1. CHEMISTRY Matter and Change
Chapter 13: Gases

2. Table Of Contents Section 13.1 The Gas Laws
CHAPTER13
Table Of Contents
Section The Gas Laws
Section The Ideal Gas Law
Section Gas Stoichiometry
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3. SECTION13.1
The Gas Laws
State the relationships among pressure, temperature, and volume of a constant amount of gas.
Apply the gas laws to problems involving the pressure, temperature, and volume of a constant amount of gas.
scientific law: describes a relationship in nature that is supported by many experiments

4. The Gas Laws Boyle’s law absolute zero Charles’s law Gay-Lussac’s law
SECTION13.1
The Gas Laws
Boyle’s law
absolute zero
Charles’s law
Gay-Lussac’s law
combined gas law
For a fixed amount of gas, a change in one variable—pressure, temperature, or volume—affects the other two.

5. P1V1 = P2V2 where P = pressure and V = volume
SECTION13.1
The Gas Laws
Boyle's Law
Boyle’s law *
P1V1 = P2V2 where P = pressure and V = volume

6. The Gas Laws Charles's Law
SECTION13.1
The Gas Laws
Charles's Law
As temperature increases, so does the volume of gas when the amount of gas and pressure do not change.
Kinetic-molecular theory explains this property.

7. SECTION13.1
The Gas Laws
Charles's Law (cont.)

8. The Gas Laws Charles's Law (cont.) Absolute zero *. Charles’s law *
SECTION13.1
The Gas Laws
Charles's Law (cont.)
Absolute zero *.
Charles’s law *

9. SECTION13.1
The Gas Laws
Gay-Lussac's Law
Gay-Lussac’s law *

10. Gay-Lussac's Law (cont.)
SECTION13.1
The Gas Laws
Gay-Lussac's Law (cont.)

11. SECTION13.1
The Gas Laws
The Combined Gas Law
The combined gas law *.

12. The Combined Gas Law (cont.)
SECTION13.1
The Gas Laws
The Combined Gas Law (cont.)

13. SECTION13.2
The Ideal Gas Law
Relate number of particles and volume using Avogadro’s principle.
Relate the amount of gas present to its pressure, temperature, and volume using the ideal gas law.
Compare the properties of real and ideal gases.
mole: an SI base unit used to measure the amount of a substance; the amount of a pure substance that contains 6.02 × 1023 representative particles

14. The Ideal Gas Law Avogadro’s principle molar volume
SECTION13.2
The Ideal Gas Law
Avogadro’s principle
molar volume
ideal gas constant (R)
ideal gas law
The ideal gas law relates the number of particles to pressure, temperature, and volume.

15. The Ideal Gas Law Avogadro's Principle Avogadro’s principle *
SECTION13.2
The Ideal Gas Law
Avogadro's Principle
Avogadro’s principle *

16. Avogadro's Principle (cont.)
SECTION13.2
The Ideal Gas Law
Avogadro's Principle (cont.)
The molar volume of a gas is the volume 1 mol occupies at 0.00°C and 1.00 atm of pressure.
0.00°C and 1.00 atm are called standard temperature and pressure (STP).
At STP, 1 mol of gas occupies 22.4 L.

17. The Ideal Gas Law The Ideal Gas Law
SECTION13.2
The Ideal Gas Law
The Ideal Gas Law
Ideal gas particles occupy a negligible volume and are far enough apart to exert minimal attractive or repulsive forces on each other.
Combined gas law to ideal gas law

18. The Ideal Gas Law (cont.)
SECTION13.2
The Ideal Gas Law
The Ideal Gas Law (cont.)
The ideal gas constant is represented by R and is L•atm/mol•K when pressure is in atmospheres.
The ideal gas law *

19. The Ideal Gas Law (cont.)
SECTION13.2
The Ideal Gas Law
The Ideal Gas Law (cont.)

20. The Ideal Gas Law—Molar Mass and Density
SECTION13.2
The Ideal Gas Law
The Ideal Gas Law—Molar Mass and Density
Molar mass and the ideal gas law

21. The Ideal Gas Law—Molar Mass and Density (cont.)
SECTION13.2
The Ideal Gas Law
The Ideal Gas Law—Molar Mass and Density (cont.)
Density and the ideal gas law

22. Real Versus Ideal Gases
SECTION13.2
The Ideal Gas Law
Real Versus Ideal Gases
Ideal gases follow the assumptions of the kinetic-molecular theory.
Characteristics of ideal gases:
There are no intermolecular attractive or repulsive forces between particles or with their containers.
The particles are in constant random motion.
Collisions are perfectly elastic.
No gas is truly ideal, but most behave as ideal gases at a wide range of temperatures and pressures.

23. Real Versus Ideal Gases (cont.)
SECTION13.2
The Ideal Gas Law
Real Versus Ideal Gases (cont.)
Real gases *.
Polar molecules have larger attractive forces between particles.
Polar gases do not behave as ideal gases.
Large nonpolar gas particles occupy more space and deviate more from ideal gases.

24. SECTION13.3
Gas Stoichiometry
Determine volume ratios for gaseous reactants and products by using coefficients from chemical equations.
Apply gas laws to calculate amounts of gaseous reactants and products in a chemical reaction.
coefficient: the number written in front of a reactant or product in a chemical equation, which tells the smallest number of particles of the substance involved in the reaction
When gases react, the coefficients in the balanced chemical equation represent both molar amounts and relative volumes.

25. Stoichiometry of Reactions Involving Gases
SECTION13.3
Gas Stoichiometry
Stoichiometry of Reactions Involving Gases
The gas laws can be applied to calculate the stoichiometry of reactions in which gases are reactants or products.
2H2(g) + O2(g) → 2H2O(g)
2 mol H2 reacts with 1 mol O2 to produce 2 mol water vapor.

26. Stoichiometry and Volume-Volume Problems
SECTION13.3
Gas Stoichiometry
Stoichiometry and Volume-Volume Problems
Coefficients in a balanced equation represent volume ratios for gases.

27. Stoichiometry and Volume-Mass Problems
SECTION13.3
Gas Stoichiometry
Stoichiometry and Volume-Mass Problems
A balanced chemical equation allows you to find ratios for only moles and gas volumes, not for masses.
All masses given must be converted to moles or volumes before being used as part of a ratio.

28. The Gas Laws Key Concepts
SECTION13.1
The Gas Laws
Study Guide
Key Concepts
Boyle’s law states that the volume of a fixed amount of gas is inversely proportional to its pressure at constant temperature.
P1V1 = P2V2
Charles’s law states that the volume of a fixed amount of gas is directly proportional to its kelvin temperature at constant pressure.

29. The Gas Laws Key Concepts
SECTION13.1
The Gas Laws
Study Guide
Key Concepts
Gay-Lussac’s law states that the pressure of a fixed amount of gas is directly proportional to its kelvin temperature at constant volume.
The combined gas law relates pressure, temperature, and volume in a single statement.

30. The Ideal Gas Law Key Concepts
SECTION13.2
The Ideal Gas Law
Study Guide
Key Concepts
Avogadro’s principle states that equal volumes of gases at the same pressure and temperature contain equal numbers of particles.
The ideal gas law relates the amount of a gas present to its pressure, temperature, and volume PV = nRT

31. The Ideal Gas Law Key Concepts
SECTION13.2
The Ideal Gas Law
Study Guide
Key Concepts
The ideal gas law can be used to find molar mass if the mass of the gas is known, or the density of the gas if its molar mass is known.
At very high pressures and very low temperatures, real gases behave differently than ideal gases.

32. Gas Stoichiometry Key Concepts
SECTION13.3
Gas Stoichiometry
Study Guide
Key Concepts
The coefficients in a balanced chemical equation specify volume ratios for gaseous reactants and products.
The gas laws can be used along with balanced chemical equations to calculate the amount of a gaseous reactant or product in a reaction.