Question 1

A weather balloon is filled with helium gas to a pressure of 745 mm Hg at sea level. What is this pressure in atmospheres? (1 atm = 760 mm Hg)

Accepted Answer

$$0.980\ 	ext{atm}$$

Question 2

A sample of nitrogen gas occupies 2.50 L at 1.00 atm and 300 K. What volume will it occupy at 2.00 atm and 300 K, assuming ideal behavior?

Accepted Answer

$$1.25\ 	ext{L}$$

Question 3

Which of the following best explains why a gas exerts pressure on the walls of its container, according to the kinetic molecular theory?

Accepted Answer

Gas molecules collide with the walls, transferring momentum and creating pressure.

Question 4

A 5.00 g sample of oxygen gas ($$O_2) is $$collected in a 10.0 L container at 27°C. What is the pressure in the container? ($$R = 0.0821\ 	ext{L} \cdot 	ext{atm} / 	ext{mol} \cdot 	ext{K}$$, $$M_{O_2$} = 32.0\ 	ext{g/mol})$$

Accepted Answer

$$0.154\ 	ext{atm}$$

Question 5

A mixture contains 2.0 mol of $$N_2$$ and 3.0 mol of $$O_2 in a 10.0 L $$container at 300 K. What is the total pressure of the mixture? ($$R = 0.0821\ 	ext{L} \cdot 	ext{atm} / 	ext{mol} \cdot 	ext{K})$$

Accepted Answer

Question 6

Which of the following statements about the rates of effusion of gases is correct according to Graham's law?

Accepted Answer

Lighter gases effuse faster than heavier gases because their average speed is higher.

Question 7

A gas has a density of $$1.25\ 	ext{g/L} at $$STP ($$0^\circC$$, 1 atm). What is its molar mass?

Accepted Answer

$$28.0\ 	ext{g/mol}$$

Question 8

A reaction produces 2.00 L of $$CO_2$$ gas at 25°C and 1.00 atm. How many grams of $$CO_2$$ are produced? ($$R = 0.0821\ 	ext{L} \cdot 	ext{atm} / 	ext{mol} \cdot 	ext{K}$$, $$M_{CO_2$} = 44.0\ 	ext{g/mol})$$

Accepted Answer

$$3.57\ 	ext{g}$$

Question 9

A scuba tank contains a mixture of helium and oxygen at a total pressure of 8.00 atm. If the partial pressure of oxygen is 2.00 atm, what is the mole fraction of helium in the tank?

Accepted Answer

$$0.75$$

Question 10

Which of the following best describes the relationship between temperature and the average kinetic energy of a gas?

Accepted Answer

The average kinetic energy of a gas is directly proportional to its absolute temperature.

Question 11

A 10.0 L cylinder contains 0.500 mol of $$Ar$$ gas at 27°C. What is the pressure in the cylinder? ($$R = 0.0821\ 	ext{L} \cdot 	ext{atm} / 	ext{mol} \cdot 	ext{K})$$

Accepted Answer

$$1.22\ 	ext{atm}$$

Question 12

A gas sample is collected over water at 25°C. The total pressure is 755 mm Hg, and the vapor pressure of water at 25°C is 23.8 mm Hg. What is the partial pressure of the dry gas?

Accepted Answer

$$731.2\ 	ext{mm Hg}$$

Question 13

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

Accepted Answer

Gas molecules are attracted to each other by strong forces.

Question 14

A 2.00 L container holds 0.100 mol of $$SO_2$$ gas at 27°C. What is the density of the gas in g/L? ($$M_{SO_2$} = 64.1\ 	ext{g/mol})$$

Accepted Answer

$$3.21\ 	ext{g/L}$$

Question 15

A 1.00 L flask contains 0.0400 mol of $$H_2$$ and 0.0200 mol of $$N_2 at 300 K. $$What is the partial pressure of $$H_2$$? ($$R = 0.0821\ 	ext{L} \cdot 	ext{atm} / 	ext{mol} \cdot 	ext{K})$$

Accepted Answer

$$0.984\ 	ext{atm}$$

Question 16

A gas sample at 2.00 atm and 300 K is compressed to half its original volume and heated to 600 K. What is the new pressure?

Accepted Answer

$$8.00\ 	ext{atm}$$

Question 17

Which of the following real-world scenarios best illustrates the concept of diffusion of gases?

Accepted Answer

The smell of perfume spreading across a room.

Question 18

A reaction requires 5.00 L of $$O_2 at 1.00 $$atm and 273 K. How many grams of $$O_2$$ are needed? ($$R = 0.0821\ 	ext{L} \cdot 	ext{atm} / 	ext{mol} \cdot 	ext{K}$$, $$M_{O_2$} = 32.0\ 	ext{g/mol})$$

Accepted Answer

$$7.14\ 	ext{g}$$

Question 19

If the molar mass of gas A is four times that of gas B, what is the ratio of the rate of effusion of gas B to gas A?

Accepted Answer

$$2:1$$

Question 20

A gas cylinder contains a mixture of 1.0 mol $$He$$, 2.0 mol $$Ne$$, and 3.0 mol $$Ar. If $$the total pressure is 6.0 atm, what is the partial pressure of $$Ne$$?

Accepted Answer

$$2.0\ 	ext{atm}$$

Gases: Pressure, Laws, and Kinetic Molecular Theory

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