Question

In a refrigerator, heat is transferred from a lowertemperature medium (the refrigerated space) to a highertemperature one (the kitchen air). Is this a violation of the second law of thermodynamics? Explain.

Short answer

Answer: No, the heat transfer process in a refrigerator from a low-temperature medium to a high-temperature one does not violate the second law of thermodynamics. This is because the refrigerator consumes external work to accomplish the heat transfer, which results in an increase in the total entropy of the system.

Step-by-step solution

Recall the Second Law of Thermodynamics

The second law of thermodynamics states that the total entropy of an isolated system can never decrease over time, and is constant if and only if all processes are reversible. In terms of heat transfer, it implies that heat cannot spontaneously flow from a colder body to a warmer body without any external work.

Understand the refrigerator's working principle

A refrigerator works on the principle of a heat pump, which uses external work to transfer heat from a low-temperature medium (refrigerated space) to a high-temperature medium (kitchen air). The refrigerator carries out this process through a cyclic process, consisting of compression, condensation, expansion, and evaporation of a refrigerant.

Determine if the refrigerator operation violates the second law

The refrigerator transfers heat from a lower-temperature medium to a higher-temperature one, but it does so by using external work. As a result, the total entropy of the system (refrigerator, refrigerated space, and the kitchen) increases. Therefore, the refrigerator's operation does not violate the second law of thermodynamics, as the overall entropy of the system increases during the process.

Conclusion

The process of transferring heat from a low-temperature medium to a high-temperature medium in a refrigerator does not violate the second law of thermodynamics. This is because the refrigerator consumes external work to accomplish the heat transfer, which results in an increase in the total entropy of the system.