Question 1

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

Accepted Answer

The area enclosed by a closed curve on a P-V diagram represents the work done by the system during that process. Therefore, option C is the correct choice as it represents work. Options A and B are incorrect as internal energy and heat are not represented by the area enclosed by a closed curve. Option D is also incorrect as the area does represent a quantity (work).

Question 2

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

Accepted Answer

The Carnot engine has the highest theoretical efficiency of any heat engine, which is given by the Carnot efficiency formula: 
efficiency = (T1-T2)/T1 
where T1 is the temperature of the heat source and T2 is the temperature of the heat sink. The Carnot engine operates on a reversible cycle, which means that it can achieve this maximum efficiency. Hero's engine, car's gasoline engine, and truck's diesel engine are all non-ideal heat engines and operate on irreversible cycles, which limit their efficiency.

Question 3

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

Accepted Answer

Melting of ice leads to an increase in entropy as the solid ice is transformed into a more disordered liquid state. The absorption of heat adds energy to the system and hence more available microstates increase, leading to an increase in entropy.

Question 4

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

Accepted Answer

Entropy changes are measured in units of J/K (joules per kelvin) because entropy is a measure of the amount of energy in a system that is unavailable to do work. Therefore, it is naturally expressed in units of energy per unit of temperature. The other units listed are not appropriate for measuring entropy changes.

Question 5

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?

Accepted Answer

The work done by a heat engine is given by the area enclosed by the PV diagram. If the path around the enclosed area proceeds in a clockwise direction, it means that the work is done in the same direction as the displacement of the system, resulting in a positive value for work. Therefore, option A is the best choice. If the process proceeds counterclockwise, the work done will be negative.

Question 6

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

Accepted Answer

We can use the formula for entropy change during a phase transition:

ΔS = L/T

where L is the latent heat of vaporization and T is the boiling point temperature.

Using the given value for latent heat of vaporization and temperature, we get:

ΔS = (2.26 × 10^6 J/kg) / 373 K

ΔS = 6,057 J/K

However, this value is for 1 kg of water, and the problem asks for the entropy change for 1.2 kg. So we need to multiply by 1.2:

ΔS = 6,057 J/K * 1.2

ΔS = 7,268.4 J/K

which is closest to answer choice B: 7,271 J/K.

Question 7

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?

Accepted Answer

An increase in orderliness suggests a decrease in entropy, as entropy is a measure of disorder or randomness.

Question 8

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 980 J of heat energy is transferred from the Sun to the Earth?
​

Accepted Answer

The answer of The surface of the Sun is at...

Question 9

The efficiency of a Carnot engine operating between 95°C and 0°C is most nearly:
​

Accepted Answer

The efficiency of a Carnot engine is given by the formula: efficiency = 1 - Tc/Th, where Tc is the temperature of the cold reservoir and Th is the temperature of the hot reservoir. Plugging in values, we get efficiency = 1 - (273+0)/(273+95) = 26%. Therefore, the answer is (C).

Question 10

A cylinder containing an ideal gas has a volume of 2 m³ and a pressure of 1.6 × 10⁵ Pa at a temperature of 320 K.The cylinder is placed against a metal block that is maintained at 840 K and the gas expands as the pressure remains constant until the temperature of the gas reaches 840 K.The change in internal energy of the gas is 6.7 × 10⁵ J.Find the change in entropy of the block associated with the heat transfer to the gas.

Accepted Answer

The answer of A cylinder containing an ideal gas has...

Question 11

A refrigerator has a coefficient of performance of 4.When removing 2.3 × 10⁴ J from inside the refrigerator,how much energy is sent into the environment?

Accepted Answer

The answer of A refrigerator has a coefficient of performance...

Question 12

An 870-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?
​

Accepted Answer

The answer of An 870-MW electric power plant has an...

Question 13

A gasoline engine with an efficiency of 33.8% operates between a high temperature T₁ and a low temperature T₂ = 370 K.If this engine operates with Carnot efficiency,what is the high-side temperature T₁?

Accepted Answer

The answer of A gasoline engine with an efficiency of...

Question 14

A 2.05-kg block of ice is at STP (0°C,1 atm)while it melts completely to water.What is its change in entropy? (For ice,L_f = 3.34 × 10⁵ J/kg)

Accepted Answer

The answer of A 2.05-kg block of ice is at...

Question 15

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

Accepted Answer

The Carnot cycle consists of two adiabatic processes (no heat transfer) and two isothermal processes (constant temperature).

Question 16

An avalanche of ice and snow of mass 2,000 kg slides a vertical distance of 180 m down a mountainside.If the temperature of the ice,snow,mountain and surrounding air are all at 0°C,what is the change in entropy of the universe?
​

Accepted Answer

To calculate the change in entropy of the universe, we need to use the formula: ΔS_univ = ΔS_system + ΔS_surroundings. Here, the system is the avalanche of ice and snow, and the surroundings are the mountain and the air around it.

We know that the temperature of the system and the surroundings are the same, so ΔS_system = Q/T, where Q is the heat transferred and T is the temperature. Since there is no change in temperature, ΔS_system = 0.

The only change in entropy comes from the surroundings, which experience an increase in entropy as the avalanche moves down the mountain. We can calculate this using the formula: ΔS_surroundings = Q/T. Here, Q is the heat transferred from the avalanche to the surroundings, and we can calculate it using the formula for potential energy: Q = mgh, where m is the mass of the avalanche, g is the acceleration due to gravity, and h is the height through which the avalanche falls.

Therefore, Q = (2000 kg)(9.8 m/s^2)(180 m) = 3,528,000 J.

Since the temperature is 0°C = 273 K, ΔS_surroundings = Q/T = 3,528,000 J / 273 K = 12,923 J/K.

Therefore, the answer is B.

Question 17

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?

Accepted Answer

According to Carnot's theorem, the maximum efficiency of a heat engine depends only on the temperature difference between the hot and cold reservoirs. Therefore, changing the temperature of the hot reservoir or the cold reservoir by the same amount will result in the same change in efficiency. However, decreasing the temperature of the cold reservoir will have a greater impact on efficiency since it will increase the temperature difference between the reservoirs, resulting in a larger increase in efficiency compared to increasing the temperature of the hot reservoir.

Question 18

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?

Accepted Answer

The second law of thermodynamics states that in any isolated system, the total entropy (disorder) will always increase. Therefore, the only choice that corresponds to this requirement is C) entropy increases. Choices A and B are incorrect because they imply a decrease or no change in entropy, which is not in accordance with the second law of thermodynamics. Choice D is incorrect because entropy and work done are two different concepts that cannot be equated.

Question 19

What is the change in entropy (ΔS)when one mole of silver (102 g)is completely melted at 962°C? (The heat of fusion of silver is 8.82 × 10⁴ J/kg. )

Accepted Answer

The answer of What is the change in entropy (ΔS)when...

Question 20

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

Accepted Answer

The first law of thermodynamics, also known as the law of conservation of energy, states that energy cannot be created or destroyed, only transferred or converted from one form to another. It does not specify any changes in entropy during processes within an isolated system, which is a separate concept governed by the second law of thermodynamics. Therefore, none of the choices apply.

Quiz 12: The Laws of Thermodynamics Work in Thermodynamic Processes

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

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

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

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

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?

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

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?

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 980 J of heat energy is transferred from the Sun to the Earth?

The efficiency of a Carnot engine operating between 95°C and 0°C is most nearly:

A refrigerator has a coefficient of performance of 4.When removing 2.3 × 10⁴ J from inside the refrigerator,how much energy is sent into the environment?

An 870-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 gasoline engine with an efficiency of 33.8% operates between a high temperature T₁ and a low temperature T₂ = 370 K.If this engine operates with Carnot efficiency,what is the high-side temperature T₁?

A 2.05-kg block of ice is at STP (0°C,1 atm) while it melts completely to water.What is its change in entropy? (For ice,L_f = 3.34 × 10⁵ J/kg)

The Carnot cycle consists of a combination of and processes.

An avalanche of ice and snow of mass 2,000 kg slides a vertical distance of 180 m down a mountainside.If the temperature of the ice,snow,mountain and surrounding air are all at 0°C,what is the change in entropy of the universe?

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?

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?

What is the change in entropy (ΔS) when one mole of silver (102 g) is completely melted at 962°C? (The heat of fusion of silver is 8.82 × 10⁴ J/kg. )

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

Quiz 12: The Laws of Thermodynamics Work in Thermodynamic Processes

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

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

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

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

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?

1.2 kilogram of water at 1.00 atm at the boiling point of 100°C is heated until all the water vaporizes.What is its change in entropy? (For water,Lv = 2.26 × 106 J/kg) ​

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?

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 980 J of heat energy is transferred from the Sun to the Earth? ​

The efficiency of a Carnot engine operating between 95°C and 0°C is most nearly: ​

A refrigerator has a coefficient of performance of 4.When removing 2.3 × 104 J from inside the refrigerator,how much energy is sent into the environment? ​

An 870-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 gasoline engine with an efficiency of 33.8% operates between a high temperature T1 and a low temperature T2 = 370 K.If this engine operates with Carnot efficiency,what is the high-side temperature T1? ​

A 2.05-kg block of ice is at STP (0°C,1 atm) while it melts completely to water.What is its change in entropy? (For ice,Lf = 3.34 × 105 J/kg) ​

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

An avalanche of ice and snow of mass 2,000 kg slides a vertical distance of 180 m down a mountainside.If the temperature of the ice,snow,mountain and surrounding air are all at 0°C,what is the change in entropy of the universe? ​

A Carnot engine runs between a hot reservoir at Th and a cold reservoir at Tc.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?

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?

What is the change in entropy (ΔS) when one mole of silver (102 g) is completely melted at 962°C? (The heat of fusion of silver is 8.82 × 104 J/kg. ) ​

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

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

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 980 J of heat energy is transferred from the Sun to the Earth?

The efficiency of a Carnot engine operating between 95°C and 0°C is most nearly:

A refrigerator has a coefficient of performance of 4.When removing 2.3 × 10⁴ J from inside the refrigerator,how much energy is sent into the environment?

An 870-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 gasoline engine with an efficiency of 33.8% operates between a high temperature T₁ and a low temperature T₂ = 370 K.If this engine operates with Carnot efficiency,what is the high-side temperature T₁?

A 2.05-kg block of ice is at STP (0°C,1 atm) while it melts completely to water.What is its change in entropy? (For ice,L_f = 3.34 × 10⁵ J/kg)

The Carnot cycle consists of a combination of and processes.

An avalanche of ice and snow of mass 2,000 kg slides a vertical distance of 180 m down a mountainside.If the temperature of the ice,snow,mountain and surrounding air are all at 0°C,what is the change in entropy of the universe?

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?

What is the change in entropy (ΔS) when one mole of silver (102 g) is completely melted at 962°C? (The heat of fusion of silver is 8.82 × 10⁴ J/kg. )