Q: Convert 2.50 atm to mmHg. (1 atm = 760 mmHg)

$$2.50 \times 760 = 1900\ \mathrm{mmHg}$$

Q: A 5.00 L container holds 2.00 mol of oxygen gas at 300 K. What is the pressure in the container? ($$R = 0.0821\ \mathrm{L\cdot atm\cdot $$mol^{-1}$$\cdot K$$^{-1}$$})$$

$$P = \frac{nRT}{V} = \frac{2.00 \times 0.0821 \times 300}{5.00} = 9.85\ \mathrm{atm}$$

Q: A sample of gas occupies 10.0 L at 1.00 atm and 273 K. What volume will it occupy at 2.00 atm and 273 K?

$$V_2$$ = $$V_1$$ \times \frac{$$P_1$$}{$$P_2$$} = 10.0 \times \frac{1.00}{2.00} = 5.00\ \mathrm{L}$$

Question 1

Which of the following best describes the difference between a solid, liquid, and gas at the molecular level?

Accepted Answer

Solids have molecules in fixed positions, liquids have molecules that slide past each other, and gases have molecules that move independently and rapidly.

Question 2

A sample of ice at $$-10\ ^\circ\mathrm{C} is $$heated at a constant rate. Which segment of the heating curve represents the phase change from solid to liquid?

Accepted Answer

The flat segment at $$0\ ^\circ\mathrm{C}.$$

Question 3

Which intermolecular force is primarily responsible for the high boiling point of water?

Accepted Answer

Hydrogen bonding

Question 4

Which of the following substances would you expect to have the lowest vapor pressure at room temperature?

Accepted Answer

Water ($$\mathrm{H_2O})$$

Question 5

A phase change diagram shows a substance being heated from solid to gas. At which points does the temperature remain constant?

Accepted Answer

During the melting and boiling transitions

Question 6

Which of the following best explains why salt is spread on icy roads in winter?

Accepted Answer

Salt decreases the freezing point of water, causing ice to melt.

Question 7

Convert 2.50 atm to mmHg. (1 atm = 760 mmHg)

Accepted Answer

$$2.50 	imes 760 = 1900\ \mathrm{mmHg}$$

Question 8

Which of the following statements about ideal and real gases is correct?

Accepted Answer

Ideal gases have no intermolecular forces and occupy no volume.

Question 9

A 5.00 L container holds 2.00 mol of oxygen gas at 300 K. What is the pressure in the container? ($$R = 0.0821\ \mathrm{L\cdot atm\cdot $$mol^{-1}$$\cdot K$$^{-1}$$})$$

Accepted Answer

$$P = \frac{nRT}{V} = \frac{2.00 	imes 0.0821 	imes 300}{5.00} = 9.85\ \mathrm{atm}$$

Question 10

A sample of gas occupies 10.0 L at 1.00 atm and 273 K. What volume will it occupy at 2.00 atm and 273 K?

Accepted Answer

$$V_2$$ = $$V_1$$ 	imes \frac{$$P_1$$}{$$P_2$$} = 10.0 	imes \frac{1.00}{2.00} = 5.00\ \mathrm{L}$$

Question 11

Which of the following best describes why a balloon filled with helium rises in air?

Accepted Answer

Helium is less dense than air, so the balloon rises.

Question 12

Which of the following is a colligative property?

Accepted Answer

Boiling point elevation

Question 13

A solution is prepared by dissolving 58.5 g of NaCl in 1.00 kg of water. What is the molality of the solution? (Molar mass of NaCl = 58.5 g/mol)

Accepted Answer

$$m = \frac{1.00\ \mathrm{mol}}{1.00\ \mathrm{kg}} = 1.00\ \mathrm{mol/kg}$$

Question 14

Which of the following gases would deviate most from ideal behavior under high pressure and low temperature?

Accepted Answer

Ammonia

Question 15

A laboratory experiment requires you to collect 0.500 mol of CO$$_2$$ gas at 25$$^\circC $$and 1.00 atm. What volume will the gas occupy? ($$R = 0.0821\ \mathrm{L\cdot atm\cdot $$mol^{-1}$$\cdot K$$^{-1}$$})$$

Accepted Answer

$$V = \frac{nRT}{P} = \frac{0.500 	imes 0.0821 	imes 298}{1.00} = 12.2\ \mathrm{L}$$

Question 16

Which of the following best explains why water boils at a lower temperature at higher altitudes?

Accepted Answer

Atmospheric pressure is lower, so water molecules require less energy to escape into the gas phase.

Question 17

Which of the following is NOT a property of gases?

Accepted Answer

They have definite shape and volume.

Question 18

A gas sample is collected over water at 25$$^\circC $$and 1.00 atm. The vapor pressure of water at 25$$^\circC is 23.8 $$mmHg. What is the partial pressure of the dry gas? (1 atm = 760 mmHg)

Accepted Answer

$$P_{	ext{gas}} = 760 - 23.8 = 736.2\ \mathrm{mmHg}$$

Question 19

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

Accepted Answer

As temperature increases, the average kinetic energy of gas molecules increases.

Unit 5 CHEM 1 Test Study Guidance

Study Guide - Practice Questions

Study Guide - Flashcards