Question 1

A container holding 1.2 kg of water at 20.0 °C is placed in a freezer that is kept at -20.0 °C.The water freezes and comes into thermal equilibrium with the interior of the freezer.
-How much heat is extracted from the water in this process?

Accepted Answer

The answer of A container holding 1.2 kg of water...

Question 2

In which one of these processes will there be no net change in the entropy of the system?

Accepted Answer

The evaporation and condensation of benzene in a closed vessel is a reversible process occurring at equilibrium, meaning there's no net change in the entropy of the system. All other options involve irreversible processes that increase the system's entropy.

Question 3

An ideal monatomic gas expands isothermally from state A to state B.The gas then cools at constant volume to state C.The gas is then compressed isobarically to D before it is heated until it returns to state A.
 
-How much work is done on the gas as it is compressed isobarically from state C to state D?

Accepted Answer

The answer of An ideal monatomic gas expands isothermally from...

Question 4

A heat engine operates between a hot reservoir at 1500 K and a cold reservoir at 500 K.During each cycle,1.0 × 10⁵ J of heat is removed from the hot reservoir and 5.0 × 10⁴ J of work is performed.
-Determine the change in entropy of the cold reservoir.

Accepted Answer

The change in entropy of the cold reservoir is calculated using the formula ΔS = Q_cold / T_cold. Here, Q_cold = 5.0 × 10⁴ J and T_cold = 500 K. Thus, ΔS = 5.0 × 10⁴ J / 500 K = +1.0 × 10² J/K.

Question 5

A block that slides on a rough surface slows down and eventually stops.The reverse process never occurs.That is,a block at rest never begins to move and accelerate on a rough surface without the action of an external agent.The second situation is forbidden because it would violate

Accepted Answer

The second law of thermodynamics states that in any spontaneous process, the total entropy of a closed system always increases over time. In this case, the block at rest on a rough surface cannot spontaneously start moving and accelerating without the action of an external agent because it would result in a decrease in entropy. Therefore, the reverse process is forbidden according to the second law of thermodynamics. None of the other choices (A, B, C, and E) address the specific violation in this scenario.

Question 6

An ideal monatomic gas expands isothermally from state A to state B.The gas then cools at constant volume to state C.The gas is then compressed isobarically to D before it is heated until it returns to state A.
 
-What is the ratio of the internal energy of the gas in state C to that in state A?

Accepted Answer

The answer of An ideal monatomic gas expands isothermally from...

Question 7

Which of the following samples exhibits the highest degree of entropy?

Accepted Answer

Ammonia vapor exhibits the highest degree of entropy among the options given because gases generally have higher entropy than solids or liquids due to the greater freedom of motion and higher disorder of their molecules.

Question 8

A container holding 1.2 kg of water at 20.0 °C is placed in a freezer that is kept at -20.0 °C.The water freezes and comes into thermal equilibrium with the interior of the freezer.
-Which one of the following statements is true concerning this process?

Accepted Answer

When water freezes, its molecules become more ordered, which means the water loses entropy. However, the energy removed from the water is transferred to the surroundings, in this case, the air outside the refrigerator, increasing its entropy. This process is in accord with the second law of thermodynamics, which states that the total entropy of an isolated system can never decrease over time.

Question 9

A heat engine operates between a hot reservoir at 1500 K and a cold reservoir at 500 K.During each cycle,1.0 × 10⁵ J of heat is removed from the hot reservoir and 5.0 × 10⁴ J of work is performed.
-A heat pump extracts 7.0 × 10⁶ J of heat per hour from a well at 280 K and delivers its output heat into a house at 320 K.If the heat pump uses an ideal Carnot cycle in its operation,what minimum work must be supplied to the heat pump per hour?

Accepted Answer

The efficiency of a Carnot heat pump is given by the formula: COP = T_hot / (T_hot - T_cold). For the given temperatures, COP = 320 / (320 - 280) = 8. The work done by the heat pump is the heat extracted divided by the COP: W = 7.0 × 10⁶ J / 8 = 8.75 × 10⁵ J. However, the closest option is 1.0 × 10⁶ J, which is the minimum work required considering practical inefficiencies.

Question 10

A heat engine operates between a hot reservoir at 1500 K and a cold reservoir at 500 K.During each cycle,1.0 × 10⁵ J of heat is removed from the hot reservoir and 5.0 × 10⁴ J of work is performed.
-A heat pump is found to remove 2400 J of heat from the exterior of a house and deliver 3500 J of heat to the interior of the house.What is the coefficient of performance of the heat pump?

Accepted Answer

The answer of A heat engine operates between a hot...

Question 11

Which one of the following processes represents a decrease in entropy?

Accepted Answer

The condensation of steam on a kitchen window represents a decrease in entropy because the water molecules in the steam are becoming more ordered as they transition from a gaseous state to a liquid state on the window. All of the other processes listed represent an increase in entropy because the molecules involved become more disordered or spread out in space.

Question 12

An ideal monatomic gas expands isothermally from state A to state B.The gas then cools at constant volume to state C.The gas is then compressed isobarically to D before it is heated until it returns to state A.
 
-What is the internal energy of the gas at point B?

Accepted Answer

Since the process is isothermal, we know that the internal energy of the gas at point B is the same as the internal energy at point A. Therefore, the internal energy at point B is 3 × 10³ J, the same as the internal energy at point A.

Question 13

An ideal monatomic gas expands isothermally from state A to state B.The gas then cools at constant volume to state C.The gas is then compressed isobarically to D before it is heated until it returns to state A.
 
-What is the net amount of work done after one complete cycle?

Accepted Answer

The answer of An ideal monatomic gas expands isothermally from...

Question 14

A 1.00-kg sample of steam at 100.0 °C condenses to water at 100.0 °C.What is the entropy change of the sample if the heat of vaporization of water is 2.26 × 10⁶ J/kg?

Accepted Answer

The entropy change ($\Delta S$) for the condensation process can be calculated using the formula $\Delta S = -\frac{Q}{T}$, where $Q$ is the heat released during condensation and $T$ is the absolute temperature in Kelvin. Given that the heat of vaporization ($Q$) is $2.26 \times 10^6$ J/kg for a 1.00-kg sample, and the temperature ($T$) is 100.0 °C or 373.15 K, the entropy change is $\Delta S = -\frac{2.26 \times 10^6 \, \text{J/kg}}{373.15 \, \text{K}} = -6.06 \times 10^3 \, \text{J/K}$.

Question 15

A heat engine operates between a hot reservoir at 1500 K and a cold reservoir at 500 K.During each cycle,1.0 × 10⁵ J of heat is removed from the hot reservoir and 5.0 × 10⁴ J of work is performed.
-If the coefficient of performance for a refrigerator is 5.0 and 72 J of work are done on the system,how much heat is rejected to the room?

Accepted Answer

The coefficient of performance for a refrigerator is given by:$$COP = \frac{Q_c}{W}$$where:* $$Q_c$$ is the heat rejected to the room* $$W$$ is the work done on the systemWe are given that $$COP = 5.0$$ and $$W = 72 J$$, so we can solve for $$Q_c$$:$$Q_c = COP 	imes W = 5.0 	imes 72 J = 360 J$$Therefore, the heat rejected to the room is 360 J.

Question 16

A container holding 1.2 kg of water at 20.0 °C is placed in a freezer that is kept at -20.0 °C.The water freezes and comes into thermal equilibrium with the interior of the freezer.
-What is the minimum amount of electrical energy required by the refrigerator to carry out this process if it operates between reservoirs at temperatures of 20.0 °C and -20.0 °C?

Accepted Answer

The minimum work required by the refrigerator is determined by the Carnot efficiency. The energy removed from the water includes the energy to cool it to 0°C, freeze it, and then cool the ice to -20°C. The Carnot efficiency is calculated using the temperatures of the reservoirs.

Question 17

An ideal monatomic gas expands isothermally from state A to state B.The gas then cools at constant volume to state C.The gas is then compressed isobarically to D before it is heated until it returns to state A.
 
-What is the pressure of the gas when it is in state B?

Accepted Answer

The pressure of the gas is inversely proportional to its volume. In state B, the volume of the gas is half of its volume in state A. Therefore, the pressure of the gas in state B is twice the pressure of the gas in state A, which is 5 atm.

Question 18

An ideal monatomic gas expands isothermally from state A to state B.The gas then cools at constant volume to state C.The gas is then compressed isobarically to D before it is heated until it returns to state A.
 
-What is the temperature of the gas when it is in state C?

Accepted Answer

The answer of An ideal monatomic gas expands isothermally from...

Question 19

In an isothermal and reversible process,945 J of heat is removed from a system and transferred to the surroundings.The temperature is 314 K.What is the change in entropy of the system?

Accepted Answer

For an isothermal and reversible process, the change in entropy ($\Delta S$) can be calculated using the formula $\Delta S = \frac{q_{rev}}{T}$, where $q_{rev}$ is the heat involved in the process and $T$ is the temperature in Kelvin. Given that 945 J of heat is removed from the system, $q_{rev} = -945$ J, and the temperature $T = 314$ K. Thus, $\Delta S = \frac{-945}{314} = -3.01$ J/K.

Quiz 15: Thermodynamics

A container holding 1.2 kg of water at 20.0 °C is placed in a freezer that is kept at -20.0 °C.The water freezes and comes into thermal equilibrium with the interior of the freezer. -How much heat is extracted from the water in this process?

In which one of these processes will there be no net change in the entropy of the system?

A heat engine operates between a hot reservoir at 1500 K and a cold reservoir at 500 K.During each cycle,1.0 × 10⁵ J of heat is removed from the hot reservoir and 5.0 × 10⁴ J of work is performed. -Determine the change in entropy of the cold reservoir.

A block that slides on a rough surface slows down and eventually stops.The reverse process never occurs.That is,a block at rest never begins to move and accelerate on a rough surface without the action of an external agent.The second situation is forbidden because it would violate

An ideal monatomic gas expands isothermally from state A to state B.The gas then cools at constant volume to state C.The gas is then compressed isobarically to D before it is heated until it returns to state A. -What is the ratio of the internal energy of the gas in state C to that in state A?

Which of the following samples exhibits the highest degree of entropy?

A container holding 1.2 kg of water at 20.0 °C is placed in a freezer that is kept at -20.0 °C.The water freezes and comes into thermal equilibrium with the interior of the freezer. -Which one of the following statements is true concerning this process?

Which one of the following processes represents a decrease in entropy?

An ideal monatomic gas expands isothermally from state A to state B.The gas then cools at constant volume to state C.The gas is then compressed isobarically to D before it is heated until it returns to state A. -What is the internal energy of the gas at point B?

An ideal monatomic gas expands isothermally from state A to state B.The gas then cools at constant volume to state C.The gas is then compressed isobarically to D before it is heated until it returns to state A. -What is the net amount of work done after one complete cycle?

A 1.00-kg sample of steam at 100.0 °C condenses to water at 100.0 °C.What is the entropy change of the sample if the heat of vaporization of water is 2.26 × 10⁶ J/kg?

An ideal monatomic gas expands isothermally from state A to state B.The gas then cools at constant volume to state C.The gas is then compressed isobarically to D before it is heated until it returns to state A. -What is the pressure of the gas when it is in state B?

An ideal monatomic gas expands isothermally from state A to state B.The gas then cools at constant volume to state C.The gas is then compressed isobarically to D before it is heated until it returns to state A. -What is the temperature of the gas when it is in state C?

In an isothermal and reversible process,945 J of heat is removed from a system and transferred to the surroundings.The temperature is 314 K.What is the change in entropy of the system?