Exam 22: Heat Engines, Entropy, and the Second Law of Thermodynamics

A refrigerator has a coefficient of performance of 4. If the refrigerator absorbs 30 cal of heat from the cold reservoir in each cycle, the heat expelled (in cal) into the heat reservoir is

Which answer below is not a statement of the second law of thermodynamics?

A gasoline engine absorbs 2 500 J of heat and performs 1 000 J of mechanical work in each cycle. The amount of heat expelled in each cycle is

Find the change in entropy (in J/K) when 5.00 moles of an ideal monatomic gas are allowed to expand isobarically from an initial volume of 20 cm³ to a final volume of 100 cm³.

A lawn mower has a 6-horsepower engine (1 HP = 750 W). If the engine has an efficiency of 20%, and the throttle is such that the engine cycles 10 times a second, the heat that is expelled in one cycle is

For the same temperature increase in a system, the change in entropy, ΔS, is largest in a reversible

When water of mass m and specific heat c is heated from absolute temperature T₁ to absolute temperature T₂, its change in entropy is

Ten kilograms of water at 0°C is mixed with 10 kg of water at 100°C. The change in entropy (in cal/K) of the system is

Exactly 500 grams of ice are melted at a temperature of 32°F. (L_ice = 333 J/g.) The change in entropy (in J/K) is

Suppose there are 3 molecules in a container. If each molecule has a 1-in-2 chance of being in the left half of the container, what is the probability that there are exactly 2 molecules in the left half of the container?

Selena states that proves that entropy has a definite value at the beginning and end of an adiabatic free expansion. Ron says , where W is the number of microstates of a given macrostate. Which one, if either, is correct?

An ideal gas is allowed to expand adiabatically. Assume the process is reversible. The change in entropy is

The change in entropy when 1 kg of ice melts at 0°C is (in J/K). (L_ice = 333 J/g.)

In an engine operating in the Otto cycle, the final volume of the fuel-air mixture is one sixth the initial volume. Assume γ = 1.4. The maximum theoretical efficiency of this cycle, in per cent, is

Which of the following is an almost reversible process?

Since L_ice = 333 J/g, the change in entropy (in cal/K) when 1.00 kg of ice melts is

A vessel containing 5.0 kg of water at 10°C is put into a refrigerator. The 1/7 HP motor (1 HP = 746 W) runs for 5.0 minutes to cool the liquid to the refrigerator's low temperature, 0°C. What is the κ of the refrigerator?

If n moles of an ideal gas are compressed isothermally from an initial volume V₁ to a final volume V₂, the change in entropy is

A heat pump has a coefficient of performance of 4. If the heat pump absorbs 20 cal of heat from the cold outdoors in each cycle, the heat expelled (in cal) to the warm indoors is

A violation of the second law of thermodynamics would occur if