Q: A sample of methane gas occupies 5.00 L at 1.00 atm and 300 K. What will be its volume if the pressure is increased to 2.00 atm at constant temperature?

$$V_2$$ = \frac{$$P_1$$ $$V_1$$}{$$P_2$$} = \frac{1.00 \times 5.00}{2.00} = 2.50\ \mathrm{L}$$

Q: At STP, what is the volume occupied by 2 moles of an ideal gas?

$$V = 2 \times 22.4\ \mathrm{L} = 44.8\ \mathrm{L}$$

Q: A gas sample has a mass of 4.00 g, occupies 2.00 L at 1.00 atm and 273 K. What is its molar mass?

$$M = \frac{mRT}{PV} = \frac{4.00 \times 0.0821 \times 273}{1.00 \times 2.00} = 44.9\ \mathrm{g/mol}$$

Q: A mixture contains 2.0 mol of O$$_2$$ and 3.0 mol of N$$_2 in a 10.0 L $$container at 300 K. What is the total pressure in the container?

$$P = \frac{nRT}{V} = \frac{(2.0 + 3.0) \times 0.0821 \times 300}{10.0} = 12.3\ \mathrm{atm}$$

Q: A 10.0 L container holds a mixture of 1.0 mol $$CO_2$$ and 2.0 mol $$O_2 at 300 K. $$What is the partial pressure of $$O_2$$?

$$P_{O_2$} = \frac{n$$_{O_2}$$RT}{V} = \frac{2.0 \times 0.0821 \times 300}{10.0} = 4.93\ \mathrm{atm}$$

Question 1

Which of the following statements best explains why gases are highly compressible compared to liquids and solids?

Accepted Answer

Gases consist of molecules with negligible volume relative to the container.

Question 2

A sample of methane gas occupies 5.00 L at 1.00 atm and 300 K. What will be its volume if the pressure is increased to 2.00 atm at constant temperature?

Accepted Answer

$$V_2$$ = \frac{$$P_1$$ $$V_1$$}{$$P_2$$} = \frac{1.00 	imes 5.00}{2.00} = 2.50\ \mathrm{L}$$

Question 3

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

Accepted Answer

$$V \propto T$$

Question 4

At STP, what is the volume occupied by 2 moles of an ideal gas?

Accepted Answer

$$V = 2 	imes 22.4\ \mathrm{L} = 44.8\ \mathrm{L}$$

Question 5

A gas sample has a mass of 4.00 g, occupies 2.00 L at 1.00 atm and 273 K. What is its molar mass?

Accepted Answer

$$M = \frac{mRT}{PV} = \frac{4.00 	imes 0.0821 	imes 273}{1.00 	imes 2.00} = 44.9\ \mathrm{g/mol}$$

Question 6

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 pressures each gas would exert if it were present alone.

Question 7

A mixture contains 2.0 mol of O$$_2$$ and 3.0 mol of N$$_2 in a 10.0 L $$container at 300 K. What is the total pressure in the container?

Accepted Answer

$$P = \frac{nRT}{V} = \frac{(2.0 + 3.0) 	imes 0.0821 	imes 300}{10.0} = 12.3\ \mathrm{atm}$$

Question 8

Which of the following is NOT an assumption of the kinetic-molecular theory of gases?

Accepted Answer

Gas molecules exert significant attractive and repulsive forces on each other.

Question 9

If the temperature of a gas is doubled at constant volume, what happens to the pressure?

Accepted Answer

The pressure doubles.

Question 10

Which equation correctly relates the density of a gas to its molar mass, pressure, and temperature?

Accepted Answer

$$d = \frac{MP}{RT}$$

Question 11

A gas effuses through a tiny hole at a rate that is twice as fast as another gas. What is the ratio of their molar masses ($$M_1$$ for the faster gas, $$M_2$$ for the slower gas)?

Accepted Answer

$$\frac{M_2$}{M_1$} = 4$$

Question 12

Which of the following gases would have the highest root-mean-square speed ($$u_{rms}) at $$the same temperature?

Accepted Answer

Hydrogen ($$H_2)$$

Question 13

A manometer is used to measure the pressure of a gas in a vessel. If the mercury column is 50 mm higher on the open end than the vessel end and atmospheric pressure is 760 mm Hg, what is the pressure of the gas?

Accepted Answer

$$P_{gas} = P_{atm} + h = 760\ \mathrm{mm\ Hg} + 50\ \mathrm{mm\ Hg} = 810\ \mathrm{mm\ Hg}$$

Question 14

Which of the following best explains why real gases deviate from ideal behavior at low temperatures and high pressures?

Accepted Answer

Intermolecular forces and the finite volume of molecules become significant.

Question 15

Which equation is used to correct for nonideal behavior in real gases?

Accepted Answer

The van der Waals equation

Question 16

A 10.0 L container holds a mixture of 1.0 mol $$CO_2$$ and 2.0 mol $$O_2 at 300 K. $$What is the partial pressure of $$O_2$$?

Accepted Answer

$$P_{O_2$} = \frac{n$$_{O_2}$$RT}{V} = \frac{2.0 	imes 0.0821 	imes 300}{10.0} = 4.93\ \mathrm{atm}$$

Question 17

Which of the following is the correct value for the ideal gas constant $$R in $$units of $$\mathrm{L\ atm\ $$mol^{-1}$$\ K$$^{-1}$$}$$?

Accepted Answer

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

Question 18

Which of the following gases is most likely to behave ideally under standard conditions?

Accepted Answer

Helium ($$He)$$

Chapter 10: Gases – Properties, Laws, and Applications

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