Chapter 10

Chapter 10Chemical Quantities

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1. StatementChemistry is a quantitative science.

2. What is one way to measure matter?One way to measure matter is to count how many of something you have.

3. StatementKnowing how the count, mass, and volume of an item relate to a common unit allows you to convert among these units.

This is called Dimensional Analysis.

Chapter 10.1 The Mole:A Measurement of Matter

Sample Problem 10.1What is the mass of 90 average-size apples if 1 dozen of the apples has a mass of 2.0 Kg?(15 Kg)Do the problems 1 and 2 at the bottom of page 307.

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1. How do chemists count the number of atoms, molecules, or formula units in a substance?

The chemists use a unit that is a specified number of particles. The unit is called the mole.

2. What is a mole?It represents 6.02 x 1023 particles of that substance. It is the SI unit for measuring the amount of a substance.

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3. What is the name of number of representative particles in a mole?It is called Avogadro’s number.It was named in honor of the Italian scientist Amedeo Avogadro di Quaregna, who helped clarify the difference between atoms and molecules.

4. What does the term representative particle mean?It refers to the species present in a substance, usually atoms, molecules, or formula units.

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5. StatementThe mole allows chemists to count the number of representative particles in a substance.

6. Converting between Number of Particles and Moles1 mole = 6.02 x 1023 particles


Sample Problem 10.2Converting Number of Atoms to MolesMagnesium is a light metal used in the manufacture of aircraft, automobile wheels, and tools. How many moles of magnesium is 1.25 x 1023 atoms of magnesium?Do Problems 3 and 4 at the bottom of Page 309.


Sample Problem 10.3Converting Moles to Number of AtomsPropane is a gas used for cooking and heating. How many atoms are in 2.12 moles of propane (C3H8)?

Do problems 5 and 6 at the bottom of page 311.

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1. What is Molar Mass?It is the mass of a mole of a substance.

2. How do you determine the molar mass of an element and of a compound?The atomic mass of an element expressed in grams on the Periodic table.

To Calculate the molar mass of a compound, do the following chart:

Symbol Subscript

Atomic Mass

Total Mass


Sample Problem 10.4Finding the Molar Mass of a CompoundThe decomposition of hydrogen peroxide (H2O2) provides sufficient energy to launch a rocket. What is the molar mass of hydrogen peroxide?Do problems 7 and 8 at the bottom of page 315.


10.1 Lesson CheckDo the following problems: 12, 13, 14, 15

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1. How do you convert the mass of a substance to the number of moles of the substance?

Use the molar mass of an element or compound to convert between the mass of a substance and the moles of the substance.

Chapter 10.2 Mole-Mass and Mole-Volume Relationships

Sample Problem 10.5Converting Moles to massItems made out of aluminum are resistant to corrosion because of the aluminum reacts with oxygen in the air to form a coating of aluminum oxide (AL2O3). This tough, resistant coating prevents any further corrosion. What is the mass, in grams, of 9.45 mole of aluminum oxide?Do Problems 16 and 17 at the bottom of page 318.


Sample Problem 10.6Converting Mass to MolesWhen iron is exposed to air, it corrodes to form red-brown rust. Rust is iron (III) oxide (Fe2O3). How many moles of iron (III) oxide are contained in 92.2 grams of pure Fe2O3?


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1. What is Avogadro’s Hypothesis?It states that equal volumes of gases at the same temperature and pressure contain equal numbers of particles.2. What is STP? It is standard temperature and pressure. The temperature is 0°C. Pressure is 101.3 kPa or 1 atmosphere (atm).

3. What is molar volume? 22.4 L


Sample Problem 10.7Calculating Gas Quantities at STPSulfur dioxide (SO2) is a gas produced by burning coal. It is an air pollutant and one of the causes of acid rain. Determine the volume, in liters, of 0.60 mole SO2 at STP.



Sample problem 10.8Calculating the Molar Mass of a Gas at STPThe density of a gaseous compound containing carbon and oxygen is found to be 1.964 g/L at STP. What is the molar mass of the compound?




10.2 lesson CheckDo the following problems: 26, 27, 28, 29, 30, and 31.

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1. What is percent composition?It is the relative amounts of the elements in a compound.2. How do you calculate the percent composition of a compound?The percent by mass of an element in a compound is the number of grams of the element divided by the mass in grams of the compound, multiplied by 100%.

Chap 10.3 Percent Composition & Chemical Formula

Sample Problem 10.9Calculating Percent Composition from Mass DataWhen a 13.60-g sample of a compound containing only magnesium and oxygen is decomposed, 5.40 grams of oxygen is obtained. What is the percent composition of this compound?Do problems 33 and 34 at the bottom of page 326.


Sample Problem 10.10Calculating Percent Composition from a FormulaPropane (C3H8), the fuel commonly used in gas grills, is one of the compounds obtained from petroleum. Calculate the percent composition of propane.Do problems 35 and 36 at the bottom of page 327.


Sample Problem 10.11Calculating the Mass of an Element in a Compound Using Percent Composition.Calculate the mass of carbon and the mass of hydrogen in 82.0 grams of propane (C3H8).


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1. What is the empirical formula of a compound?

It gives the lowest whole-number ratio of the atoms or moles of the elements in a compound.2. How can you calculate the empirical formula of a compound?


Sample Problem 10.12Determining the Empirical Formula of a CompoundA compound is analyzed and found to contain 25.9% nitrogen and 74.1% oxygen. What is the empirical formula of the compound?Do problems 39 and 40 at the bottom of page 331.

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1. What is the molecular formula of a compound?

It is a simple whole-number multiple of its empirical formula.It can be same as its experimentally determined empirical formula.


Sample problem 10.13Finding the Molecular Formula of a CompoundCalculate the molecular formula of a compound whose molar mass is 60.0 g/mole and empirical formula is CH4N.



10.3 Lesson CheckDo the following problems: 46, 47, and 48.

Chapter 10 Study Guide

Study Guide on Page 336Math Tune-Up: Mole Problems on Page 337

Chapter 10 Assessment

Lesson by Lesson on pages 338-342

Chapter 10 Test

Test on Chapter 10 Chemical Quantities

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Chapter 10