Question 1

A 2.00 L sample of oxygen gas is collected at 25°C and 1.00 atm. What is the mass of oxygen in the sample? (Molar mass of O$$_2 = 32.00 g/$$mol)

Accepted Answer

$$2.62\ \mathrm{g}$$

Question 2

Which of the following statements is consistent with Boyle's Law concerning an ideal gas?

Accepted Answer

At constant temperature and moles, a plot of pressure versus volume is a hyperbola.

Question 3

A chemist vaporizes a liquid compound and determines its density. If the density of the vapor at 90°C and 753 mmHg is 1.585 g/L, what is the molar mass of the compound?

Accepted Answer

$$49.6\ \mathrm{g/mol}$$

Question 4

A scuba diver uses a tank containing 25.4 L of oxygen gas at a pressure of 13.8 atm and a temperature of 298 K. How many moles of gas are in the cylinder?

Accepted Answer

$$14.5\ \mathrm{mol}$$

Question 5

Which statement best describes the kinetic molecular theory as it applies to gases?

Accepted Answer

The average kinetic energy of molecules from samples of different 'ideal' gases is the same at the same temperature.

Question 6

A 5.00 L sample of oxygen is collected over water at a total pressure of 699.7 mmHg and 19°C. The vapor pressure of water at 19°C is 16.5 mmHg. What is the partial pressure of oxygen?

Accepted Answer

$$683.2\ \mathrm{mmHg}$$

Question 7

A sample of gas is compressed to a volume of 15.8 L and warmed to a temperature of 395 K. What is the final pressure of the gas if the initial conditions were 21.7 L at 288 K and 0.46 atm?

Accepted Answer

$$0.85\ \mathrm{atm}$$

Question 8

Calculate the grams of SO$$_2$$ gas present at STP in a 5.9 L container. (Molar mass SO$$_2 = 64.07 g/$$mol)

Accepted Answer

$$16.9\ \mathrm{g}$$

Question 9

What is the density of oxygen gas at STP? Be careful with significant figures. STP is 1 atm and 0°C.

Accepted Answer

$$1.43\ \mathrm{g/L}$$

Question 10

A mixture of gases contains 0.25 mol CO$$_2$$, 0.50 mol Cl$$_2$$, and 0.10 mol O$$_2. $$What is the mole fraction of Cl$$_2 in $$the mixture?

Accepted Answer

$$0.56$$

Question 11

A chemist generates 724 mL of nitrogen gas and collects it over water at a temperature of 17°C and a pressure of 755 mmHg. The vapor pressure of water at 17°C is 14.5 mmHg. What is the mass of this nitrogen? (Molar mass N$$_2 = 28.0134 g/$$mol)

Accepted Answer

$$0.84\ \mathrm{g}$$

Question 12

What is the root mean square (rms) speed of N$$_2 at $$STP? (Molar mass N$$_2 = 28.0134 g/$$mol)

Accepted Answer

$$517\ \mathrm{m/s}$$

Question 13

Which of the following best explains why deviations from the ideal gas law are greater at high pressures?

Accepted Answer

Gas molecules are closer together and intermolecular forces become significant.

Question 14

A 0.213 mol sample of helium gas is at a pressure of 1.05 atm and a temperature of 315 K. What is the volume occupied by the gas?

Accepted Answer

$$5.24\ \mathrm{L}$$

Question 15

A sample of gas at 1.00 atm and 25°C is cooled to 0°C at constant pressure. What happens to the volume?

Accepted Answer

The volume decreases.

Question 16

Which of the following is the correct formula for calculating the density of a gas using the ideal gas law?

Accepted Answer

$$d = \frac{P M}{R T}$$

Question 17

A mixture of gases is collected over water at 25°C and a total pressure of 760 mmHg. The vapor pressure of water at 25°C is 23.8 mmHg. What is the partial pressure of the dry gas?

Accepted Answer

$$736.2\ \mathrm{mmHg}$$

Question 18

A 0.320 mol sample of hydrogen gas has a volume of 2.00 L at a certain temperature and pressure. What is the volume of 0.125 mol of this gas at the same temperature and pressure?

Accepted Answer

$$0.80\ \mathrm{L}$$

Question 19

At what temperature will a sample of oxygen gas with a volume of 0.110 L at 12°C and 822 mg/g occupy a volume of 345 mL at a pressure of 578 mm Hg? Assume the amount of oxygen does not change.

Accepted Answer

$$87\ ^\circ\mathrm{C}$$

General Chemistry Study Notes: Gases, Gas Laws, and Stoichiometry

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