Q: Which equation represents Boyle’s Law for a gas at constant temperature and number of particles?

$$P \times V = \text{constant}$$

Q: A sample of gas occupies 2.80 L at an unknown temperature. When cooled to 0 ºC, its volume decreases to 2.57 L. What was the initial temperature in kelvin?

$$T_1$$ = \frac{$$V_1$$}{$$V_2$$} \times $$T_2$$ = \frac{2.80}{2.57} \times 273 = 297 \text{ K}$$

Q: Convert a pressure of 0.311 atm to mm Hg. (1 atm = 760 mm Hg)

$$0.311 \times 760 = 236 \text{ mm Hg}$$

Q: A mixture of helium, neon, and argon has a total pressure of 558 mm Hg. If the partial pressure of helium is 341 mm Hg and neon is 112 mm Hg, what is the partial pressure of argon?

$$P_{\text{Ar}} = 558 - (341 + 112) = 105 \text{ mm Hg}$$

Q: A 4.8-L sample of helium contains 0.22 mol. How many additional moles are needed to reach 6.4 L at constant temperature and pressure?

$$n_2$$ = \frac{6.4}{4.8} \times 0.22 = 0.293 \text{ mol}$$; additional moles = 0.293 - 0.22 = 0.073$$ \text{ mol}$$

Question 1

According to the kinetic molecular theory, which statement best explains why gases are compressible?

Accepted Answer

Gas particles have negligible volume compared to the space between them.

Question 2

A scuba diver at a depth of 20 m breathes air at a pressure of 3 atm. If the diver ascends rapidly to the surface (1 atm) while holding their breath, what happens to the volume of air in their lungs according to Boyle’s Law?

Accepted Answer

The volume increases by a factor of 3.

Question 3

Which equation represents Boyle’s Law for a gas at constant temperature and number of particles?

Accepted Answer

$$P 	imes V = 	ext{constant}$$

Question 4

A sample of gas occupies 2.80 L at an unknown temperature. When cooled to 0 ºC, its volume decreases to 2.57 L. What was the initial temperature in kelvin?

Accepted Answer

$$T_1$$ = \frac{$$V_1$$}{$$V_2$$} 	imes $$T_2$$ = \frac{2.80}{2.57} 	imes 273 = 297 	ext{ K}$$

Question 5

Which of the following best describes why hot air balloons rise?

Accepted Answer

Heating the air decreases its density, causing it to float in cooler, denser air.

Question 6

Convert a pressure of 0.311 atm to mm Hg. (1 atm = 760 mm Hg)

Accepted Answer

$$0.311 	imes 760 = 236 	ext{ mm Hg}$$

Question 7

A mixture of helium, neon, and argon has a total pressure of 558 mm Hg. If the partial pressure of helium is 341 mm Hg and neon is 112 mm Hg, what is the partial pressure of argon?

Accepted Answer

$$P_{	ext{Ar}} = 558 - (341 + 112) = 105 	ext{ mm Hg}$$

Question 8

Which of the following is NOT a property predicted by the kinetic molecular theory for gases?

Accepted Answer

Gas particles attract each other strongly.

Question 9

A 4.8-L sample of helium contains 0.22 mol. How many additional moles are needed to reach 6.4 L at constant temperature and pressure?

Accepted Answer

$$n_2$$ = \frac{6.4}{4.8} 	imes 0.22 = 0.293 	ext{ mol}$$; additional moles = 0.293 - 0.22 = 0.073$$ 	ext{ mol}$$

Question 10

Which equation is the ideal gas law?

Accepted Answer

$$PV = nRT$$

Question 11

A sample of gas has a mass of 0.136 g, a volume of 0.112 L, a temperature of 298 K, and a pressure of 1.06 atm. What is the molar mass of the gas?

Accepted Answer

$$M = \frac{0.136}{n}$$, where $$n = \frac{PV}{RT} = \frac{1.06 	imes 0.112}{0.0821 	imes 298} = 0.0049 	ext{ mol}$$; $$M = \frac{0.136}{0.0049} = 27.8 	ext{ g/mol}$$

Question 12

Which of the following statements about partial pressures is correct?

Accepted Answer

The partial pressure of a gas in a mixture is equal to its fractional composition times the total pressure.

Question 13

A diver breathes a heliox mixture containing 2.0% oxygen at a depth of 90 m where the total pressure is 10.0 atm. What is the partial pressure of oxygen?

Accepted Answer

$$P_{	ext{O}_2$$} = 0.02 	imes 10.0 = 0.2 	ext{ atm}$$

Question 14

Which condition would cause a gas to behave most ideally?

Accepted Answer

High temperature and low pressure.

Question 15

Which of the following is a major gaseous air pollutant that is a lung and eye irritant and a precursor to acid rain?

Accepted Answer

Sulfur dioxide ($$	ext{SO}_2)$$

Question 16

At standard temperature and pressure (STP), what is the volume occupied by 1 mole of any ideal gas?

Accepted Answer

$$22.4 	ext{ L}$$

Question 17

A sample of gas has an initial volume of 158 mL at a pressure of 735 mm Hg and a temperature of 34 ºC. If the gas is compressed to 108 mL and heated to 85 ºC, what is its final pressure in mm Hg? (Use the combined gas law.)

Accepted Answer

$$P_2$$ = $$P_1$$ \frac{$$V_1$$}{$$V_2$$} \frac{$$T_2$$}{$$T_1$$} = 735 	imes \frac{158}{108} 	imes \frac{358}{307} = 1247 	ext{ mm Hg}$$

Question 18

Which law states that the volume of a gas is directly proportional to the number of moles at constant temperature and pressure?

Accepted Answer

Avogadro’s Law

Chapter 11: Gases – Properties, Laws, and Applications

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