Q: A 6.0 L cylinder contains a gas at 4.0 atm. If the pressure is reduced to 1.0 atm at constant temperature, what is the new volume of the gas? Use Boyle's Law.

$$V_2$$ = \frac{$$V_1$$ $$P_1$$}{$$P_2$$} = \frac{6.0 \times 4.0}{1.0} = 24\ \text{L}$$

Q: A sample of gas has a volume of 2.80 L at an unknown temperature. When submerged in ice water at $$0\ ^\circ\text{C}$$, its volume decreases to 2.57 L. What was its initial temperature in kelvins?

$$T_1$$ = \frac{$$V_1$$}{$$V_2$$} \times $$T_2$$ = \frac{2.80}{2.57} \times 273 = 297\ \text{K}$$

Q: Calculate the volume occupied by 0.845 mol of nitrogen gas at a pressure of 1.37 atm and temperature of 315 K. ($$R = 0.082058\ \text{L atm K}^{-1}\text{mol}^{-1})$$

$$V = \frac{nRT}{P} = \frac{0.845 \times 0.082058 \times 315}{1.37} = 15.9\ \text{L}$$

Question 1

Which of the following statements best describes the compressibility and homogeneity of gases compared to solids and liquids?

Accepted Answer

Gases are highly compressible and homogeneous, unlike solids and liquids.

Question 2

A 6.0 L cylinder contains a gas at 4.0 atm. If the pressure is reduced to 1.0 atm at constant temperature, what is the new volume of the gas? Use Boyle's Law.

Accepted Answer

$$V_2$$ = \frac{$$V_1$$ $$P_1$$}{$$P_2$$} = \frac{6.0 	imes 4.0}{1.0} = 24\ 	ext{L}$$

Question 3

Which property is NOT one of the four variables used to describe a gaseous state?

Accepted Answer

Density (d)

Question 4

A sample of gas has a volume of 2.80 L at an unknown temperature. When submerged in ice water at $$0\ ^\circ	ext{C}$$, its volume decreases to 2.57 L. What was its initial temperature in kelvins?

Accepted Answer

$$T_1$$ = \frac{$$V_1$$}{$$V_2$$} 	imes $$T_2$$ = \frac{2.80}{2.57} 	imes 273 = 297\ 	ext{K}$$

Question 5

Which law explains why the volume of a balloon decreases when the temperature drops, assuming pressure and amount of gas are constant?

Accepted Answer

Charles's Law

Question 6

A 4.8 L sample of helium gas contains 0.22 mol of helium. How many additional moles must be added to reach a volume of 6.4 L at constant temperature and pressure?

Accepted Answer

$$n_2$$ = \frac{$$V_2$$}{$$V_1$$} $$n_1$$ = \frac{6.4}{4.8} 	imes 0.22 = 0.29\ 	ext{mol}$$; 	ext{mol to add} = 0.29 - 0.22 = 0.07\ 	ext{mol}$

Question 7

Which of the following is the correct form of the Combined Gas Law?

Accepted Answer

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

Question 8

Calculate the volume occupied by 0.845 mol of nitrogen gas at a pressure of 1.37 atm and temperature of 315 K. ($$R = 0.082058\ 	ext{L atm K}^{-1}	ext{mol}^{-1})$$

Accepted Answer

$$V = \frac{nRT}{P} = \frac{0.845 	imes 0.082058 	imes 315}{1.37} = 15.9\ 	ext{L}$$

Question 9

Which of the following best describes Dalton’s Law of Partial Pressures?

Accepted Answer

The total pressure exerted by a mixture of gases is the sum of the partial pressures of each individual gas.

Question 10

A 2 L flask contains $$1.25 	imes 10$$^{-3}$$ mol O_2$ and 3.25$$ 	imes $$10^{-3}$$ mol He at 15°C. What is the total pressure in the flask? ($$R = 0.08206\ 	ext{L atm K}^{-1}	ext{mol}^{-1})$$

Accepted Answer

$$P_T = \frac{(n_{O_2$} + n_{He})RT}{V} = \frac{(0.00125 + 0.00325) 	imes 0.08206 	imes 288}{2.00} = 0.53\ 	ext{atm}$$

Question 11

Which statement about the kinetic-molecular theory of gases is correct?

Accepted Answer

The average kinetic energy of gas molecules is proportional to temperature.

Question 12

Which of the following is a correct real-world application of 'like dissolves like'?

Accepted Answer

Salt dissolves in water because both are polar substances.

Question 13

Which of the following is NOT a property of a solution?

Accepted Answer

Components can be separated by filtration.

Question 14

A solution is prepared by dissolving 225 g of glucose ($$C_6H_{12}O_6$) in enough water to make 825 mL of solution. What is the molarity? (Molar mass of glucose = 180 g/mol)

Accepted Answer

$$M = \frac{225}{180} \div 0.825 = 1.51\ 	ext{M}$$

Question 15

Which statement correctly describes the behavior of strong electrolytes in water?

Accepted Answer

Strong electrolytes dissociate completely into ions and conduct electricity well.

Question 16

What is the molar mass of a gas if 98 mL of it weighs 0.081 g at STP? ($$R = 8.31\ 	ext{kPa L K}^{-1}	ext{mol}^{-1}$$, $$P = 100\ 	ext{kPa}$$, $$T = 273\ 	ext{K})$$

Accepted Answer

$$n = \frac{PV}{RT} = \frac{100 	imes 0.098}{8.31 	imes 273} = 0.00431\ 	ext{mol}$$; 	ext{Molar mass} = \frac{0.081}{0.00431} = 18.79\ 	ext{g/mol}$

Question 17

Which of the following best explains why ionic compounds conduct electricity in aqueous solution?

Accepted Answer

Ions dissociate in water and are surrounded by water molecules, allowing them to transport electric charge.

Gaseous States and Solutions: Properties, Laws, and Behavior

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