Gases Chapter 10/11 Modern Chemistry

Chapter 8 Section 1 Describing Chemical Reactions p. 261-275

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GasesChapter 10/11Modern Chemistry

Sections 10.1, 11.1-11.3Sections 10.1, 11.1-11.3The Kinetic Molecular Theory of MatterThe Kinetic Molecular Theory of Matter

Gases and PressureGases and PressureThe Gas LawsThe Gas Laws

Gas Volumes and the Ideal Gas LawGas Volumes and the Ideal Gas Law

Chapter 11 Section 3 Ideal Gas Law p. 378-385

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Gas Volumes and the Ideal Gas Law

Section 11.3Section 11.3


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Gay-Lussac’s Law of Combining Volumes of Gas“At constant temperature and pressure, the volumes of gaseous reactants and products can be expressed as ratios of small whole numbers.”

H2 (g) + O2 (g) H2O (g)

2L 1L 2LThis could be any volume units.

Law of Combining VolumesLaw of Combining Volumes


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Avogadro’s LawAvogadro’s Law“Equal volumes of gases at the same temperature and pressure contain equal numbers of molecules.”

2H2 (g) + O2 (g) 2H2O (g)

2 molecules 1 molecule 2 molecules

2 moles 1 mole 2moles 2 volumes 1 volume 2 volumes


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Same volume – Same number of particlesThe type of gas doesn’t affect this relationship.At STP, one mole of any gas occupies 22.4 L.

Avogadro’s LawAvogadro’s Law


9p. 379Mola

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The volume occupied by one mole of gas at STP is know as the standard molar volume of a gas.

22.41410 L / 1 mole

22.4 L / mole

Molar Volume of a GasMolar Volume of a Gas


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a. What volume does 0.0685 mol of gas occupy at STP?

b. What quantity of gas, in moles, is contained in 2.21 L at STP?

p. 3

81

1. 0.0987 mol

Molar Volume ProblemsMolar Volume Problems


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1. At STP, what is the volume of 7.08 mol of nitrogen gas?

2. A sample of hydrogen gas occupies 14.1 L at STP. How many moles of the gas are present?

p. 3

81

1.159 L N2

2.2. 0.629 mol H2

Practice Problems p. 381Practice Problems p. 381


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For a one mole sample of gasM = molar mass = ________ gV = molar volume = 22.4 L

Density of Gases at STPDensity of Gases at STP

D=M

V

44.01 g CO2 22.4 L CO2

= = 1.799 g/L CO2


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1. What is the density of C3H8 gas at STP?

1. 1.9684 g/L

Gas Density ProblemGas Density Problem


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1. What is the density of nitrogen gas at STP?

2. What is the density of CH4 gas at STP?

1. 1.251 g/L 2. 0.7156 g/L

Practice ProblemsPractice Problems

Great News! We’ve bred a cow that doesn’t release any methane.


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• “The mathematical relationship among pressure, volume, temperature and the number of moles of a gas”

• Nothing is held constant; one set of conditions.

P V = n R T

Ideal Gas LawIdeal Gas Law

atmkPammHg

litersmoles

constant

Kelvin


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Boyle’s LawCharles Law

Gay-Lussac’s Law

Ideal Gas LawIdeal Gas Law


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Ideal G

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1. What is the pressure in atmospheres exerted by a 0.500 mol sample of nitrogen gas in a 10.0 L container at 298 K?

p. 3

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1. 1.22 atm

Ideal Gas Law ProblemsIdeal Gas Law Problems


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An unknown gas has a density of 0.0262 g/mL at a pressure of 0.918 atm and a temperature of 10.°C. What is the molar mass of the gas?

p. 8

98 #

289

663 g/mol

Ideal Gas Law ProblemsIdeal Gas Law Problems


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1. What pressure, in atmospheres, is exerted by 0.325 mol of hydrogen gas in a 4.08 L container at 35°C?

2. A gas sample occupies 8.77 L at 20°C.What is the pressure, in atmospheres, given that there are 1.45 mol of gas in the sample?

p. 3

85

1. 2.01 atm 2. 3.98 atm

Practice Problems p. 385Practice Problems p. 385


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• Three new “tools”– Law of Combining Gas Volumes

•Use the coefficients (works with gases only)

– Molar volume• 22.4 L / 1 mole (works at STP only!)

– Ideal Gas Law• PV = nRT•A way to convert from moles to liters if the conditions are not STP

Gas StoichiometryGas Stoichiometry


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1. Propane, C3H8, is a gas that is sometimes used as a fuel for cooking and heating. C3H8(g) + 5O2(g) → 3CO2(g) + 4H2O(g)

(a)What will be the volume, in liters, of oxygen required for the complete combustion of 0.350 L of propane?

(b)What will be the volume of carbon dioxide produced in the reaction? Assume that all volume measurements are made at the same temperature and pressure.

Gas StoichiometryGas Stoichiometry

1. (a) 1.75 L O2 (b) 1.05 L CO2

p. 3

82


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1. Assuming all volume measurements are made at the same temperature and pressure, what volume of hydrogen gas is needed to react completely with 4.55 L of oxygen gas to produce water vapor?

1. 9.10 L H2

Gas Stoichiometry ProblemGas Stoichiometry Problemp.

382


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Zinc and hydrochloric acid react to produce hydrogen gas. If 5.00 grams of zinc is reacted with excess acid at STP, how many liters of gas will be produced?

1.71 liters

Gas Stoichiometry ProblemGas Stoichiometry Problem


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Baking soda and vinegar react to produce carbon dioxide gas. If 17.0 grams of baking soda are reacted with excess vinegar, how many liters of carbon dioxide will be produced at STP?

NaHCO3 (aq)+ HC2H3O2 (aq) CO2 (g)+ H2O (l)+ NaC2H3O2 (aq)

4.53 L



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In the decomposition of H2O2 solution, water and oxygen form. If the oxygen gas is collected over water at 25.0 C and a total pressure of 92.1 kPa, what volume of gas , in liters, can be expected to form if 18.0 grams of H2O2 are decomposed?

7.38 L



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How many liters of ozone, O3 can be destroyed at 200. K and 7.00 kPa if 100. grams of chlorine gas reacts according to the following equation.

Cl2 + 2O3 2ClO + 2O2

670 L


http://www.nasa.gov/centers/goddard/images/content/160657main_OZONE_large.jpg


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When 2.50 L of C3H8 at STP burns, what total volume of gaseous products is formed? The volume of the products is measured at 175°C and 1.14 atm.

C3H8 (g) + 5O2 (g) → 3CO2 (g) + 4H2O (g)

answer

Gas Stoichiometry ProblemGas Stoichiometry Problemp.

899

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Ch 11 Sec 3 Homework

Combined and Ideal Gas Law ProblemsPage 897 # 268, 272, 273; Page 898 # 287, 292, 294; Page 899 #300


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Ch 11 Sec 3 Homework

Gas Stoichiometry Problems Page 899 #310a, 312, 314 a-c, 315

Gases Chapter 10/11 Modern Chemistry

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