AP Chemistry Gases Review

A 0.5 mol sample of He gas and a 0.5 mol sample of Ne gas are placed seaprately in two 10.0 L rigid containers at 25 degrees C. Each container has a pinhole opening. Which of the gases, He or Ne, will escape through the pinhole faster and why?

• He will escape faster because the He atoms are moving at a higher average speed than the Ne atoms.

• Ne will escape faster because its initial pressure in the container is higher.

• Ne will escape faster because the Ne atoms have a higher average kinetic energy than the He atoms.

• Both gases will escape at the same rate because the atoms of both gases have the same kinetic energy.

A 2 L container will hold about 4 grams of which of the following gases at 0 degrees C and 1 atm?

• SO₂

• N₂

• CO₂

• NH₃

A 2 L sample of N₂ and a 1 L sample of Ar, each originally at 1 atm and 273 K, are combined in a 1 L tank. If the temperature is held constant, what is the total pressure of the gases in the tank?

• 1 atm

• 2 atm

• 3 atm

• 4 atm

A rigid metal tank contains oxygen gas. Which of the following applies to the gas in the tank when additional oxygen is added at constant temperature?

• The volume of the gas increases

• The pressure of the gas decreases

• The average speed of the gas molecules remains the same

• The average distance between the gas molecules increases.

A sample of an ideal gas is cooled from 50.0 degrees C to 25.0 degrees C in a sealed container of constant volume. Which of the following values for the gas will decrease?

I. The average molecular mass of the gas

II. The average distance between the molecules

III. The average speed of the molecules

• I only

• II only

• III only

• I and III

Which of the following gases deviates most from ideal behavior?

• SO₂

• Ne

• CH₄

• N₂

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?

• The density of the gas

• The pressure of the gas

• The average velocity of the gas molecules

• The potential energy of the molecules

When 6.0 L of Helium gas and 10. L of N₂ gas, both at 0 C and 1.0 atm, are pumped into an evacuated 4.0 L rigid container, the final pressure in the container at 0 C is

• 2.0 atm

• 4.0 atm

• 6.4 atm

• 8.8 atm

An equimolar mixture of N₂ and Ar gases is kept inside a rigid container at a constant temperature of 300 K. The initial pressure of Ar in the mixture is 0.75 atm. An additional amount of Ar was added to the container, enough to double the number of moles of Ar gas in the mixture. Assuming ideal behavior, what is the final pressure of the gas mixture after the addition of the Ar gas?

• 0.75 atm, because increasing the partial pressure of Ar decreases the partial pressure of nitrogen

• 1.13, because 33% of the moles of gas are Nitrogen

• 1.50, because the number of moles of Nitrogen did not change

• 2.25, because doubling the number of moles of Ar doubles its partial pressure.