When an object cools down, heat is withdrawn from it. Does the entropy of the object decrease in this process? If yes, is it a violation of the second law of thermodynamics state in terms of increase in entropy?

Question

Philoid · Accepted Answer

1. The entropy of the system is the measure of molecular disorder or randomness, of a system.

2. When heat is withdrawn from the system, temperature decreases. This means that there is less randomness in the system. So, entropy will decrease.

3. But the heat withdrawn from the system is supplied to surroundings. Therefore, the entropy of the surroundings will increase.

4. The second law of thermodynamics states that net entropy of the universe always increases.

5. So, if the entropy of the system decreases, the entropy of the surroundings increases. Therefore, there is always a net increase in entropy.

6. Hence second law of thermodynamic is not violated in this case.