Chapter 13: GasesPractice Problems
I. Conversions
a. 795 mm Hg to atmanswer: 1.05 atm
b. 0.981 atm to torr746 torr
c. 732 mm Hg to Pa9.76 x 104Pa
d. 83.0 atm to psi1220 psi
e. 570. torr to atm0.750 atm
f. 35 psi to mm Hg1800 mm Hg
II. Gas Laws
1. A balloon occupies 40. L at 760. mm Hg. How much volume will it have at 900. mm Hg?
(assume T = constant)ans: 34 L
2. A diver’s scuba tank holds 20. L of compressed air at 9.0 atm. What size tank would be needed at 1.2 atm? (T = constant) ans: 150 L
3. A thermos bottle was sealed at 760 mm Hg at 25ºC. In the back of the car4 it heats to 45°C and “blows up.” Assuming the volume remains the same, at what pressure did the glass break? Answer in atm.
ans: 1.1 atm
4.. If a gas has a volume of 10. L at 145 atm, what will be its volume at 75 atm? (T=constant)
ans: 19 L
5. A balloon has a volume of 41.1 L at 75ºC. What will its temperature be if it shrinks to 35.2 L with no change in pressure? ans: 25°C
6. A gas that initially had a volume of 175 L at 15 atm and 298 K was compressed to 75 L at 5.0 atm. What is the new temperature of the gas? ans: 43K
7. What will be the volume at STP of a sample of gas that occupies 35.2 ml at 270.°C and .976 atm?
ans: 17.3 ml
8. What will be the temperature of a gas that was originally at 20. L and 4.0 atm and 25°C but is compressed to 10 L and 40 atm? ans: 1200°C
9. A small ball has a pressure of 3.0 atm, a volume of 2.0 L and a temperature of 15ºC. It is placed in an airplane which travels to 20,000 ft. where the pressure in the ball changes to 1.2 atm, and its temperature becomes 0ºC. What is its new volume? ans: 4.7 L
10. The safety limit for a certain can of aerosol spray is 95°C. If the pressure of the gas in the can is 2.96 atm when it is at 17ºC, what will the pressure be at the safety limit? ans: 3.76 atm
11. A sample of nitrogen collected in the laboratory occupies a volume of 725 ml at a pressure of 0.971 atm. What volume will the gas occupy at a pressure of 1.40 atm, assuming the temperature remains constant?
ans: 503 ml
12. A chemist collects 59.0 ml of sulfur dioxide gas on a day when the atmospheric pressure is 0.989 atm. On the next day, the pressure has changed to 0.967 atm. What will the volume of the SO2 gas be on the second day? ans: 60.3 ml
13. A cylinder of compressed gas has a pressure of 4.882 atm on one day. The next day, the same cylinder of gas has a pressure of 4.690 atm, and its temperature is 8ºC. What was the temperature on the previous day?
ans: 20.ºC
14. A balloon full of air has a volume of 2.75 L at a temperature of 18ºC. What is the balloon’s volume at 45°C? ans: 3.01 L
III Ideal Gas Law
15. If 1.30 moles of a gas occupy 74.0 L at 4.0 atm, what is the temperature of this gas?ans: 2500 K
16. How many moles of a gas are in 529 L container at -12ºC and 0.255 atm?ans: 6.3 moles
17. What is the volume occupied by 1.00 moles of a gas at -75ºC and 12.49 atm?ans: 1.3 L
18. Calculate the pressure (in atm) needed to contain 10.58 grams of H2 gas at 45°C in a 3.45 L container?
ans: 40. atm
19. A sample of neon gas has a volume of 3.45 L at 25ºC and a pressure of 565 torr. Calculate the number of moles of neon present in this gas sample. ans: 0.105 mole
20. A 0.500 g sample of gas occupies a volume of 65 ml at 80.°C and 750 mm Hg. Determine how many moles are in the sample and the molar mass of the unknown gas. ans: .0022 moles
230 g/mol
IV. Partial Pressure
21. A 5.00 g sample of helium gas is added to a 5.00 g sample of neon in a 2.50 L container at 27°C. Calculate the partial pressure of each gas and the total pressure. ans: 12.3 atm He
2.44 atm Ne
14.7 atm total
22. A sample of oxygen gas is saturated with water vapor at 30.0ºC. The total pressure is 753 torr and the vapor pressure of water at 30.0°C is 31.824 torr. What is the partial pressure of the oxygen gas in atm? ans: 0.949 atm