What is the difference between first and second laws of thermodynamics?

1 Answer
Oct 30, 2015


I will explain the laws of thermodynamics in the simplest way possible.


There are four laws in Thermodynamics namely, the zeroth law, 1st law, 2nd law and 3rd law.

#color (red) ("zeroth law")#:

This states that if system A is in thermal equilibrium (no observable change) with system C and system B is also in thermal equilibrium with system C then system A must be in thermal equilibrium with system C.

Or mathematically, if A = C and B = C then A = B.

#color (red) ("1st law")#:

Also known as the law of conservation of energy. This law states that energy cannot be created nor destroyed. In other words, the total amount of energy coming in the system must be equal to the total energy coming out of the system. The energy might be transferred and transformed but it must remain constant.

#color (red) ("2nd law")#:

states that in the natural flow of things, the system always favors chaos rather than order. In other words, the entropy (amount of disorder) in a given closed system irreversibly increases and the total amount of entropy is the sum of entropies between the system and its surroundings.

#color (red) ("3rd law")#:

states that the entropy of a perfect crystal system at absolute temperature (0 Kelvin) must be equal to zero. This law states the impossibility of a perfect system as even crystals (which has the most rigid and ordered structure) has to be perfect and in absolute zero temperature to have a zero entropy.

Hope these helps.