Deck 19: Heat and the First Law of Thermodynamics

Question 1

The direction of heat flow between two objects depends on the amount of internal energy each of the objects has.

Answer 1

False

Question 2

The heat required to change a substance from the solid to the liquid state is referred to as the

A)heat of fusion.
B)heat of vaporization.
C)heat of melting.
D)heat of freezing.
E)heat of condensation.

Answer 2

heat of fusion.

Question 3

It is a well-known fact that water has a higher specific heat capacity than iron. Now, consider equal masses of water and iron that are initially in thermal equilibrium. The same amount of heat, 30 calories, is added to each. Which statement is true?

A)They remain in thermal equilibrium.
B)They are no longer in thermal equilibrium; the iron is warmer.
C)They are no longer in thermal equilibrium; the water is warmer.
D)It is impossible to say without knowing the exact mass involved.
E)It is impossible to say without knowing the exact specific heat capacities.

Answer 3

They are no longer in thermal equilibrium; the iron is warmer.

Question 4

Distinguish between heat, internal energy, and temperature.

Question 5

A thermally isolated system is made up of a hot piece of aluminum and a cold piece of copper; the aluminum and the copper are in thermal contact. The specific heat capacity of aluminum is more than double that of copper. Which object experiences the greater temperature change during the time the system takes to reach thermal equilibrium?

A)the copper
B)the aluminum
C)neither; both experience the same size temperature change
D)it is impossible to tell without knowing the masses
E)it is impossible to tell without knowing the volumes

Question 6

A cup of water is scooped up from a swimming pool of water. Compare the temperature T and the internal energy U of the water, in both the cup and the swimming pool.

A)T_Pool is greater than T_Cup, and the U is the same.
B)T_Pool is less than T_Cup, and the U is the same.
C)T_Pool is equal to T_Cup, and U_Pool is greater than U_Cup.
D)T_Pool is equal to T_Cup, and U_Pool is less than U_Cup.
E)T_Pool is equal to T_Cup, and U_Pool is equal to U_Cup.

Question 7

Conductive heat transfer can only occur if solids mediate the energy transfer.

Question 8

Convective heat transfer can only occur if fluids mediate the energy transfer.

Question 9

The heat required to change a substance from the liquid to the vapor state is referred to as the

A)heat of fusion.
B)heat of vaporization.
C)heat of evaporation.
D)heat of condensation.
E)heat of melting.

Question 10

The internal energy of an ideal gas is changed by adding heat Q to the system and also by doing work W on the gas. What is the change in internal energy of the gas?

A)4.186Q - W
B)Q - 4.186W
C)W - Q
D)Q + W
E)Q - W

Question 11

Is it possible to transfer heat from a cold reservoir to a hot reservoir?

A)No.
B)Yes; this will happen naturally.
C)Yes, but work will have to be done.
D)Theoretically yes, but it hasn't been accomplished yet.

Question 12

State the First Law of Thermodynamics.

Question 13

A thermally isolated system is made up of a hot piece of aluminum and a cold piece of copper; the aluminum and the copper are in thermal contact. The specific heat capacity of aluminum is more than double that of copper. Which object experiences the greater magnitude gain or loss of heat during the time the system takes to reach thermal equilibrium?

A)the aluminum
B)the copper
C)neither; both experience the same size gain or loss of heat
D)it is impossible to tell without knowing the masses
E)it is impossible to tell without knowing the volumes

Question 14

Radiative heat transfer requires a fluid to mediate the energy transfer.

Question 15

In the first law of thermodynamics, Q is the heat gained by the system, that is, Q is positive if the system gains heat.

Question 16

Describe the technique know as calorimetry.

Question 17

FIGURE 19-1
The process shown on the T-V graph in Fig. 19-1 is an

A)adiabatic compression.
B)isothermal compression.
C)isochoric compression.
D)isobaric compression.
E)isovolumetric compression.

Question 18

In the first law of thermodynamics, W is the work done on the system, that is, W is positive if work is done on the system.

Question 19

A chunk of ice (T = -20°C) is added to a thermally insulated container of cold water (T = 0°C). What happens in the container?

A)The ice melts until thermal equilibrium is established.
B)The water cools down until thermal equilibrium is established.
C)Some of the water freezes and the chunk of ice gets larger.
D)none of the above

Question 20

Is it possible to transfer heat from a hot reservoir to a cold reservoir?

A)No.
B)Yes; this will happen naturally.
C)Yes, but work will have to be done.
D)Theoretically yes, but it hasn't been accomplished yet.

Question 21

When the first law of thermodynamics, Q = ΔU + W, is applied to an ideal gas that is taken through an adiabatic process,

A)ΔU = 0.
B)W = 0.
C)Q = 0.
D)all of the above
E)none of the above

Question 22

When the first law of thermodynamics, Q = ΔU + W, is applied to an ideal gas that is taken through an isothermal process,

A)ΔU = 0
B)W = 0
C)Q = 0
D)all of the above
E)none of the above

Question 23

Consider two cylinders of gas identical in all respects except that one contains O₂ and the other He. Both hold the same volume of gas at STP and are closed by a movable piston at one end. Both gases are now compressed adiabatically to one-third their original volume. Which gas will show the greater temperature increase?

A)the O₂
B)the He
C)Neither; both will show the same increase.
D)It's impossible to tell from the information given.

Question 24

During which type of process applied to an ideal gas is there no work done by the gas?

A)adiabatic
B)isothermal
C)isochoric
D)isobaric
E)Work is done by the gas during any change to the gas.

Question 25

When a gas expands adiabatically,

A)the internal energy of the gas decreases.
B)the internal energy of the gas increases.
C)there is no work done by the gas.
D)work is done on the gas.
E)heat flows out of the system.

Question 26

When the first law of thermodynamics, Q = ΔU + W, is applied to an ideal gas that is taken through an isochoric process,

A)ΔU = 0.
B)W = 0.
C)Q = 0.
D)all of the above
E)none of the above

Question 27

In an isobaric process, there is no change in

A)pressure.
B)temperature.
C)volume.
D)internal energy.
E)heat.

Question 28

FIGURE 19-3
The process shown on the PV diagram in Fig. 19-3 is

A)adiabatic.
B)isothermal.
C)isochoric.
D)isobaric.
E)idealistic.

Question 29

The process whereby heat flows by the mass movement of molecules from one place to another is referred to as

A)conduction.
B)convection.
C)radiation.
D)inversion.
E)evaporation.

Question 30

In an isochoric process, there is no change in

A)pressure.
B)temperature.
C)volume.
D)internal energy.
E)heat.

Question 31

When the first law of thermodynamics, Q = ΔU + W, is applied to an ideal gas that is taken through an isobaric process,

A)ΔU = 0.
B)W = 0.
C)Q = 0.
D)all of the above
E)none of the above

Question 32

The process whereby heat flows in the absence of any medium is referred to as

A)conduction.
B)convection.
C)radiation.
D)inversion.
E)evaporation.

Question 33

The process whereby heat flows by means of molecular collisions is referred to as

A)conduction.
B)convection.
C)radiation.
D)inversion.
E)evaporation.

Question 34

During which type of process applied to an ideal gas is there no change in internal energy of the gas?

A)isobaric
B)isothermal
C)isochoric
D)adiabatic
E)Internal energy changes during any of these processes.

Question 35

An ideal gas starts in state A at temperature T. The gas expands to new volume V by an adiabatic process and its final temperature is Tʹ. What is the relationship between T and Tʹ?

A)T = Tʹ
B)T > Tʹ
C)T < Tʹ
D)The answer depends on the heat capacity of the ideal gas.
E)The answer depends on the number of moles of gas and the pressure.

Question 36

FIGURE 19-2
The process shown on the PV diagram in Fig. 19-2 is an

A)adiabatic expansion.
B)isothermal expansion.
C)isometric expansion.
D)isobaric expansion.
E)isovolumetric compression.

Question 37

In an isothermal process, there is no change in

A)pressure.
B)temperature.
C)volume.
D)heat.
E)internal energy.

Question 38

During which type of process applied to an ideal gas is there no heat added to the gas?

A)isobaric
B)isochoric
C)isothermal
D)adiabatic
E)A and C

Question 39

A gas is quickly compressed in an isolated environment. During the event, the gas exchanged no heat with its surroundings. This process is

A)isothermal.
B)isochoric.
C)isobaric.
D)adiabatic.
E)idealistic.

Question 40

Consider two cylinders of gas identical in all respects except that one contains O₂ and the other He. Both hold the same volume of gas at STP and are closed by a movable piston at one end. Both gases are now compressed adiabatically to one-third their original volume. Which gas will show the greater pressure increase?

A)the O₂
B)the He
C)Neither; both will show the same increase.
D)It's impossible to tell from the information given.

Question 41

The melting point of aluminum is 660°C, the latent heat of fusion is 4.0 × 10⁵ J/kg and its specific heat is 900 J/(kg∙K). How much heat must be added to 500 g of aluminum at 27°C to completely melt it?

A)485 kJ
B)395 kJ
C)273 kJ
D)147 kJ
E)14 kJ

Question 42

A camper is about to drink his morning coffee. He pours 400 grams of coffee, initially at 75.0°C, into a 250-g aluminum cup, initially at 16.0°C. What is the equilibrium temperature of the coffee-cup system, assuming no heat is lost to the surroundings? The specific heat of aluminum is 900 J/(kg∙K). Assume that the specific heat of coffee is the same as the specific heat of water.

A)45.5°C
B)62.0°C
C)65.0°C
D)68.0°C
E)71.0°C

Question 43

An insulated container is filled with a mix of 400 g of water at 20.0°C and 60 g of ice at 0.00°C. Assuming negligible heat is exchanged with the container, what is the temperature of the mixture when it reaches thermal equilibrium?

A)7.0°C
B)6.0°C
C)0.0°C
D)4.0°C
E)5.0°C

Question 44

The type of heat transfer that occurs between a stove and a pot placed on it is

A)convective.
B)conductive.
C)radiative.
D)countercurrent.
E)evaporation.

Question 45

The type of heat transfer that occurs between the radiator of a car and the atmosphere, when the car is in motion, is principally

A)convective.
B)conductive.
C)radiative.
D)countercurrent.
E)evaporation.

Question 46

How much heat must be removed from 456 g of water at 25.0°C to change it into ice at -10.0°C? The specific heat of ice is 2090 J/(kg∙K) and the latent heat of fusion of water is 33.5 × 10⁴ J/kg.

A)105 kJ
B)153 kJ
C)57.3 kJ
D)47.7 kJ
E)210 kJ

Question 47

A 425-g piece of metal at 100°C is dropped into a 100-g aluminum cup containing 500 g of water at 15°C. The final temperature of the system is 40°C. What is the specific heat of the metal, assuming no heat is exchanged with the surroundings? The specific heat of aluminum is 900 J/(kg∙K).

A)1900 J/(kg∙K)
B)2140 J/(kg∙K)
C)3300 J/(kg∙K)
D)3800 J/(kg∙K)
E)4280 J/(kg∙K)

Question 48

If 40 kcal of heat is added to 2.0 kg of water, what is the resulting temperature change?

A)80C°
B)60C°
C)40C°
D)20C°
E)0.05C°

Question 49

330 g of water at 55°C are poured into an 855 g aluminum container with an initial temperature of 10°C. The specific heat of aluminum is 900 J/(kg∙K). What is the final temperature of the system, assuming no heat is exchanged with the surroundings?

A)28°C
B)39°C
C)31°C
D)33°C
E)35°C

Question 50

150 kcal of heat raises the temperature of 2.0 kg of material by 400 F°. What is the material's specific heat capacity?

A)1.35 kcal/kg∙C°
B)1.31 kcal/kg∙C°
C)0.75 kcal/kg∙C°
D)0.34 kcal/kg∙C°
E)0.19 kcal/kg∙C°

Question 51

An athlete doing push-ups performs 650 kJ of work and loses 425 kJ of heat. What is the change in the internal energy of the athlete?

A)-225 kJ
B)-1075 kJ
C)1075 kJ
D)225 kJ
E)276 kJ

Question 52

The type of heat transfer that occurs between warm food and the air in the room is principally

A)convective.
B)conductive.
C)radiative.
D)countercurrent.
E)evaporation.

Question 53

Convection can occur

A)only in solids.
B)only in liquids.
C)only in gases.
D)only in liquids and gases.
E)in solids, liquids, and gases.

Question 54

The type of heat transfer that occurs between a heating lamp and the food that it is keeping warm is

A)convective.
B)conductive.
C)radiative.
D)countercurrent.
E)evaporation.

Question 55

How much heat is required to change 456 g of ice at -25.0°C into water at 25.0°C? The specific heat of ice is 2090 J/(kg∙K)and the latent heat of fusion of water is 33.5 × 10⁴ J/kg.

A)224 kJ
B)153 kJ
C)112 kJ
D)71.5 kJ
E)72.5 kJ

Question 56

A 50.0-g sample of a material at 80.0°C is dropped into a calorimeter containing 100.0 g of water at 20.0°C. When the mixture reaches thermal equilibrium, it is at a temperature 24.0°C. If heat transfer to the walls of the calorimeter is negligible, what is the specific heat of the material?

A)0.143 cal/(g∙C°)
B)0.322 cal/(g∙C°)
C)0.221 cal/(g∙C°)
D)0.437 cal/(g∙C°)
E)0.0714 cal/(g∙C°)

Question 57

Ice has a latent heat of fusion of 80 kcal/kg. How much heat is required to melt 200 g of ice?

A)400 J
B)160 J
C)67 kJ
D)32 kJ
E)16 kJ

Question 58

By what primary heat transfer mechanism does one end of an iron bar become hot when the other end is placed in a flame?

A)natural convection
B)conduction
C)radiation
D)forced convection
E)countercurrent.

Question 59

A 400-g piece of metal at 100°C is dropped into a cup containing 450 g of water at 15.0°C. The final temperature of the system is 40.0°C. What is the specific heat of the metal, assuming no heat is exchanged with the surroundings or the cup?

A)1960 J/(kg∙K)
B)2830 J/(kg∙K)
C)3420 J/(kg∙K)
D)3780 J/(kg∙K)
E)4280 J/(kg∙K)

Question 60

A person tries to heat up her bath water by adding 5.0 L of water at 80°C to 60 L of water at 30°C. What is the final temperature of the water?

A)34°C
B)36°C
C)38°C
D)40°C
E)65°C

Question 61

A person makes ice tea by adding ice to 1.8 kg of hot tea, initially at 80°C. How many kilograms of ice, initially at 0°C, are required to bring the mixture to 10°C?

A)1.0 kg
B)1.2 kg
C)1.4 kg
D)1.5 kg
E)1.7 kg

Question 62

During an isothermal process, 5.0 J of heat is removed from an ideal gas. What is the change in internal energy?

A)zero
B)2.5 J
C)5.0 J
D)7.5 J
E)10 J

Question 63

How much heat energy is needed to change 10 kg of water at 50°C to steam at 120°C?

A)4.2 × 10⁵ J
B)2.3 × 10⁷ J
C)4.2 × 10⁶ J
D)3.6 × 10⁶ J
E)2.5 × 10⁷ J

Question 64

During an isothermal process, 5.0 J of heat is removed from an ideal gas. What is the work done in the process?

A)zero
B)2.0 J
C)5.0 J
D)-5.0 J
E)none of the above

Question 65

An ideal gas undergoes an adiabatic process while doing 25 J of work. What is the change in internal energy?

A)zero
B)50 J
C)25 J
D)-25 J
E)none of the above

Question 66

200 g of ice at 0°C is dropped into a calorimeter of negligible heat capacity containing 350 g of water at 20°C. What is the temperature of the system when it reaches equilibrium? The latent heat of fusion of water is 80 cal/g.

A)0°C
B)24°C
C)-13°C
D)13°C
E)-24°C

Question 67

If 2.0 kg of water at 0°C is to be vaporized, how much heat must be added?

A)1080 cal
B)1080 kcal
C)1140 cal
D)1280 cal
E)1280 kcal

Question 68

The work done on an ideal gas system in an isothermal process is -400 J. What is the change in internal energy?

A)zero
B)-400 J
C)400 J
D)200 J
E)none of the above

Question 69

In an isochoric process, the internal energy of a system decreases by 50 J. What is the heat exchange?

A)zero
B)25 J
C)50 J
D)-50 J
E)none of the above

Question 70

If you add 900 kJ of heat to 900 g of water at 90.0°C, how much water is left in the container? The latent heat of vaporization of water is 22.6 × 10⁵ J/kg.

A)518 g
B)258 g
C)340 g
D)600 g
E)none

Question 71

How much heat needs to be removed from 100 g of 85°C water to make -5°C ice?

A)255 cal
B)168 kcal
C)8.5 kcal
D)16.5 kcal
E)16.8 kcal

Question 72

200 J of work is done in compressing a gas adiabatically. What is the change in internal energy of the gas?

A)zero
B)100 J
C)150 J
D)200 J
E)There is not enough information to determine.

Question 73

How much heat is required to change one gram of 0°C ice to 120°C steam?

A)48.7 cal
B)120 cal
C)540 cal
D)730 cal
E)1505 cal

Question 74

Three moles of an ideal gas with a molar heat capacity at constant volume of 4.9 cal/(mol∙K) and a molar heat capacity at constant pressure of 6.9 cal/(mol∙K) starts at 300 K and is heated at constant pressure to 320 K, then cooled at constant volume to its original temperature. How much heat flows into the gas during this two-step process?

A)710 cal
B)-720 cal
C)0 cal
D)120 cal
E)-120 cal

Question 75

A block of ice at 0°C is added to a 150-g aluminum calorimeter cup that holds 200 g of water at 10°C. If all but 2.00 g of ice melt, what was the original mass of the block of ice?

A)31.1 g
B)35.6 g
C)38.8 g
D)42.0 g
E)47.6 g

Question 76

A quantity of ideal gas requires 800 kJ to raise the temperature of the gas by 10.0 K when the gas is maintained at constant volume. The same quantity of gas requires 900 kJ to raise the temperature of the gas by 10.0 K when the gas is maintained at constant pressure. What is the adiabatic gas constant of this gas?

A)0.889
B)1.13
C)1.22
D)1.67
E)1.40

Question 77

A monatomic gas is cooled by 50 K at constant volume when 831 J of energy is removed from it. How many moles of gas are in the sample?

A)2.50 mol
B)2.15 mol
C)1.50 mol
D)1.33 mol
E)none of the above

Question 78

How much work is done by 3 moles of gas when they triple their volume at a constant temperature of 400 K?

A)12.7 kJ
B)9.97 kJ
C)11.0 kJ
D)15.3 kJ
E)1.20 kJ

Question 79

A certain amount of a monatomic gas is maintained at constant volume as it is cooled by 50 K. This feat is accomplished by removing 400 J of energy from the gas. How much work is done by the gas?

A)zero
B)200 J
C)400 J
D)-400 J
E)none of the above

Question 80

In an isochoric process, the internal energy of a system decreases by 50 J. What is the work done?

A)zero
B)25 J
C)50 J
D)-50 J
E)none of the above