Deck 12: The Laws of Thermodynamics

Question 1

A quantity of monatomic ideal gas expands adiabatically from a volume of 2.0 liters to 6.0 liters.If the initial pressure is P₀, what is the final pressure?

A)9.0 P₀
B)6.2 P₀
C)3.0 P₀
D)0.16 P₀

Answer 1

0.16 P₀

Question 2

During an isobaric process which one of the following does not change?

A)volume
B)temperature
C)internal energy
D)pressure

Answer 2

pressure

Question 3

A 4-mol ideal gas system undergoes an adiabatic process where it expands and does 20 J of work on its environment.What is its change in internal energy?

A)-20 J
B)-5 J
C)zero
D)+20 J

Answer 3

-20 J

Question 4

Area on a P-V diagram has units associated with:

A)energy.
B)momentum.
C)temperature.
D)change in temperature.

Question 5

If an ideal gas does positive work on its surroundings, we may assume, with regard to the gas:

A)temperature increases.
B)volume increases.
C)pressure increases.
D)internal energy decreases.

Question 6

An adiabatic expansion refers to the fact that:

A)no heat is transferred between a system and its surroundings.
B)the pressure remains constant.
C)the temperature remains constant.
D)the volume remains constant.

Question 7

What is the work done on the gas as it expands from pressure P₁ and volume V₁ to pressure P₂ and volume V₂ along the indicated straight line?

A)(P₁ + P₂) (V₁ - V₂)/2
B)(P₁ + P₂) (V₁ - V₂)
C)(P₁ - P₂) (V₁ + V₂)

Question 8

According to the first law of thermodynamics, the sum of the heat gained by a system and the work done on that same system is equivalent to which of the following?

A)entropy change
B)internal energy change
C)temperature change
D)specific heat

Question 9

A 5-mol ideal gas system undergoes an adiabatic free expansion (a rapid expansion into a vacuum), going from an initial volume of 10 L to a final volume of 20 L.How much work is done on the system during this adiabatic free expansion?

A)-50 J
B)-10 J
C)zero
D)+50 J

Question 10

Which of the following increases the internal energy of a solid metal rod?

A)raising it to a greater height
B)throwing it through the air
C)having the rod conduct heat
D)having the rod absorb heat

Question 11

A 2.0-mol ideal gas system is maintained at a constant volume of 4.0 L.If 100 J of heat is added, what is the work done on the system?

A)zero
B)5.0 J
C)-6.7 J
D)20 J

Question 12

A closed 2.0-L container holds 3.0 mol of an ideal gas.If 200 J of heat is added, what is the change in internal energy of the system?

A)zero
B)100 J
C)150 J
D)200 J

Question 13

In an isovolumetric process by an ideal gas, the system's heat gain is equivalent to a change in:

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

Question 14

The adiabatic index of a gas is given by which of the following?

A)C_P /C_V
B)C_V /C_P
C)C_P - C_V
D)C_P + C_V

Question 15

A 4-mol ideal gas system undergoes an adiabatic process where it expands and does 20 J of work on its environment.How much heat is received by the system?

A)-20 J
B)zero
C)+5 J
D)+20 J

Question 16

In an isobaric process 4.5 * 10⁴ J of work is done on a quantity of gas while its volume changes from 2.6 m³ to 1.1 m³.What is the pressure during this process?

A)1.2 * 10⁴ Pa
B)2.4 * 10⁴ Pa
C)3.0 * 10⁴ Pa
D)4.1 * 10⁴ Pa

Question 17

A system is acted on by its surroundings in such a way that it receives 50 J of heat while simultaneously doing 20 J of work.What is its net change in internal energy?

A)70 J
B)30 J
C)zero
D)-30 J

Question 18

The volume of an ideal gas changes from 0.40 to 0.55 m³ although its pressure remains constant at 50 000 Pa.What work is done on the system by its environment?

A)-7 500 J
B)-200 000 J
C)7 500 J
D)200 000 J

Question 19

On a P-V diagram, an ____ process is represented by a horizontal line.

A)isobaric
B)isothermal
C)isovolumetric
D)adiabatic

Question 20

In an isothermal process for an ideal gas system (where the internal energy doesn't change), which of the following choices best corresponds to the value of the work done on the system?

A)its heat intake
B)twice its heat intake
C)the negative of its heat intake
D)twice the negative of its heat intake

Question 21

An electrical generating plant operates at a boiler temperature of 220 $\degree$ C and exhausts the unused heat into a nearby river at 19 $\degree$ C.If the generating plant has a power output of 800 megawatts (MW) and if the actual efficiency is 3/4 the theoretical efficiency, how much heat per second must be delivered to the boiler? (0 $\degree$ C = 273 K)

A)5 200 MW
B)1 810 MW
C)3 620 MW
D)2 620 MW

Question 22

Suppose a power plant uses a Carnot engine to generate electricity, using the atmosphere at 300 K as the low-temperature reservoir.Suppose the power plant produces 1 * 10⁶ J of electricity with the hot reservoir at 500 K during Day One and then produces 1 * 10⁶ J of electricity with the hot reservoir at 600 K during Day Two.The thermal pollution was:

A)greatest on Day One.
B)greatest on Day Two.
C)the same on both days.
D)zero on both days.

Question 23

A cylinder containing an ideal gas has a volume of 2.0 m³ and a pressure of 1.0 * 10⁵ Pa at a temperature of 300 K.The cylinder is placed against a metal block that is maintained at 900 K and the gas expands as the pressure remains constant until the temperature of the gas reaches 900 K.The change in internal energy of the gas is +6.0 * 10⁵ J.How much heat did the gas absorb?

A)0
B)4.0 * 10⁵ J
C)6.0 * 10⁵ J
D)10 * 10⁵ J

Question 24

An ideal gas at pressure, volume, and temperature, P₀, V₀, and T₀, respectively, is heated to point A, allowed to expand to point B also at A's temperature 2T₀, and then returned to the original condition.The internal energy decreases by 3P₀V₀/2 going from point B to point T₀.How much heat left the gas from point B to point T₀?

A)0
B)P₀V₀/2
C)3P₀V₀/2
D)5P₀V₀/2

Question 25

An ideal gas at pressure, volume, and temperature, P₀, V₀, and T₀, respectively, is heated to point A, allowed to expand to point B also at A's temperature 2T₀, and then returned to the original condition.The internal energy decreases by 3P₀V₀/2 going from point B to point T₀.In going around this cycle once, which quantity equals zero?

A)the net change in internal energy of the gas
B)the net work done by the gas
C)the net heat added to the gas
D)All three are zero.

Question 26

If a heat engine has an efficiency of 30% and its power output is 600 W, what is the rate of heat input from the combustion phase?

A)1 800 W
B)2 400 W
C)2 000 W
D)3 000 W

Question 27

During each cycle of operation a refrigerator absorbs 55 cal from the freezer compartment and expels 85 cal to the room.If one cycle occurs every 10 s, how many minutes will it take to freeze 500 g of water, initially at 0 $\degree$ C? (L_v = 80 cal/g)

A)800 min
B)4 400 min
C)120 min
D)60 min

Question 28

A heat engine exhausts 3 000 J of heat while performing 1 500 J of useful work.What is the efficiency of the engine?

A)15%
B)33%
C)50%
D)60%

Question 29

A heat engine receives 6 000 J of heat from its combustion process and loses 4 000 J through the exhaust and friction.What is its efficiency?

A)33%
B)40%
C)67%
D)73%

Question 30

A thermodynamic process that happens very quickly tends to be:

A)isobaric.
B)isothermal.
C)isovolumetric.
D)adiabatic.

Question 31

The maximum theoretical thermodynamic efficiency of a heat engine operating between hot and cold reservoirs is a function of which of the following?

A)hot reservoir temperature only
B)cold reservoir temperature only
C)both hot and cold reservoir temperatures
D)None of the above choices are valid.

Question 32

An electrical generating plant operates at a boiler temperature of 220 $\degree$ C and exhausts the unused heat into a nearby river at 18 $\degree$ C.What is the maximum theoretical efficiency of the plant? (0 $\degree$ C = 273 K)

A)61%
B)32%
C)21%
D)41%

Question 33

A heat engine operating between a pair of hot and cold reservoirs with respective temperatures of 500 K and 200 K will have what maximum efficiency?

A)60%
B)50%
C)40%
D)30%

Question 34

When gasoline is burned, it gives off 46 000 J/g of heat energy.If an automobile uses 13.0 kg of gasoline per hour with an efficiency of 21%, what is the average horsepower output of the engine? (1 hp = 746 W)

A)47 hp
B)110 hp
C)67 hp
D)34 hp

Question 35

According to the second law of thermodynamics, which of the following applies to the heat received from a high temperature reservoir by a heat engine operating in a complete cycle?

A)must be completely converted to work
B)equals the entropy increase
C)converted completely into internal energy
D)cannot be completely converted to work

Question 36

An electrical power plant manages to send 88% of the heat produced in the burning of fossil fuel into the water-to-steam conversion.Of the heat carried by the steam, 40% is converted to the mechanical energy of the spinning turbine.Which of the following choices best describes the overall efficiency of the heat-to-work conversion in the plant (as a percentage)?

A)greater than 88%
B)64%
C)less than 40%
D)40%

Question 37

A turbine takes in 1 000-K steam and exhausts the steam at a temperature of 500 K.What is the maximum theoretical efficiency of this system?

A)24%
B)33%
C)50%
D)67%

Question 38

Heat is applied to an ice-water mixture to melt some of the ice.In this process:

A)work is done by the ice-water mixture.
B)the temperature increases.
C)the internal energy increases.
D)all of the above are correct.

Question 39

In which system is heat usually transferred from the cooler part to the warmer part?

A)a stove as it heats up water
B)a refrigerator that is running
C)an electric fan that is running
D)none of the above, because it is impossible to transfer heat in this manner

Question 40

As the ideal gas expands from pressure P₁ and volume V₁ to pressure P₂ and volume V₂ along the indicated straight line, it is possible that:

A)the temperature stays constant.
B)the internal energy decreases.
C)the gas is changing state.
D)all of the above are impossible for this particular graph.

Question 41

A refrigerator has a coefficient of performance of 4.0.When removing 2.4 * 10⁴ J from inside the refrigerator, how much energy is sent into the environment?

A)9.6 * 10⁴ J
B)3.0 * 10⁴ J
C)1.8 * 10⁴ J
D)0.60 * 10⁴ J

Question 42

A Carnot engine runs between a hot reservoir at T_h and a cold reservoir at T_c.If one of the temperatures is either increased or decreased by 3.5 K, which of the following changes would increase the efficiency by the greatest amount?

A)increasing T_h
B)increasing T_c
C)decreasing T_c
D)cannot be determined from information given

Question 43

If one could observe the individual atoms making up a piece of matter and note that during a process of change their motion somehow became more orderly, then one may assume which of the following in regard to the system?

A)increases in entropy
B)decreases in entropy
C)gains in thermal energy
D)positive work done on

Question 44

According to the first law of thermodynamics, for any process that may occur within an isolated system, which of the following choices applies?

A)entropy remains constant
B)entropy increases
C)entropy decreases
D)None of the above choices apply.

Question 45

The P-V diagram of a cyclic process shows a curve that encloses an area.The work done by the heat engine, represented by the enclosed area, is positive when the path around the area proceeds in which of the following fashions?

A)clockwise
B)counterclockwise
C)It is always positive.
D)It is always negative.

Question 46

A gasoline engine with an efficiency of 30.0% operates between a high temperature T₁ and a low temperature T₂ = 320 K.If this engine operates with Carnot efficiency, what is the high-side temperature T₁?

A)1 070 K
B)868 K
C)614 K
D)457 K

Question 47

On a P-V diagram, if a process involves a closed curve, the area inside the curve represents:

A)internal energy.
B)heat.
C)work.
D)zero.

Question 48

The efficiency of a Carnot engine operating between 100 $\degree$ C and 0 $\degree$ C is most nearly:

A)7%.
B)15%.
C)27%.
D)51%.

Question 49

What is the change in entropy (DS) when one mole of silver (108 g) is completely melted at 961 $\degree$ C? (The heat of fusion of silver is 8.82 * 10⁴ J/kg.)

A)5.53 J/K
B)7.72 J/K
C)9.91 J/K
D)12.10 J/K

Question 50

An avalanche of ice and snow of mass 1 800 kg slides a vertical distance of 160 m down a mountainside.If the temperature of the ice, snow, mountain and surrounding air are all at 0 $\degree$ C, what is the change in entropy of the universe?

A)31 000 J/K
B)10 000 J/K
C)3 200 J/K
D)1 100 J/K

Question 51

An 800-MW electric power plant has an efficiency of 30%.It loses its waste heat in large cooling towers.Approximately how much waste heat (in MJ) is discharged to the atmosphere per second?

A)1 200 MJ
B)1 900 MJ
C)800 MJ
D)560 MJ

Question 52

One kilogram of water at 1.00 atm at the boiling point of 100 $\degree$ C is heated until all the water vaporizes.What is its change in entropy? (For water, L_v = 2.26 * 10⁶ J/kg)

A)12 100 J/K
B)6 060 J/K
C)3 030 J/K
D)1 220 J/K

Question 53

The surface of the Sun is at approximately 5 700 K and the temperature of the Earth's surface is about 290 K.What total entropy change occurs when 1 000 J of heat energy is transferred from the Sun to the Earth?

A)2.89 J/K
B)3.27 J/K
C)3.62 J/K
D)3.97 J/K

Question 54

A 2.00-kg block of ice is at STP (0 $\degree$ C, 1 atm) while it melts completely to water.What is its change in entropy? (For ice, L_f = 3.34 * 10⁵ J/kg)

A)zero
B)584 J/K
C)1 220 J/K
D)2 450 J/K

Question 55

A 1.0-kg chunk of ice at 0 $\degree$ C melts, absorbing 80 000 cal of heat in the process.Which of the following best describes what happens to this system?

A)increased entropy
B)lost entropy
C)entropy maintained constant
D)work converted to energy

Question 56

Of the following heat engines, which has the highest efficiency?

A)Hero's engine
B)a Carnot engine
C)a car's gasoline engine
D)a truck's diesel engine

Question 57

Which of the following choices is an appropriate unit for measuring entropy changes?

A)J*K
B)N*K
C)J/s
D)J/K

Question 58

The Carnot cycle consists of a combination of ____ and ____ processes.

A)isobaric, isovolumetric
B)isovolumetric, adiabatic
C)isobaric, isothermal
D)adiabatic, isothermal

Question 59

A cylinder containing an ideal gas has a volume of 2.0 m³ and a pressure of 1.0 * 10⁵ Pa at a temperature of 300 K.The cylinder is placed against a metal block that is maintained at 900 K and the gas expands as the pressure remains constant until the temperature of the gas reaches 900 K.The change in internal energy of the gas is 6.0 * 10⁵ J.Find the change in entropy of the block associated with the heat transfer to the gas.

A)0
B)+670 J/K
C)-440 J/K
D)-1 100 J/K

Question 60

Which of the following choices best corresponds to what is required by the second law of thermodynamics for any process taking place in an isolated system?

A)entropy decreases
B)entropy remains constant
C)entropy increases
D)entropy equals work done on the system

Question 61

Three Carnot engines operate between temperature reservoirs as follows: Engine A: T_h = 1 300 K, T_c = 1 000 K; Engine B: T_h = 1 000 K, T_c = 700 K; Engine C: T_h = 650 K, T_c = 500 K.Which two engines have the same thermal efficiency?

A)A and B
B)B and C
C)A and C
D)No two have the same thermal efficiency.

Question 62

Entropy is a measure of the ____ of a system.

A)disorder
B)temperature
C)heat
D)internal energy

Question 63

On a PV diagram, 2 curves are plotted, both starting at the same point (P₁, V₁) and both ending at the same increased volume (V₂).One curve is for an isothermal process; the other is for an adiabatic process.Except for the common starting point, which curve is the upper one?

A)The isothermal process curve will always be the upper one.
B)The adiabatic process curve will always be the upper one.
C)Since they start at the same point and end at the same volume, they will coincide.
D)The isothermal one will start out higher, but the adiabatic one will eventually cross it.

Question 64

On a PV diagram, 2 curves are plotted, both starting at the same point and both ending at the same final increased volume.One curve is for an isothermal process; the other is for an adiabatic process.What does the area between these two curves represent?

A)Q absorbed by the isothermal process.
B)W done by the adiabatic process.
C)DU for the isothermal process.
D)Neither Q, W, nor DU for either of the processes is represented.

Question 65

When considering human metabolism in terms of the 1^st Law of Thermodynamics, which of the following represents the metabolic rate?

A)DU / Dt
B)DQ / Dt
C)W / Dt
D)DW / Dt

Question 66

In an isovolumetric process where the pressure increases, are the heat absorbed, work done by the system, and the change in internal energy of the system positive, negative, or zero?

A)Q is +, W is +, and DU is +.
B)Q is +, W is -, and DU is 0.
C)Q is +, W is 0, and DU is +.
D)Q is -, W is 0, and DU is -.

Question 67

A person consumes 2 500 kcal/day while expending 3 500 kcal/day.In a month's time, about how much weight would this person lose if the loss were essentially all from body fat? (Body fat has an energy content of about 4 100 kcal per pound.)

A)1 pound
B)2 pounds
C)7 pounds
D)15 pounds

Question 68

At the dice factory, sets of novelty dice are created where a side with 7 dots replaces the single dot side.The sides then range from 2 to 7 instead of the usually 1 to 6.Using such dice for a game of craps, what will be the most probable roll?

A)7, this change in dots results in the same most probable value.
B)7.5
C)8
D)9

Question 69

A pound of body fat has an energy content of about 4 100 kcal.If a 1 400-kg automobile had an equivalent amount of translational kinetic energy, how fast would it be moving? (0.447 m/s = 1 mph, 1 kcal = 4 186 J)

A)3.1 mph
B)14 mph
C)75 mph
D)350 mph

Question 70

On an average diet, the consumption of 10 liters of oxygen releases how much energy? (4.8 kcal are released per liter of oxygen consumed.)

A)48 kJ
B)200 kJ
C)4.2 kJ
D)4 200 kJ