Entropy is a measure of the degree of randomness of the molecules comprising the system. Higher the disorder, greater is the increase in entropy. Entropy is the function of a quantity of heat which shows the possibility of conversion of that heat into work. The increase in entropy is small when heat is added at a higher temperature and is greater when heat is added at lower temperature. Entropy is an extensive property i.e. it depends on the mass of the system not on the path by which the process take place.
Characteristics of Entropy are as follows:
1. It increases when the heat is supplied irrespective of the fact whether temperature changes or not.
2. Whether temperature changes or not the entropy decreases when heat is rejected.
3. In all the adiabatic processes, the entropy remains constant.
