements react to completion in a closed container, the ratio of their masses in the container will be the same as before the reaction. Which law describes this principle?

a. law of definite proportionsb. law of multiple proportionsc. law of conservation of massd. law of conservation of energy

c

4. Which is NOT a physical property of table sugar?

a. forms solid crystals at room temperatureb. appears a white crystalsc. breaks down into carbon and water vapor

when heatedd. tastes sweet

c

5. Which describes a substance that is in the solid state?

a. Its particles can flow past one another.b. It can be compressed into a smaller volume.c. It takes the shape of its container.d. Its particles of matter are close together.

d

Use the diagram below to answer Questions 6 and 7.

A B C

6. Which best describes Figure A?

a. elementb. mixturec. solutiond. compound

d

7. Which statement is false?

a. Figure B is composed of two different compounds.

b. Figure C is composed of two different compounds.

c. Figure B represents 13 total atoms.d. Three different types of elements are

represented in Figure C.

b

8. Na, K, Li, and Cs all share similar chemical properties. In the periodic table of elements, they most likely belong to the same

a. row.b. period.c. group.d. element.

c

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

, a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

, Inc

.



9. Magnesium reacts explosively with oxygen to form magnesium oxide. Which is NOT true of this reaction?

a. The mass of magnesium oxide produced equals the mass of magnesium consumed plus the mass of oxygen consumed.

b. The reaction describes the formation of a new substance.

c. The product of the reaction, magnesium oxide, is a chemical compound.

d. Magnesium oxide has physical and chemical properties similar to both oxygen and magnesium.

d

Short Answer 10. Compare and contrast the independent variable

in an experiment with the dependent variable.

Both the independent and the dependent variables can have different values during the course of an experiment. The independent variable has specific values that are predetermined by the researcher, while the dependent variable has values that are measured as a result of the experiment and therefore cannot be determined in advance.

11. A student reports the melting point of a gas as �295°C. Explain why his claim is unlikely to be correct.

The value of −295°C is equivalent to −22 K. This answer does not make sense because 0 K is absolute zero and no temperature can be below this.

12. Place the following metric prefixes in order from the smallest value to the largest value: deci, kilo, centi, micro, mega, milli, giga, nano.

nano, micro, milli, centi, deci, kilo, mega, giga

Extended Response

Use the table below to answer Questions 13 to 15.

ItemSoluble

in Water?Soluble in Alcohol?

Density (g/c m 3 )

Particle Size (mm)

Sawdust no no 0.21 1

Mothball flakes

no yes 1.15 3

Table salt

yes no 2.17 2

Selected Properties of Substances in a Mixture

13. Is the mixture described in the table homo-geneous or heterogeneous? Explain how you can tell.

The mixture is heterogeneous. Based on particle size and color, the different substances can be readily distinguished.

14. Do the data describe chemical or physical prop-erties? Explain your answer.

These are physical properties because they depend only on the substance itself. Chemical properties depend on the behavior of substances as they react with other substances.

15. Propose a method to separate the three substances based on the properties described above.

Use the solubility of mothballs in alcohol first: dissolve the mothballs and filter or decant the liquid. Use crystallization to remove the alcohol. Next, add water to the remaining substances: the sawdust will float since its density is less than that of water, and the salt will dissolve. Filter or decant to separate the two substances. Crystallize the salt to remove the water.

Cop

yrig

ht ©

Gle

ncoe

/McG

raw

-Hill

, a d

ivis

ion

of T

he M

cGra

w-H

ill C

ompa

nies

, Inc

.



16. Explain the difference between a chemical change and a physical change. Is the combus-tion of gasoline a chemical change or a physical change? Explain your answer.

A physical change does not change the composition of the substance, whereas a chemical change is a process in which one or more substances are changed into new substances. The combustion of gasoline is a chemical change because the gasoline is changed into other substances during combustion.

SAT Subject Test: Chemistry 17. Which is a correct statement about methods for

separating mixtures?

a. Distillation results in the formation of solid particles of a dissolved substance.

b. Filtration depends on differences in sizes of particles.

c. Separations depend on the chemical properties of the substances involved.

d. Chromatography depends on the different boiling points of substances.

e. Sublimation can be used to separate two gases present in a mixture.

b

Use the table below to answer Questions 18 and 19.

Compound % H % C % O

Carbonic acid ( H 2 C O 3 ) 3.2 19.4 77.4

Acetic acid (C H 3 COOH) 6.7 40.0 53.3

Methanol (C H 3 OH) 12.5 37.5 40.0

Methanal ( H 2 CO) 6.7 40.0 53.3

Isopropanol ( C 3 H 8 O) 13.3 60.0 26.7

Percent by Mass of Carbon, Hydrogen, and Oxygen in Selected Compounds

18. You have a 125-g sample of one of these substances. You determine that it is made of 16.7 g H, 75.0 g C, and 33.0 g O. Which compound is it?

a. acetic acidb. carbonic acidc. methanald. methanole. isopropanol

e

19. In another experiment, you determine that a sample of acetic acid consists of 56.8% oxygen. What is your percent error?

a. 3.50%b. 6.57%c. 1.07%d. 12.6%e. 2.06%

b

matter—properties and changesmatter—properties and...

Documents