Q: A weather balloon is filled with 2.0 mol of helium and has a volume of 44 L. If more helium is added so that the total amount is 5.0 mol, what will the new volume be, assuming constant temperature and pressure?

$$V_2 = 44$$\ \mathrm{L} \times \dfrac{5.0\ \mathrm{mol}}{2.0\ \mathrm{mol}} = 110\ \mathrm{L}$$

Q: A scuba diver releases a 25.0 mL bubble at a depth where the pressure is 4.00 atm and the temperature is 11 °C. What will be the volume of the bubble when it reaches the surface, where the pressure is 1.00 atm and the temperature is 18 °C?

$$V_2 = 25.0$$\ \mathrm{mL} \times \dfrac{4.00\ \mathrm{atm}}{1.00\ \mathrm{atm}} \times \dfrac{291\ \mathrm{K}}{284\ \mathrm{K}} = 102\ \mathrm{mL}$$

Q: A hospital oxygen tank contains O$$_2 at 120 $$atm and 25 °C. If the tank is heated to 402 °C, what will be the new pressure inside the tank (assume constant volume)?

$$P_2 = 120$$\ \mathrm{atm} \times \dfrac{675\ \mathrm{K}}{298\ \mathrm{K}} = 270\ \mathrm{atm}$$

Q: A sample of helium gas has a volume of 5.40 L at 15 °C. What will be its volume at 42 °C, assuming constant pressure?

$$V_2 = 5.40$$\ \mathrm{L} \times \dfrac{315\ \mathrm{K}}{288\ \mathrm{K}} = 5.91\ \mathrm{L}$$

Q: A gas has a pressure of 0.750 atm at 128 °C. What is the temperature in Celsius if the pressure increases to 1.50 atm (n and V remain constant)?

$$T_2$$ = \dfrac{1.50\ \mathrm{atm} \times 401\ \mathrm{K}}{0.750\ \mathrm{atm}} = 802\ \mathrm{K};\ 802 - 273 = 529\ ^\circ\mathrm{C}$$

Question 1

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

Accepted Answer

Gas particles are far apart, move rapidly in straight lines, and have negligible attractive forces between them.

Question 2

A weather balloon is filled with 2.0 mol of helium and has a volume of 44 L. If more helium is added so that the total amount is 5.0 mol, what will the new volume be, assuming constant temperature and pressure?

Accepted Answer

$$V_2 = 44$$\ \mathrm{L} 	imes \dfrac{5.0\ \mathrm{mol}}{2.0\ \mathrm{mol}} = 110\ \mathrm{L}$$

Question 3

A scuba diver releases a 25.0 mL bubble at a depth where the pressure is 4.00 atm and the temperature is 11 °C. What will be the volume of the bubble when it reaches the surface, where the pressure is 1.00 atm and the temperature is 18 °C?

Accepted Answer

$$V_2 = 25.0$$\ \mathrm{mL} 	imes \dfrac{4.00\ \mathrm{atm}}{1.00\ \mathrm{atm}} 	imes \dfrac{291\ \mathrm{K}}{284\ \mathrm{K}} = 102\ \mathrm{mL}$$

Question 4

Which of the following best explains why gases are easily compressed compared to solids and liquids?

Accepted Answer

Gas particles occupy a much smaller volume than the container, so most of the volume is empty space.

Question 5

A hospital oxygen tank contains O$$_2 at 120 $$atm and 25 °C. If the tank is heated to 402 °C, what will be the new pressure inside the tank (assume constant volume)?

Accepted Answer

$$P_2 = 120$$\ \mathrm{atm} 	imes \dfrac{675\ \mathrm{K}}{298\ \mathrm{K}} = 270\ \mathrm{atm}$$

Question 6

Which of the following is the correct expression for Boyle’s Law?

Accepted Answer

$$P_1$$ $$V_1$$ = $$P_2$$ $$V_2$$

Question 7

A sample of helium gas has a volume of 5.40 L at 15 °C. What will be its volume at 42 °C, assuming constant pressure?

Accepted Answer

$$V_2 = 5.40$$\ \mathrm{L} 	imes \dfrac{315\ \mathrm{K}}{288\ \mathrm{K}} = 5.91\ \mathrm{L}$$

Question 8

Which of the following is NOT a property used to describe the state of a gas?

Accepted Answer

Density (d)

Question 9

A sample of nitrogen gas occupies 215 mL at 0.813 atm and 30.0 °C. How many moles of N$$_2$$ are present? (Use $$R = 0.0821\ \mathrm{L \cdot atm \cdot $$mol^{-1}$$ \cdot K$$^{-1}$$})$$

Accepted Answer

$$n = \dfrac{(0.813\ \mathrm{atm})(0.215\ \mathrm{L})}{(0.0821\ \mathrm{L \cdot atm \cdot $$mol^{-1}$$ \cdot K$$^{-1}$$})(303\ \mathrm{K})} = 0.0070\ \mathrm{mol}$$

Question 10

Which of the following best describes what happens during inhalation in the human body?

Accepted Answer

The lungs expand, pressure decreases, and air flows in.

Question 11

A gas has a pressure of 0.750 atm at 128 °C. What is the temperature in Celsius if the pressure increases to 1.50 atm (n and V remain constant)?

Accepted Answer

$$T_2$$ = \dfrac{1.50\ \mathrm{atm} 	imes 401\ \mathrm{K}}{0.750\ \mathrm{atm}} = 802\ \mathrm{K};\ 802 - 273 = 529\ ^\circ\mathrm{C}$$

Question 12

Which of the following is the correct value for the gas constant $$R in $$the ideal gas law?

Accepted Answer

$$R = 0.0821\ \mathrm{L \cdot atm \cdot $$mol^{-1}$$ \cdot K$$^{-1}$$}$$

Question 13

A mixture of gases contains O$$_2$$ and He. If the total pressure is 7.00 atm and the partial pressure of O$$_2 is 1140 $$mmHg, what is the partial pressure of He in atm? (1 atm = 760 mmHg)

Accepted Answer

$$P_{\mathrm{He}} = 7.00\ \mathrm{atm} - \dfrac{1140\ \mathrm{mmHg}}{760\ \mathrm{mmHg/atm}} = 5.5\ \mathrm{atm}$$

Question 14

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 the individual gases.

Question 15

Which of the following is the correct combined gas law equation?

Accepted Answer

$$\dfrac{P_1$ V_1$}{T_1$} = \dfrac{P_2$ V_2$}{T_2$}$$

Question 16

A 5.00 L container holds 0.350 mol of N$$_2O at 22$$ °C. What is the pressure in the container? (Use $$R = 0.0821\ \mathrm{L \cdot atm \cdot $$mol^{-1}$$ \cdot K$$^{-1}$$})$$

Accepted Answer

$$P = \dfrac{(0.350\ \mathrm{mol})(0.0821\ \mathrm{L \cdot atm \cdot $$mol^{-1}$$ \cdot K$$^{-1}$$})(295\ \mathrm{K})}{5.00\ \mathrm{L}} = 1.69\ \mathrm{atm}$$

Question 17

Which of the following is a correct conversion for expressing 475 mmHg in atm?

Accepted Answer

$$475\ \mathrm{mmHg} 	imes \dfrac{1\ \mathrm{atm}}{760\ \mathrm{mmHg}} = 0.625\ \mathrm{atm}$$

Chapter 11: Gases – Properties, Laws, and Calculations

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