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Name:___________________________________________Period:______Date:____________

THE MOLE (a counting unit)……….Again!

A mole represents a______________________________, much in the same way that a dozen represents a set of twelve.

1 dozen eggs = 12 eggs; 1 mol eggs = 6.022 × 1023 eggs

1 dozen carbon atoms = 12 carbon atoms; 1 mol carbon atoms = 6.022 × 1023 carbon atoms

The number “6.022 × 1023 ” is known as “___________________________________”.

If you write out Avogadro’s number, it looks like this: 602,200,000,000,000,000,000,000

Remember:

1 mole of atoms = 6.02 × 1023 atoms

1 mole of molecules = 6.02 × 1023 molecules

1 mole of formula units = 6.02 × 1023 formula units

1 mole of ions = 6.02 × 1023 ions

Atomic Mass vs. Molar Mass:

__________________________= the mass of ONE ATOM expressed in atomic mass units (amu) o Ex: Oxygen’ s atomic mass = 15.999 amu; this is the average mass of ____ oxygen atom

___________________________= the mass of ONE MOLE of atoms, molecules, or formula units expressed in grams o Ex: Oxygen’s molar mass = 15.999 g; this is the mass of _______________ oxygen atoms

Atomic Mass vs. Molar Mass

Element & Symbol Atomic Mass—Average mass of 1 Atom

Molar Mass—Mass of 1 mole of atoms (6.02 X 1023 atoms)

Carbon (C) 12.0 amu

Helium (He) 4.00 amu

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ACIDS: You need to know these!

Hydrochloric Acid = ____________ Nitric Acid =_________________ Sulfuric Acid =_______________ Carbonic Acid = _________________ Phosphoric Acid =_____________ Acetic Acid = _____________________

I. CALCULATING MOLAR MASS: • Find the molar mass of each of the following compounds: 1. Phosphoric Acid 2. Calcium Nitrate 3. Iron (III) Carbonate

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• Find the molar mass for the following compounds: 1) sulfuric acid 2) iron (II) bromide 3) manganese(II) phosphate 4) diphosphorous pentoxide • Answer the following questions based on your notes. 5) ___________________________ is the mass of ONE MOLE of atoms, molecules, or formula

units expressed in ___________________

6) _________________________ is the mass of ONE ATOM expressed in _______________

7) What is the numeric value of “the mole”? ______________________________

8) What does the mole measure? _______________________________________

9) The mole is also referred to as ____________________________ number.

Molar Mass Homework #1-9 Below

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II. FINDING PERCENT COMPOSITION:

• ____________________________= is the percent by mass of each element in the compound. The percent composition is ______________the same regardless of the size of the sample.

• Ex: H20 is ALWAYS 11.2 % hydrogen and 88.8% oxygen (by mass) The percent composition of the elements in a compound adds up to _______.

• Formula Used: Molar Mass of the element in a compound Total Molar Mass of the compound Or think of it as: Part _ Whole

Steps: 1. Find molar mass of each element (parts) 2. Find the total molar mass of the compound (whole) 3. Part

Whole 4. Evaluate your answer (percentages should add to approximately 100%)

Ex: Find the percent composition of aluminum sulfate. NOTE: Therefore, a 100g sample of Al2(SO4)3 would contain ________g Al, _______g S, and _________g O

X 100

X 100

X 100

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1. Find the percent composition of magnesium hydroxide. 2. Find the percent composition of calcium cyanide. 3. Find the percent composition of nickel (II) iodide. 4. Find the percent composition of copper (I) sulfide.

% Composition Homework: # 1-4 Below

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III. CONVERSIONS BETWEEN GRAMS & MOLES o KEY IDEA: It is important to know the following conversion: The molar mass of a compound or the

mass an element is equal to 1 mole of that compound or element. Ex: 1 mole of carbon is equal to 12 grams of carbon! Ex: ______________of water is equal to ______________(molar mass) of water

o Use a T-chart to convert from what you know to what you do not know. Use your conversion factors so ________________cancel out!

Ex #1: How many moles are represented by 11.5 g of magnesium hydroxide?

Ex #2: How many grams of aluminum sulfide are present in 0.44 moles of aluminum sulfide?

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1. How many grams of barium cyanide are present in 0.638 moles of barium cyanide? 2. How many moles of calcium bromide are present in 50.4 grams of calcium bromide? 3. How many grams of calcium hydroxide are present in 1.26 moles of calcium hydroxide? 4. How many moles of acetic acid are present in 86.2 grams of acetic acid?

Grams & Moles Conversion Homework = #1-4 Below

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IV. CALCULATION of FORMULAS: • 2 types of formulas:

1. _____________________________________ (M.F.) = shows the types and numbers of atoms combined in a single molecule.

o Ex: C6H12O6 (glucose)

Actually has 24 atoms!

2. ______________________________________ (E.F.) = a chemical formula showing the simplest whole number ratio of atoms in a compound.

o Ex: Reduce glucose C6H12O6 by dividing all the subscripts by 6 – the empirical formula would be _________________

o In the chart below, fill in the empirical formula given the molecular formula:

o Notice 2 things:

1. Some molecular formulas ___________ be reduced (H2O)

2. Several compounds can _______________the same E.F., but each

compound has its own _________________molecular formula

• WHY DO WE USE THE EMPIRICAL FORMULA IF IT CONTAINS LESS INFORMATION? It is easier to experimentally determine the empirical formula of a compound than the molecular formula. So the E.F. is usually found 1st as a step towards finding the molecular formula.

Molecular Formula Empirical Formula

H2O2

H2O

C8H16

C2H4

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• Steps to finding an EMPIRICAL FORMULA: 1. The amount of each element should be listed in grams. If analysis of the compound is in

percent, convert to grams: assume a 100 g sample of the compound. 2. Convert grams of EACH element to moles (T-chart).

3. Divide moles of each element by the smallest number of moles.

4. Round each answer from “3” to the nearest whole number and write the empirical formula using these numbers as subscripts.

* NOTE: ROUND ALL NUMBERS to 0.001

Ex #1: What is the empirical formula for a compound if a sample contains 0.9g of calcium and 1.6g of chlorine?

Ex # 2: What is the empirical formula for a compound that is 40% C, 6.71% H, and 53.3% O?

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1. Calculate the empirical formula of a compound that contains 1.67g of cerium, Ce, and 4.54g of iodine, I.

2. 2-Methylpropene is a compound used to make synthetic rubber. A sample of 2-methylpropene contains 0.566g C and 0.0933g H. Determine its empirical formula. 3. Determine the empirical formula of a compound containing 63.50% silver, 8.25% nitrogen, and 28.25% oxygen. 4. Freons are gaseous compounds used in refrigeration. A particular freon contains 9.93% C, 58.6% Cl, and 31.4% F by mass. What is the empirical formula of this freon?

Empirical Formula Homework: #1-4 Below

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• Steps to finding a MOLECULAR FORMULA 1. If it is not given, determine the empirical formula of the compound. (Follow all steps

necessary to determine an empirical formula)

2. Calculate molar mass of the empirical formula.

3. Divide the molar mass of the _____________________by the molar mass determined from the___________________________________.

4. Round the answer to “3” to the nearest whole number and multiply all subscripts in the

empirical formula by this number. Ex #1: What is the molecular formula of a substance that has an empirical formula of AgCO2 and a molar mass of 304g/mol?

Ex #2: An unknown compound contains 85.64% carbon and 14.36% hydrogen. It has a molar mass of 42.08 g/mol. Find its molecular formula.

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1. The molar mass of benzene, an important industrial solvent, is 78.0g/mol and its empirical formula is CH. What is the molecular formula for benzene? 2. What is the molecular formula of dichloroacetic acid, if the empirical formula is CHOCl and the molar mass of the acid is 129g/mol? 3. A compound used as an additive for gasoline to help prevent engine knock, shows the following percentage composition: 24.27% C, 4.07% H, and 71.65% Cl. The molar mass is known to be 98.96 g/mol. Determine the empirical formula and the molecular formula for this compound.

Molecular Formula Homework: #1-7 Below

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4. Suppose a sample of cyclohexane contains 4.282 g of carbon and 0.718 g of hydrogen. The molar mass of cyclohexane is 84.2 g/mol. Determine the molecular formula. • Answer the following questions based on your notes.

5. The _____________________________________specifies the actual number of atoms of each element in

one molecule or formula unit of the substance.

6. The _____________________________________ for a compound is the formula with the smallest whole-

number ratio between elements.

7. What is the empirical formula for C10H8? __________________

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copper II sulfate pentahydrate CuSO4● 5H2O

V. HYDRATES: • Suppose an ionic substance is dissolved in water. The water can be

evaporated to leave the solid ionic compound. SOME ionic compounds, however, will form solid crystals that incorporate ________________________(where the water molecules are weakly attracted to the ions in the crystal structure).

• __________________________= an ionic compound containing water molecules incorporated into its solid crystal structure

o In other words, a hydrate is a collection of ________________(negative ions),

_____________________(positive ions), and _____________________________

• _________________________________= the ionic compound that remains after the water has been removed (usually by heating) from the hydrate

o Note: salt = ionic compound (usually an ionic compound that does not contain OH − ions)

• The heating of a hydrate to produce an anhydrous salt can be illustrated as follows:

hydrate + heat → anhydrous salt + water

• Naming Hydrates & Writing Hydrate Formulas:

o Prefixes are used as coefficients in the following manner in the chemical formulas for hydrates.

o The chemical formula for magnesium sulfate heptahydrate is ______________________

7 moles of H2O are associated with every 1 mole of MgSO4.

o The chemical formula for zinc sulfate dihydrate is _____________________________ 2 moles of H2O are associated with every 1 mole of ZnSO4.

o What is the name of the following hydrate, FePO4 • 4H2O?

__________________________________________________________________

MOLAR MASS OF HYDRATES: • When determining the molar mass of a hydrate, the molar mass of the associated water must be

included. EX #1: Calculate the molar mass of calcium sulfate dihydrate.

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PERCENT COMPOSITION of HYDRATES: Steps:

1. Find molar mass of water. 2. Find the molar mass of the salt. 3. Add the mass of the water and the salt in order to get the total mass of the hydrate. 4. Mass of Water (part) __

Mass of Hydrate (whole)

Ex: What percentage of water is found in sodium sulfide nonahydrate? EMPIRICAL FORMULA of a HYDRATE:

Steps: 1. Identify what you know and what you do not know.

2. All amounts should be listed in grams. If analysis is in percent, convert to grams: assume a 100 g sample.

3. Convert grams of anhydrous salt to moles.

4. Convert grams of water to moles.

5. Divide moles by the smallest number of moles.

6. Round each answer from “5” to the nearest whole number and these numbers become the COEFFICIENTS for the salt and water.

Ex: Suppose a hydrate contains 9.520 g barium iodide and 0.887g water. Determine the formula of the hydrate.

X 100

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1. Determine the percentage of water in copper (II) sulfate pentahydrate. 2. Suppose a hydrate contains 0.391g Li2SiF6 and 0.0903g H20. Determine the formula of the hydrate. 3. Determine the percentage of water in sodium carbonate monohydrate.

Hydrate Homework: #1-12

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4. Suppose a hydrate contains 0.737g magnesium sulfate and 0.736g water. Determine the formula of the hydrate. 5. Suppose a hydrate contains 76.9% calcium sulfite and 23.1% water. Determine the formula of the hydrate. 6. Suppose a hydrate contains 89.2% barium bromide and 10.8% water. Determine the formula of the hydrate.

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7. The ____________________________ salt is the ionic compound that remains after the water has been

removed from the hydrate.

8. A _______________________ is an ionic compound containing water molecules incorporated into its solid crystal structure.

9. How can water molecules be removed from a hydrate? 10. What is the formula for nickel II chloride hexahydrate? ______________________________ 11. How many water molecules are present in the following hydrate: nickel II chloride hexahydrate? _______

12. Write the name of the following compound: MgCO3 • 5H20 _________________________________

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THE MOLE & MATH REVIEW WORKSHEET

1) Calculate the molar mass for the following: a) Aluminum sulfate

b) Ammonium phosphate

2) Convert: a) 6.38 moles of iron (II) phosphate to g

b) 5.49 moles of potassium iodide to g

c) 188 g calcium hydroxide to moles

d) 84.2 g potassium phosphate to moles

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3) Find the percent composition of zinc hydroxide.

4) Determine the percent of water in sodium sulfate decahydrate.

5) Determine the empirical formulas for the following two compounds that were analyzed and found to contain the following:

a) 3.30 g magnesium, 21.7 g bromine

b) 40.23% potassium, 26.95% chromium, 32.81% oxygen

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6) A compound of aluminum and chlorine is composed of 9.00 g of aluminum for every 35.5 g of chlorine. The molar mass of this compound is 267 g/mol. Determine the empirical formula and the molecular formula.

7) A compound with a molar mass of 180.15 g/mol is found to be 40.00% carbon, 6.71% H, and 53.28% oxygen. Determine the empirical formula and the molecular formula of the compound.

8) What is the formula for a hydrate that is 90.7% strontium oxalate and 9.30% water?

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9) What is the formula for a hydrate that is 433.5 grams of Mo2S5 and 66.5 grams of H2O?

10) The _________________________________ is the mass of one mole of atoms, molecules, or formula units and is expressed in ____________________________________.

11) The __________________specifies the actual number of atoms of each element in one molecule or formula

unit of the substance.

12) ______________________________ is the numeric value of “the mole”.

13) The ____________________________ salt is the ionic compound that remains after the water has been removed from the hydrate.

14) The ______________________ is the mass of one atom and is expressed in _______________________.

15) The ______________________ for a compound is the formula with the smallest whole-number ratio between elements.

16) What does the mole measure?______________________________________________________

17) A _____________________ is an ionic solid with trapped water molecules.

18) What is the empirical formula for C6H8O6? _____________________________

19) The mole is also referred to as _____________________________ number.

20) How many water molecules are present in the following hydrate: barium hydroxide octahydrate? ___

21) Write the formulas for the following acids: a) Carbonic acid ___________________________________ b) Sulfuric acid ___________________________________ c) Phosphoric acid ___________________________________ d) Nitric acid ___________________________________ e) Acetic acid ___________________________________ f) Hydrochloric acid ___________________________________

22) What is the formula for sodium acetate trihydrate? ______________________________

23) Write the name of the following compound: CoCl2 • 6H20 _________________________________

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Unit Learning Map (11 days): Mole & Math Mrs. Hostetter

Class: Academic Chemistry A - Grade 11

Unit Essential Question(s): Optional Instructional Tools:

Guided Notes Lab Materials:

Chalk Lab MgO Lab Hydrate Lab

How do you analyze and solve chemistry math

problems?

Molar mass Percent composition Conversions Empirical and molecular formulas

How is molar mass determined?

How is percent composition determined?

How are molar mass and Avogadro’s number used in conversion?

How are empirical and molecular formulas determined?

Mole Atomic mass Formula mass Molar mass

Percent composition

Molar mass Avogadro’s number

Empirical formula Molecular formula Hydrate Anhydrous

Vocabulary: Vocabulary: Vocabulary: Vocabulary:

Lesson Essential Questions: Lesson Essential Questions: Lesson Essential Questions: Lesson Essential Questions:

Concept Concept Concept Concept

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Math & Moles Vocabulary:

1) Mole = unit of measurement for an amount of a something; a counting unit

2) Atomic mass = the mass of one atom expressed in atomic mass units

3) Molar mass = the mass of one mole of atoms, molecules, or formula units expressed in grams

4) Percent Composition = is the percent by mass of each element in the compound

Steps:

1. Find molar mass of each element (parts)

2. Find the total molar mass of the compound (whole)

3. Part Whole

4. Evaluate your answer (percentages should add to approximately 100%) 5) Avagadro’s number = 6.022 x 1023

6) Molecular formula (M.F.) = shows the types and numbers of atoms combined in a single molecule

Steps to finding a MOLECULAR FORMULA 1. If it is not given, determine the empirical formula of the compound. (Follow all steps

necessary to determine an empirical formula) 2. Calculate molar mass of the empirical formula. 3. Divide the molar mass of the compound by the molar mass determined from the empirical

formula. 4. Round the answer to “3” to the nearest whole number and multiply all subscripts in the

empirical formula by this number.

7) Empirical formula (E.F.) = a chemical formula showing the simplest whole number ratio of atoms in a compound

• Steps to finding an EMPIRICAL FORMULA: 1. The amount of each element should be listed in grams. If analysis of the compound is in

percent, convert to grams: assume a 100 g sample of the compound. 2. Convert grams of EACH element to moles (T-chart).

3. Divide moles of each element by the smallest number of moles.

4. Round each answer from “3” to the nearest whole number and write the empirical formula using these numbers as subscripts.

8) Hydrate = an ionic compound containing water molecules incorporated into its solid crystal structure

9) Anhydrous salt = the ionic compound that remains after the water has been removed (usually by heating) from the hydrate

ACIDS: You need to know these!

Hydrochloric Acid = HCl Nitric Acid = HNO3 Phosphoric Acid = H3PO4

Sulfuric Acid = H2SO4 Carbonic Acid = H2CO3 Acetic Acid = CH3COOH

X 100