Q: A sample of gas has a volume of 2.80 L at an unknown temperature. When cooled to 0.00 °C, its volume decreases to 2.57 L. What was its initial temperature in Kelvin?

$T_1 = \frac{2.80}{2.57} \times 273 = 297$ K

Q: If a tire is inflated to 132 psi, what is the pressure in mm Hg? (Given: $1 \text{ atm} = 14.7 \text{ psi} = 760 \text{ mm Hg}$)

$132 \text{ psi} \times \frac{760 \text{ mm Hg}}{14.7 \text{ psi}} = 6,822 \text{ mm Hg}$

Q: A 6.15 L lung contains 0.254 mol of air. After exhalation, the volume is 2.55 L. How many moles of air remain, assuming constant temperature and pressure?

$n_2 = \frac{2.55}{6.15} \times 0.254 = 0.105$ mol

Q: What is the density of nitrogen gas ($N_2$) at STP? ($M = 28.02 \text{ g/mol}$, $V_m = 22.4 \text{ L/mol}$)

$d = \frac{28.02}{22.4} = 1.25 \text{ g/L}$

Q: A 8.50 L tire contains 0.552 mol of an ideal gas at 305 K. What is the pressure in atm? ($R = 0.08206 \text{ L atm} / \text{mol K}$)

$P = \frac{nRT}{V} = \frac{0.552 \times 0.08206 \times 305}{8.50} = 1.62 \text{ atm}$

Question 1

Which of the following statements best describes the kinetic molecular theory of gases?

Accepted Answer

Gas particles are in constant random motion, with negligible attractions and volume compared to the container.

Question 2

A diver at a depth of 20 m experiences a pressure of approximately 3 atm. If the diver quickly ascends to the surface (1 atm) without exhaling, what happens to the volume of air in the diver's lungs?

Accepted Answer

The volume increases by a factor of 3.

Question 3

Which equation correctly relates pressure, force, and area for a gas?

Accepted Answer

$P = \frac{F}{A}$

Question 4

A sample of gas has a volume of 2.80 L at an unknown temperature. When cooled to 0.00 °C, its volume decreases to 2.57 L. What was its initial temperature in Kelvin?

Accepted Answer

$T_1 = \frac{2.80}{2.57} 	imes 273 = 297$ K

Question 5

Which of the following is NOT a standard condition for gases (STP)?

Accepted Answer

Temperature = 25 °C

Question 6

If a tire is inflated to 132 psi, what is the pressure in mm Hg? (Given: $1 	ext{ atm} = 14.7 	ext{ psi} = 760 	ext{ mm Hg}$)

Accepted Answer

$132 	ext{ psi} 	imes \frac{760 	ext{ mm Hg}}{14.7 	ext{ psi}} = 6,822 	ext{ mm Hg}$

Question 7

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

Accepted Answer

Charles's Law

Question 8

A 6.15 L lung contains 0.254 mol of air. After exhalation, the volume is 2.55 L. How many moles of air remain, assuming constant temperature and pressure?

Accepted Answer

$n_2 = \frac{2.55}{6.15} 	imes 0.254 = 0.105$ mol

Question 9

Which of the following best explains why atmospheric pressure decreases with increasing altitude?

Accepted Answer

The number of gas particles per unit volume decreases with altitude.

Question 10

What is the density of nitrogen gas ($N_2$) at STP? ($M = 28.02 	ext{ g/mol}$, $V_m = 22.4 	ext{ L/mol}$)

Accepted Answer

$d = \frac{28.02}{22.4} = 1.25 	ext{ g/L}$

Question 11

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

Accepted Answer

$PV = nRT$

Question 12

A 8.50 L tire contains 0.552 mol of an ideal gas at 305 K. What is the pressure in atm? ($R = 0.08206 	ext{ L atm} / 	ext{mol K}$)

Accepted Answer

$P = \frac{nRT}{V} = \frac{0.552 	imes 0.08206 	imes 305}{8.50} = 1.62 	ext{ atm}$

Question 13

Which property of gases is directly proportional to the number of moles at constant pressure and temperature?

Accepted Answer

Volume

Question 14

Which of the following is a correct statement of Boyle's Law?

Accepted Answer

$P_1 V_1 = P_2 V_2$

Question 15

Which of the following is true about the mean free path of a gas molecule?

Accepted Answer

It is the average distance a molecule travels before colliding with another molecule.

Question 16

Which modification to the ideal gas law accounts for the volume occupied by gas molecules?

Accepted Answer

Subtracting $nb$ from the volume: $V - nb$

Question 17

According to Graham's Law, how does the rate of effusion of a gas depend on its molar mass?

Accepted Answer

Rate is inversely proportional to the square root of molar mass: $	ext{rate} \propto \frac{1}{\sqrt{M}}$

Question 18

Which of the following is true about partial pressures in a mixture of gases?

Accepted Answer

The sum of the partial pressures equals the total pressure.

Chapter 10: Gases – Properties, Laws, and Applications

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