Answers25-26 CHEMISTRY IN THE EARTH SYSTEM S1Temperature and Heat

Temperature and Heat — Unit test Answers

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1
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In the heat equation, what does Q represent?

A
heat required to raise the temperature
B
specific heat of the substance
C
mass of the substance
D
change in temperature
2
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According to the first law of thermodynamics, what could happen when heat is added to a system?

A
The internal energy of the system decreases.
B
The heat is turned into work done by the system.
C
New energy is created within the system.
D
Some of the energy in the system is destroyed.
3

Substance X transfers thermal energy to substance Y through conduction. What is an accurate conclusion about the condition of both substances before conduction occurred?

A
Their molecules had the same amount of energy.
B
The substances were the same temperature.
C
Substance X’s molecules were faster than substance Y’s.
D
Substance X was cooler than substance Y.
4

A substance has a specific heat of 0.870 J/g°C. It requires 2,000.0 joules to increase the temperature of 10.0 grams of the substance from its original temperature to its final temperature.

A
87.0°C
B
174°C
C
230°C
D
1,740°C
5

Which is the best example of decreasing entropy?

A
A box of nails is left in the rain and the nails rust over time.
B
A pile of dirt on a floor is cleaned up with a broom.
C
A puddle of water is exposed to the sun and evaporates.
D
A tree in a forest grows naturally over 10 years.
6

The chart shows the temperatures of four different substances.

Question illustration
A
15
B
18
C
20
D
25
7

Which best describes the relationship between internal energy and thermal energy?

A
Thermal energy is a measure of the internal energy of a substance.
B
Internal energy is a measure of the thermal energy of a substance.
C
Internal energy is the portion of thermal energy that can be transferred.
D
Thermal energy is the portion of internal energy that can be transferred.
8

In an aerosol can used for spray paint, a highly compressed "propellant” helps move the liquid into a "dip tube” so that it can be sprayed out. The valve through which the liquid sprays is usually closed, but when it is pressed down, it opens and allows material to pass through.

Question illustration
A
The propellant gas wants to expand as much as it can, so if the valve is open, the propellant expands and pushes the spray up out of the can making more room for itself to expand.
B
The liquid spray wants to expand as much as it can, so when the valve is opened, it naturally moves up through the tube, leaving behind the propellant gas that was holding it back.
C
The compressed gas is able to reverse the force of gravity because gravity does not work on atoms that are far apart. So when the force is reversed, the spray moves up instead of down.
D
The valve allows air into the can, and since air is expandable, it comes into the can and pushes out the propellant and spray that had been in the can before.
9

The diagram shows an engine piston before and after heat is added, which illustrates the laws of thermodynamics.

Question illustration
A
W
B
X
C
Y
D
Z
10

How much heat is needed to vaporize 10.00 grams of water at 100.0°C? The latent heat of vaporization of water is 2,259 J/g.

A
22.59 J
B
1,000 J
C
2,269 J
D
22,590 J
11

What happens at the flat areas of a substance’s heating curve?

A
Both the average kinetic energy of the molecules and the temperature remain the same.
B
The average kinetic energy of the molecules increases, and the temperature remains the same.
C
The average kinetic energy of the molecules decreases, and the temperature increases.
D
Both the average kinetic energy of the molecules and the temperature decrease.
12

Suppose the exhaust system on a heat engine is not functioning properly. Which statement best explains how this will affect the engine?

A
The temperature of the gas will not increase during the compression stage.
B
Burned gases will not be released into the surrounding air.
C
The fuel-air mixture will not be able to enter the cylinder.
D
Combustion and subsequent gas expansion will not occur.
13

Jin knows that the initial internal energy of a closed system is 78 J and the final internal energy is 180 J. He also knows that 64 J of energy are used to do work. To find the heat added to the system, Jin completes the steps below.1. Add the initial internal energy plus the final internal energy to find the change in internal energy. 2. Add the change in internal energy to the energy used to do work.3. Write the answer in joules.

A
For step 1, he should have used 180 J as the change in internal energy.
B
For step 1, he should have subtracted 78 J from 180 J to find the change in internal energy.
C
For step 2, he should have subtracted the change in internal energy from the energy used to do work.
D
For step 2, he should have subtracted the energy used to do work from the change in internal energy.
14

Allen made a diagram to compare radiation and conduction.

Question illustration
M
Must involve temperature differences between substances or objects
O
Occurs when molecules are in direct contact
I
Involves the movement of fluids based on density differences
C
Can occur where there is little or no matter
15

Chen explained that heat engines illustrate only the second law of thermodynamics because they involve the flow of thermal energy from hot to cool areas. His friend Mia disagreed and explained that these engines illustrate only the first law of thermodynamics because they are sometimes 100 percent efficient if they conserve enough energy.

A
Chen is incorrect because heat engines illustrate only the first law of thermodynamics.
B
Chen is incorrect because in heat engines thermal energy flows from cool to warm areas.
C
Mia is incorrect because heat engines illustrate only the second law of thermodynamics.
D
Mia is incorrect because machines and engines can never be 100 percent efficient.

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