Behavior of Gases
Chapter 12 Assignment & Problem Set
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Behavior of Gases
Chapter 12 Assignment & Problem Set
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Study Guide: Things You Must Know
Vocabulary (know the definition and what it means):
 state of matter
 Kinetic Molecular Theory (KMT)
 elastic collision
 molecular attractions (intermolecular forces)
 pressure
 atmospheric pressure
 Boyle’s Law
 Charles’ Law
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Avogardo’s Law
Ideal Gas Law (“pivnert”)
Combined Gas Law
ideal gas vs. real gas
Dalton’s Law of Partial Pressure
Diffusion vs. effusion
Honors: Graham’s Law of Diffusion
Learning Objectives:
 the statements (or assumptions) that make up Kinetic Molecular Theory.
 how to explain the Gas Laws using Kinetic Molecular Theory.
 what pressure is at the molecular level.
 how to interconvert units of pressure (atmospheres, mm Hg, pascals).
 Kelvin temperature is a measure of average kinetic energy.
 Kelvin temperature must be used in all Gas Law problems.
 when to use the Ideal Gas Law and when to use the Combined Gas Law.
 how to solve problems using the Ideal Gas Law and the Combined Gas Law.
 what distinguishes an “ideal gas” from a “real gas.”
 under what conditions of temperature and pressure a real gas is most like an ideal gas.
 How to solve problems with mixtures of gases using Dalton’s Law of partial pressures.
 Honors: how to calculate relative rates of diffusion and effusion using Graham’s Law.
Key Reference Tables
 Table A: Standard Temperature and Pressure
 Table T: Important Formulas and Equations
Behavior of Gases
Chapter 12 Assignment & Problem Set
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•Read Chapter 12. Regents students can skip the section on Graham’s Law, pp 352-353.
•Lab 11: Boyle’s Law
•Lab 11b: Charles’ Law
•Regents Tables:
Table A: Standard Temperature and Pressure
Table T: Important Formulas and Equations
•Warm-ups and problems will be collected before you take the test. Answer all problems in the space provided.
For problems involving an equation, carry out the following steps: 1. Write the equation.
2. Substitute numbers and units. 3. Show the final answer with units. There is no credit without showing work.
Kinetic Molecular Theory (KMT)
1. State the main assumptions of KMT.
2. What is the effect of adding gas to a container on the pressure in the container. Explain at the molecular level.
3. What is the effect of increasing the volume of a container on the pressure in the container. Explain at the
molecular level.
4. What is “STP”?
5. Why is Kelvin temperature used in all gas law calculations?
Two Variable Gas Laws
6. The pressure on 2.50 L of anesthetic gas changes from 105 kPa to 40.5 kPa. What will be the new volume if the
temperature remains constant?
7. Exactly 5.00 L of air at –50oC is warmed to 100oC. What is the new volume if the pressure remains constant?
Behavior of Gases
Chapter 12 Assignment & Problem Set
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8. The pressure in an automobile tire is 198 kPa at 27oC. At the end of a road trip on a hot day, the pressure in the
tire has risen to 225 kPa. What is the temperature of the air in the tire?
Ideal Gas Law
9. What is the value of the ideal gas constant?
10. When the temperature of a rigid 685 L container of helium gas is held at 621 K, the pressure in the container is
1.89 x 103 kPa. How many moles of helium is in the container? If the gas were CO2 instead of helium, how
many moles would there be in the container?
11. What volume will 12.0 g of oxygen gas occupy at 25oC and a pressure of 52.7 kPa?
12. A container holds 6.92 g of helium gas at STP. What is the volume of the container?
13. If the human lung has a volume of 3.1 L, how many grams of air at 102 kPa and at normal body temperature of
37oC will it hold. (Assume the average molar mass of air is 28 g/mol.)
Combined Gas Law
14. A gas at 155 kPa and 25oC occupies a volume of 1.0 L. By changing the volume, the pressure of the gas
increases to 605 kPa and the temperature increases to 125oC. What is the new volume?
15. A 5.00 L air sample at –50oC has a pressure of 0.78 atm. What will be the new pressure if the temperature is
raised to 102oC and the volume expands to 7.00 L?
Behavior of Gases
Chapter 12 Assignment & Problem Set
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Mixed-up Combined and Ideal Gas Law Problems!
Note: There are two main equations in this unit, the ideal gas law and the combined gas law. If conditions of P,
V, or T do not change, use the Ideal Gas Law. If conditions do change, use the Combined Gas Law.
1. Ideal Gas Law (alias “pivnert”): PV = nRT. The most error-free way to use this equation is to convert units:
 pressure (P) to atmospheres
 volume (V) to liters
 number of moles (n) to moles
 temperature (T) to Kelvin
 and use the gas constant R = 0.0821 L atm/mol K
2. Combined Gas Law: P1V1 = P2V2
T1
T2
This equation can be used with any units of P and V as long as they are the same on both sides. T must be in
Kelvin.
16. 11 g of methane (CH4) is placed in a rigid 820 mL container at 120oC. What is the pressure in the container?
17. Neon gas is placed in a 31 L tank at 35oC and a pressure of 750 kPa. What is the new pressure if the
temperature is changed to 120oC?
18. How many moles of propane (C3H8) are in a tank if the temperature is 27oC, the pressure is 450 kPa, and the
volume of the tank is 930 L?
19. Honors If the volume of a gas doubles and the Kelvin temperature triples, what happens to the pressure?
Dalton Law of Partial Pressures
20. Determine the total pressure of a gas mixture that contains the following partial pressures: P(O2) = 20.0 kPa,
P(N2) = 46.7 kPa, and P(He) = 26.7 kPa.
21. A gas mixture containing oxygen, nitrogen, and carbon dioxide has a total pressure of 32.9 kPa. What is P(CO2)
if P(O2) = 6.6 kPa and P(N2) = 23.0 kPa?
Behavior of Gases
Chapter 12 Assignment & Problem Set
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Graham’s Law of Diffusion
22. Honors At the same temperature, the rates of diffusion of carbon monoxide and nitrogen at virtually the same.
Explain.
23. Honors Which gas diffuses faster, hydrogen or chlorine. How much faster?
24. Honors A certain gas diffuses four time faster than oxygen (O2). What is the molar mass of the gas?
Real vs. Ideal Gases
25. Define “ideal gas.”
26. Explain, on the molecular scale, why real gases deviate from ideal behavior.
27. Under what conditions of temperature and pressure do real gases behave most like ideal gases. Explain.
Review
28. Calculate the molar mass of calcium acetate.
29. How many kilojoules of heat are requires to warm 500 g of water from 22oC to 72oC?
30. Write an equation for the reaction of aluminum metal with a solution of copper (II) sulfate. What class of
reaction is this?
31. Calculate the molecular formula of a compound with an empirical formula of C2H4O and a molar mass of 88
g/mol.