Second Law of Thermodynamics and its Limitations

Second Law of Thermodynamics

Second law of thermodynamics is a fundamental principle describes the behavior of energy in thermodynamic systems, particularly concerning heat transfer and the concept of entropy. Second law of thermodynamics can be explained by the following statements which was given by various scientist-

1. Kelvin and Plank's Statement

It is impossible to construct a heat engine(H.E.) that operates in a cyclic process and converts all the heat absorbed from a heat reservoir into work without transferring heat to a colder reservoir.
Q₁ ≠ W_net

2. R Clausious Statement

Heat can not be itself passes from a colder body to hotter body without expenditure of external energy.
The energy of the universe remains constant but the entropy of the universe approaches maximum in reversible process.

3. All the natural and spontaneous process takes place only in one direction but can not be reverse.

4. For any process, the change in entropy of the system plus change in entropy of the surrounding is zero.
ΔS_system + ΔS_surrounding = 0

5. The gasses diffuses from the region of higher pressure to the region of lower pressure until the pressure becomes uniform.

Limitations of Second Law of Thermodynamics

Second law of thermodynamics has also some limitations which are given below-

1. Second law of thermodynamics applies to closed systems only but practically not impossible to create a truly closed system in nature.
2. It deals with the irreversibility of heat conversion to another form only.
3. The efficiency of a heat engine can never be 100 per cent.
4. Second law of thermodynamics doesn't predict what will happen under certain conditions.

First Law of Thermodynamics and Its Limitations
Third Law of Thermodynamics and Its Limitations

Second Law of Thermodynamics MCQs