Q: A sample of gas has a volume of 6.20 L at 1.10 atm. What will its volume be at 0.925 atm, assuming constant temperature?

$$V_2$$ = \frac{P_1V_1}{$$P_2$$} = \frac{1.10 \times 6.20}{0.925} = 7.38$$ L

Q: A 23.0 L sample of NH$$_3$$ gas at 10.0°C is heated at constant pressure until it fills a volume of 50.0 L. What is the new temperature in °C?

$$T_2$$ = \frac{V_2T_1}{$$V_1$$} = \frac{50.0 \times 283}{23.0} = 615$$ K; 615 - 273 = 342°C

Q: At STP, what is the volume occupied by 0.946 mol of krypton gas?

$$V = 0.946 \times 22.4 = 21.2 L$$

Question 1

Which of the following best explains why a gas can be compressed much more easily than a liquid or a solid?

Accepted Answer

Gas molecules are far apart and have negligible interactions between them.

Question 2

A hospital oxygen tank reads 4840 mm Hg. What is the pressure in atmospheres? (1 atm = 760 mm Hg)

Accepted Answer

$$\frac{4840}{760} = 6.37$$ atm

Question 3

Which law describes the relationship between the pressure and volume of a gas at constant temperature?

Accepted Answer

Boyle's Law: $$P_1V_1 = P_2V_2$$

Question 4

A sample of gas has a volume of 6.20 L at 1.10 atm. What will its volume be at 0.925 atm, assuming constant temperature?

Accepted Answer

$$V_2$$ = \frac{P_1V_1}{$$P_2$$} = \frac{1.10 	imes 6.20}{0.925} = 7.38$$ L

Question 5

Which real-life scenario is an application of Boyle’s Law?

Accepted Answer

Breathing: As the diaphragm contracts, lung volume increases and pressure decreases, drawing air in.

Question 6

A 23.0 L sample of NH$$_3$$ gas at 10.0°C is heated at constant pressure until it fills a volume of 50.0 L. What is the new temperature in °C?

Accepted Answer

$$T_2$$ = \frac{V_2T_1}{$$V_1$$} = \frac{50.0 	imes 283}{23.0} = 615$$ K; 615 - 273 = 342°C

Question 7

Which of the following statements about Avogadro’s Law is correct?

Accepted Answer

Equal volumes of gases at the same temperature and pressure contain the same number of molecules.

Question 8

At STP, what is the volume occupied by 0.946 mol of krypton gas?

Accepted Answer

$$V = 0.946 	imes 22.4 = 21.2 L$$

Question 9

Which of the following is the correct form of the ideal gas law?

Accepted Answer

$$PV = nRT$$

Question 10

A 5.0 g sample of CO$$_2$$ gas is placed in a 10.0 L cylinder at 25°C. What is the pressure inside the cylinder? (R = 0.0821 L·atm/mol·K, molar mass CO$$_2 = 44.0 g/$$mol)

Accepted Answer

$$n = \frac{5.0}{44.0} = 0.114$$ mol; $$P = \frac{nRT}{V} = \frac{0.114 	imes 0.0821 	imes 298}{10.0} = 0.28$$ atm

Question 11

Which of the following best describes Dalton’s Law of Partial Pressures?

Accepted Answer

The total pressure of a mixture of gases is the sum of the partial pressures of each individual gas: $$P_T = P_1$ + P_2$ + P_3$ + \ldots$$

Question 12

A vessel contains nitrogen at 1.908 atm and water vapor. The total pressure is 2.015 atm. What is the partial pressure of the water vapor?

Accepted Answer

$$2.015 - 1.908 = 0.107$$ atm

Question 13

According to the kinetic molecular theory, which of the following statements is NOT an assumption for an ideal gas?

Accepted Answer

Gas particles have significant attractive forces between them.

Question 14

Which of the following intermolecular forces is the strongest?

Accepted Answer

Hydrogen bonding

Question 15

Which of the following molecules can form hydrogen bonds with itself?

Accepted Answer

Methanol ($$CH_3OH)$$

Question 16

Why does water have a much higher boiling point than methane, even though their molar masses are similar?

Accepted Answer

Water molecules form strong hydrogen bonds, while methane molecules only experience weak London dispersion forces.

Question 17

Which of the following best explains why a steel needle can float on the surface of water?

Accepted Answer

Water has a high surface tension due to strong hydrogen bonding among its molecules.

Question 18

Which phase change is described as a solid turning directly into a gas?

Accepted Answer

Sublimation

Question 19

Which of the following statements about the boiling point of a liquid is correct?

Accepted Answer

The boiling point is the temperature at which the vapor pressure of the liquid equals the atmospheric pressure.

Gases, Liquids, and Solids: States of Matter and Their Properties

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