AP CHEM Unit 11 Exam Review

The graph above shows the speed distribution of molecules in a sample of a gas at a certain temperature. Which of the following graphs shows the speed distribution of the same molecules at a lower temperature (as a dashed curve) ?

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Tags

NGSS.HS-PS1-5

The Maxwell-Boltzmann distributions of molecular speeds in samples of two different gases at the same temperature are shown above. Which gas has the greater molar mass?

• Gas A

• Gas B

• Both gases have the same molar mass.

• It cannot be determined unless the pressure of each sample is known.

Tags

NGSS.HS-PS3-2

At standard temperature and pressure, a 0.50 mol sample of H₂ gas and a separate 1.0 mol sample of O₂ gas are placed in identical rigid containers. The two samples have the same

• average molecular kinetic energy

• average molecular speed

• effusion rate

• density

Under which of the following conditions of temperature and pressure would 1.0 mol of the real gas CO₂(g) behave most like an ideal gas?

• 100 K and 0.10 atm

• 100 K and 100 atm

• 800 K and 0.10 atm

• 800 K and 10 atm

A 4 L container will hold about 18.7 g of which of the following gases at 20°C and 2 atm?

• SO₂

• N₂

• CO₂

• C₄H₈

A gas mixture at 0°C and 4.2atm contains 0.050mol of CO₂, 0.025mol of N₂, and 0.050mol of H₂O. Assuming ideal behavior, what is the partial pressure of water vapor (H₂O) in the mixture?

• About 0.4atm

• About 0.050atm

• About 1.7atm

• About 0.125atm

The temperature, in K, of 2.20mol of an ideal gas placed in a 6.0L container with a pressure of 722mmHg is given by which of the following expressions?

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Each sealed syringe contains 10mL of a different noble gas at standard temperature. The gases are then injected into a previously evacuated 50mL Erlenmeyer flask. What is the total pressure of the gases in the Erlenmeyer flask at standard temperature?

• 1.2atm

• 2.4atm

• 12atm

• 60atm

An empty aerosol-spray can at room temperature (20 ◦C) is thrown into an incinerator where the temperature reaches 463◦C. If the gas inside the empty container was initially at a pressure of 1 atm, what pressure did it reach inside the incinerator? Assume the gas was at constant volume and the can did not explode.

• 1.25atm

• 2.5atm

• 5.0atm

• 0.40atm

A mixture of two gases, 0.01mol of C₄H₁₀(g) and 0.065mol of O₂(g), is pumped into a cylinder with a movable piston, as shown above. The mixture, originally at 200°C and 1.0atm, is sparked and the reaction represented below occurs.

2C₄H₁₀(g)+13O₂(g)→8CO₂(g)+10H₂O(g)

Which of the following is true after the product gases return to the original temperature and pressure, and why will the change occur? (Assume all gases behave ideally.)

• The piston will be higher than its original position, because the cylinder will contain a greater number of gas molecules.

• The position of the piston will be unchanged, because the total mass of the gases in the cylinder does not change.

• The position of the piston will be unchanged, because the temperature and pressure of the contents of the cylinder remain the same.

• The piston will be lower than its original position, because the product molecules are smaller than the reactant molecules.

Tags

NGSS.HS-PS3-4