Q: A 177 g sample of copper cools from 155°C to 23°C. The specific heat of copper is $$0.385 \ \mathrm{J/g$$^{\circ}$$C}. $$What is the heat given off?

$$Q = 177 \times 0.385 \times (23 - 155) = -8998.14 \ \mathrm{J}$$

Q: A 5.00 g piece of Pb at 75.0°C loses 32 Joules of heat to its surroundings. The specific heat of Pb is $$0.128 \ \mathrm{J/g$$^{\circ}$$C}. $$What is the final temperature of the Pb?

$$T_f = 75.0 - \frac{32}{5.00 \times 0.128} = 25.0$$^{\circ}$$C$$

Question 1

Which of the following best describes a homogeneous mixture?

Accepted Answer

A mixture in which the composition is uniform throughout, such as salt water.

Question 2

Which of the following is an example of a chemical property?

Accepted Answer

Flammability of gasoline

Question 3

A student mixes sand and water in a beaker. What type of mixture is formed?

Accepted Answer

Heterogeneous mixture (suspension)

Question 4

Which of the following best explains why the temperature does not change during a phase change, even though heat is still being added?

Accepted Answer

The added heat is used to overcome intermolecular forces, increasing potential energy.

Question 5

Which of the following particle diagrams best represents a compound?

Accepted Answer

A diagram showing two or more different atoms bonded together in fixed ratios.

Question 6

Which of the following changes is a chemical change?

Accepted Answer

Fireworks explode in the sky.

Question 7

A 177 g sample of copper cools from 155°C to 23°C. The specific heat of copper is $$0.385 \ \mathrm{J/g$$^{\circ}$$C}. $$What is the heat given off?

Accepted Answer

$$Q = 177 	imes 0.385 	imes (23 - 155) = -8998.14 \ \mathrm{J}$$

Question 8

Which statement correctly compares heat and temperature?

Accepted Answer

Heat is the transfer of thermal energy; temperature is the measure of average kinetic energy.

Question 9

Which of the following best describes the difference between a suspension and a colloid?

Accepted Answer

A suspension has particles that settle out over time, while a colloid has particles that remain dispersed.

Question 10

During an endothermic reaction, what happens to the kinetic and potential energy of the system?

Accepted Answer

Kinetic energy increases, potential energy increases.

Question 11

A 5.00 g piece of Pb at 75.0°C loses 32 Joules of heat to its surroundings. The specific heat of Pb is $$0.128 \ \mathrm{J/g$$^{\circ}$$C}. $$What is the final temperature of the Pb?

Accepted Answer

$$T_f = 75.0 - \frac{32}{5.00 	imes 0.128} = 25.0$$^{\circ}$$C$$

Question 12

Which of the following is a physical property?

Accepted Answer

Malleability

Question 13

Which of the following best describes a pure substance?

Accepted Answer

A material with a fixed composition and distinct chemical properties.

Question 14

Which of the following is an example of a solution?

Accepted Answer

Salt water

Question 15

If 37,000 J of heat is added to a sample of ice at -10°C which is completely melted, what is the mass of the ice? ($$c_{ice} = 2.09 \ \mathrm{J/g$$^{\circ}$$C}$$, $$c_{water} = 4.184 \ \mathrm{J/g$$^{\circ}$$C}$$, $$\Delta H_{fus} = 334 \ \mathrm{J/g})$$

Accepted Answer

$$m = \frac{37,000}{2.09 	imes 10 + 334 + 4.184 	imes 0} \approx 104.3 \ \mathrm{g}$$

Question 16

Which of the following statements about latent heat of vaporization and fusion is correct?

Accepted Answer

Latent heat of vaporization is much larger than latent heat of fusion.

Question 17

Which of the following best describes the energy changes during melting?

Accepted Answer

Potential energy increases, kinetic energy remains constant.

Question 18

Which of the following is NOT a mixture?

Accepted Answer

Carbon dioxide ($$CO_2)$$

Question 19

Which of the following best explains why water requires more energy to vaporize than to melt?

Accepted Answer

Breaking intermolecular forces in vaporization requires far more energy than loosening them in melting.

Question 20

Which of the following is an example of a heterogeneous mixture?

Accepted Answer

Mud water

Introduction to Chemistry: Classification of Matter, Properties, and Energy Changes

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