Q: A scuba diver holds their breath at sea level (1 atm) with a lung volume of 6.00 L. If the diver descends to a depth where the pressure is 2.5 atm, what will be the new volume of the diver's lungs, assuming temperature remains constant?

$$V_2$$ = \frac{$$P_1$$ $$V_1$$}{$$P_2$$} = \frac{1.0 \times 6.00}{2.5} = 2.4\ \text{L}$$

Q: A sample of gas occupies 1.25 L at $$91.3^\circC. $$What will its volume be if it is cooled to $$0.0^\circC at $$constant pressure?

$$V_2$$ = $$V_1$$ \frac{$$T_2$$}{$$T_1$$} = 1.25 \times \frac{273.15}{364.45} = 0.94\ \text{L}$$

Q: Which of the following is the correct value for the universal gas constant $$R$$ when using pressure in atm and volume in liters?

$$R = 0.08206\ \text{L} \cdot \text{atm} / \text{mol} \cdot \text{K}$$

Q: A 0.448 mole sample of $$N_2$$ gas is placed in a 15.0 L container at 325 K. What is the pressure of the gas?

$$P = \frac{nRT}{V} = \frac{0.448 \times 0.08206 \times 325}{15.0} = 0.797\ \text{atm}$$

Q: A mixture of gases contains 1.25 g of $$O_2$$ and 0.85 g of $$N_2 in a 1.55 L $$flask at $$15^\circC. $$What is the total pressure of the mixture?

$$P = \frac{nRT}{V} = \frac{(0.0391 + 0.0303) \times 0.08206 \times 288}{1.55} = 1.27\ \text{atm}$$

Q: Given a gas sample with a mass of 0.433 g at $$P = 745 mm Hg $$and $$T = 25^\circC$$, occupying 248 mL, what is the molar mass of the gas?

$$M = \frac{mRT}{PV} = \frac{0.433 \times 0.08206 \times 298}{0.980 \times 0.248} = 43.2\ \text{g/mol}$$

Q: Which of the following is the correct relationship for Dalton's Law of Partial Pressures?

$$P_{\text{total}} = P_A + P_B + P_C + \ldots$$

Q: A 250 mL flask contains 0.10 mol Na2CO3 with 45.0 mL of 6.00 M HCl. What is the limiting reactant and how many moles of CO2 are produced?

Na2CO3 is the limiting reactant; $$0.10\ \text{mol} CO2 is $$produced.

Question 1

A scuba diver holds their breath at sea level (1 atm) with a lung volume of 6.00 L. If the diver descends to a depth where the pressure is 2.5 atm, what will be the new volume of the diver's lungs, assuming temperature remains constant?

Accepted Answer

$$V_2$$ = \frac{$$P_1$$ $$V_1$$}{$$P_2$$} = \frac{1.0 	imes 6.00}{2.5} = 2.4\ 	ext{L}$$

Question 2

Which of the following best describes why a gas takes the shape and volume of its container?

Accepted Answer

Gas particles move independently and spread out to fill the entire volume available.

Question 3

A sample of gas occupies 1.25 L at $$91.3^\circC. $$What will its volume be if it is cooled to $$0.0^\circC at $$constant pressure?

Accepted Answer

$$V_2$$ = $$V_1$$ \frac{$$T_2$$}{$$T_1$$} = 1.25 	imes \frac{273.15}{364.45} = 0.94\ 	ext{L}$$

Question 4

Which of the following is the correct value for the universal gas constant $$R$$ when using pressure in atm and volume in liters?

Accepted Answer

$$R = 0.08206\ 	ext{L} \cdot 	ext{atm} / 	ext{mol} \cdot 	ext{K}$$

Question 5

A 0.448 mole sample of $$N_2$$ gas is placed in a 15.0 L container at 325 K. What is the pressure of the gas?

Accepted Answer

$$P = \frac{nRT}{V} = \frac{0.448 	imes 0.08206 	imes 325}{15.0} = 0.797\ 	ext{atm}$$

Question 6

Which of the following statements about the kinetic molecular theory of gases is FALSE?

Accepted Answer

Gas particles lose energy with every collision with the container walls.

Question 7

A mixture of gases contains 1.25 g of $$O_2$$ and 0.85 g of $$N_2 in a 1.55 L $$flask at $$15^\circC. $$What is the total pressure of the mixture?

Accepted Answer

$$P = \frac{nRT}{V} = \frac{(0.0391 + 0.0303) 	imes 0.08206 	imes 288}{1.55} = 1.27\ 	ext{atm}$$

Question 8

Given a gas sample with a mass of 0.433 g at $$P = 745 mm Hg $$and $$T = 25^\circC$$, occupying 248 mL, what is the molar mass of the gas?

Accepted Answer

$$M = \frac{mRT}{PV} = \frac{0.433 	imes 0.08206 	imes 298}{0.980 	imes 0.248} = 43.2\ 	ext{g/mol}$$

Question 9

Which of the following is the correct relationship for Dalton's Law of Partial Pressures?

Accepted Answer

$$P_{	ext{total}} = P_A + P_B + P_C + \ldots$$

Question 10

A 250 mL flask contains 0.10 mol Na2CO3 with 45.0 mL of 6.00 M HCl. What is the limiting reactant and how many moles of CO2 are produced?

Accepted Answer

Na2CO3 is the limiting reactant; $$0.10\ 	ext{mol} CO2 is $$produced.

Question 11

Which of the following best explains why the pressure of a gas increases when its temperature increases at constant volume?

Accepted Answer

The average kinetic energy of the gas particles increases, causing more frequent and forceful collisions with the container walls.

Question 12

If the partial pressure of $$O_2 in a $$mixture is 187 mm Hg and the total pressure is 526 mm Hg, what is the percent of $$O_2 in $$the mixture by pressure?

Accepted Answer

$$\frac{187}{526} 	imes 100 = 35.6\%$$

Question 13

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

Accepted Answer

Gas particles are attracted to each other by strong forces.

Question 14

A gas has a density of $$2.35\ 	ext{g/L} at$$ $$STP. $$What is its molar mass?

Accepted Answer

$$M = 	ext{density} 	imes 22.4 = 2.35 	imes 22.4 = 52.6\ 	ext{g/mol}$$

Question 15

Which of the following best describes the relationship between the number of moles and the volume of a gas at constant temperature and pressure?

Accepted Answer

The volume is directly proportional to the number of moles.

Question 16

A reaction produces 1.4 L of $$O_2 at 315 K $$and 0.957 atm. How many grams of $$H_2O ($$molar mass = 18.02 g/mol) are required, assuming the reaction is $$2H_2O_2 \rightarrow 2H_2O + O_2$?

Accepted Answer

$$n = \frac{PV}{RT} = \frac{0.957 	imes 1.4}{0.08206 	imes 315} = 0.0518\ 	ext{mol}\ O_2$; 0.0518$$ 	imes 2 = 0.104\ 	ext{mol}\ H_2O_2$$; 0.104$$ 	imes 18.02 = 1.87\ 	ext{g}$$

Question 17

Which of the following is the correct formula for pressure in terms of force and area?

Accepted Answer

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

Chapter 6

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