Question 1

Which of the following equations correctly expresses the amount of heat required to change the temperature of a substance with mass $$m$$, specific heat $$c$$, and temperature change $$\Delta T$$?

Accepted Answer

$$Q = mc\Delta T$$

Question 2

A 0.5 kg sample of water at 20$$^\circC is $$placed in a freezer and cooled to $$-5^\circC$$, forming ice. Which of the following steps is NOT required to calculate the total energy removed?

Accepted Answer

Calculating the energy required to vaporize the water

Question 3

Which formula gives the heat required to melt a mass $$m of a $$substance with latent heat of fusion $$L$$?

Accepted Answer

$$Q = mL$$

Question 4

A 250 L cylinder of xenon gas at 20$$^\circC $$and 5.0 atm is heated to 50$$^\circC at $$constant volume. Treating xenon as a monatomic ideal gas, which equation should be used to calculate the heat required?

Accepted Answer

$$Q = nC_V\Delta T$$

Question 5

Which of the following best describes the difference between an open, closed, and isolated calorimeter system?

Accepted Answer

An isolated system does not allow mass or energy exchange; a closed system allows energy but not mass exchange; an open system allows both.

Question 6

A 0.55 kg sample of an unknown metal is heated to 75$$^\circC $$and placed in 0.5 kg of water at 15$$^\circC. $$The final equilibrium temperature is 18.8$$^\circC. If $$the specific heat of water is $$4186 \ \frac{J}{kg \cdot K}$$, which equation would you use to find the specific heat of the metal?

Accepted Answer

$$m_{metal}c$$_{metal}(T_{final} - T_{initial,metal}) + $$m_{water}c$$_{water}(T_{final} - T_{initial,water}) = 0$$

Question 7

Which of the following is the correct expression for the rate of heat transfer by conduction through a material of thermal conductivity $$k$$, cross-sectional area $$A$$, length $$L$$, and temperature difference $$T_1$$ - $$T_2$$?

Accepted Answer

$$\frac{Q}{t} = \frac{kA(T_1$ - T_2$)}{L}$$

Question 8

A 4.0 g sample of steam at 100$$^\circC $$condenses on a burn victim's skin and cools to 45$$^\circC. $$Which process releases more heat: condensation of steam or cooling of water from 100$$^\circC to 45$^\circC$$?

Accepted Answer

Condensation of steam releases more heat.

Question 9

Which of the following is the correct formula for the rate of heat transfer by radiation from a surface with emissivity $$\epsilon$$, area $$A$$, and temperatures $$T_1 ($$object) and $$T_2 ($$environment)?

Accepted Answer

$$\frac{Q}{t} = \epsilon \sigma A (T_1$^4 - T_2$^4)$$

Question 10

During a phase change, such as melting or boiling, which of the following statements is true?

Accepted Answer

The temperature remains constant while heat is added or removed.

Question 11

A copper rod is used to melt a 25 g ice cube at 0$$^\circC. If $$the rod is 37 cm long and 7.5 cm in diameter, and the hot plate is at 320$$^\circC$$, which equation would you use to find the time required to melt the ice?

Accepted Answer

$$t = \frac{mL}{\frac{Q}{t}}$$

Question 12

Which of the following best describes the physical meaning of the specific heat capacity $$c of a $$substance?

Accepted Answer

The amount of heat required to raise the temperature of 1 kg of the substance by 1 K.

Question 13

Which of the following is true for an isolated calorimeter system during a heat exchange experiment?

Accepted Answer

$$Q_{in} - Q_{out} = 0$$

Question 14

A 0.2 kg sample of water at 25$$^\circC is $$mixed with 0.1 kg of ice at $$-15^\circC. $$Which of the following steps is NOT necessary to determine the final temperature?

Accepted Answer

Calculating the energy required to vaporize the water

Question 15

Which of the following is the correct value for the molar specific heat at constant volume $$C_V$$ for a monatomic ideal gas?

Accepted Answer

$$C_V = \frac{3}{2}R$$

Question 16

Which process is responsible for the transfer of heat by the bulk movement of a fluid?

Accepted Answer

Convection

Question 17

A 0.5 kg sample of water at 20$$^\circC is to be $$turned into ice at $$-5^\circC. $$Which of the following is the correct sequence of energy calculations?

Accepted Answer

Cool water to 0$$^\circC$$, freeze at 0$$^\circC$$, cool ice to $$-5^\circC$$

Heat and Calorimetry II: Specific Heat, Phase Changes, and Heat Transfer

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