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Ch 11 Gases – AP Practice Questions
AP Chem 2011-12
1984
1. When a sample of oxygen gas in a closed container of constant volume is heated until its absolute
temperature is doubled, which of the following is also doubled?
a. The density of the gas
b. The pressure of the gas
c. The average velocity of the gas molecules
d. The number of molecules per cm3
e. The potential energy of the molecules
2. The density of an unknown gas is 4.20 grams per liter at 3.00 atmospheres pressure and 127°C. What is the
molecular weight of this gas? (R = 0.0821liter-atm / mole-K)
a. 14.6 b. 46.0 c. 88.0 d. 94.1 e. 138
3. Equal masses of three different ideal gases, X, Y, and Z, are mixed in a sealed rigid container. If the
temperature of the system remains constant, which of the following statements about the partial pressure of
gas X is correct?
a. It is equal to 1/3 the total pressure.
b. It depends on the intermolecular forces of attraction between molecules of X, Y, and Z.
c. It depends on the relative molecular masses of X, Y, and Z.
d. It depends on the average distance traveled between molecular collisions.
e. It can be calculated with knowledge only of the volume of the container.
4. Two flexible containers for gases are at the same temperature and pressure. One holds 0.50 gram of
hydrogen and the other holds 8.0 grams of oxygen. Which of the following statements regarding these gas
samples is FALSE?
a. The volume of the hydrogen container is the same as the volume of the oxygen container.
b. The number of molecules in the hydrogen container is the same as the number of molecules in the
oxygen container.
c. The density of the hydrogen sample is less than that of the oxygen sample.
d. The average kinetic energy of the hydrogen molecules is the same as the average kinetic energy of the
oxygen molecules.
e. The average speed of the hydrogen molecules is the same as the average speed of the oxygen molecules.
5. A compound is heated to produce a gas whose molecular weight is to be determined. The gas is collected by
displacing water in a water-filled flask inverted in a trough of water. Which of the following is necessary to
calculate the molecular weight of the gas, but does NOT need to be measured during the experiment?
a. Mass of the compound used in the experiment
b. Temperature of the water in the trough
c. Vapor pressure of the water
d. Barometric pressure
e. Volume of water displaced from the flask
6. When the actual gas volume is greater then the volume predicted by the ideal gas law, the explanation lies
in the fact that the ideal gas law does NOT include a factor for molecular
a. volume
b. mass
c. velocity
d. attractions
e. shape
7. A sample of 9.00 grams of aluminum metal is added to an excess of hydrochloric acid. The volume of
hydrogen gas produced at standard temperature and pressure is
a. 22.4 L b. 11.2 L c. 7.46 L d. 5.60 L e. 3.74 L
