Laws of Thermodynamics: A Brief Explanation [Definition]

Laws of thermodynamics

Like every other science, thermodynamics is also governed by certain laws.

There are basically four laws which are base of thermodynamics. These laws are

1. Zeroth law of thermodynamics
2. First law of thermodynamics
3. Second law of thermodynamics
4. Third law of thermodynamics

Now let us discuss each of them one by one.

Zeroth law of thermodynamics

Zeroth law of thermodynamics states that if two bodies are in thermal equilibrium with a third body then they must be in thermal equilibrium with each other.

Zeroth law of thermodynamics is the base of principle of temperature measurement of a body.

First law of thermodynamics

First law of thermodynamics is all about conservation of energy, it states that “Energy can neither be created nor be destroyed, it can only change its forms”.

Second law of thermodynamics

There are two statements associated with the second law of thermodynamics. They are

1. Kelvin-Planck statement of the second law
2. Clausius statement of the second law

Kelvin-Planck statement of the second law

No process is possible whose sole result is the absorption of heat from a reservoir and the conversion of this heat into work.

Clausius statement of the second law

No process is possible whose sole result is the transfer of heat from a cooler to a hotter body.

Third law of thermodynamics

The Third Law of Thermodynamics states that as the temperature of a system approaches absolute zero, its entropy approaches a constant (for pure perfect crystals, this constant is zero).

Also read:

What is a thermodynamic system?

What is two property rule in thermodynamics?

What is dead state of a thermodynamic system?

What is a point function?

What are different types of pressures?

References:

Second law definition: https://web.mit.edu/16.unified/www/FALL/thermodynamics/notes/node37.html

Third law of thermodynamics: https://www.allaboutscience.org/third-law-of-thermodynamics-faq.htm

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