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?

Question

Quizplus · 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.

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