Question

State the Three Laws of Thermodynamics (2nd Law has multiple parts).

Answer 1

Zeroth law:

If two systems are simultaneously in thermal equilibrium with third system, then the two systems are also in thermal equilibrium.

If A and B are two systems in thermal equilibrium with third system C separately, then A and B are also in thermal equilibrium.

First law:

Amount if heat energy given to a system ∆Q is useful to do external work W and to increase internal energy of system ∆U

Mathematically, ∆Q = ∆U+W

This law is derived from conservation of energy.

∆U positivee if heat energy given to system

∆U negative if heat energy released by system.

∆U positive if temperature of system increased.

∆U negative if temperature of system decreased

W is positive if work is done by system

W is negative if work is done in system.

SECOND LAW: There are different statements for second law, two important statements were done by Claysis and Kelvin.

Clausis : It is impossible to transfer heat energy from cold body to hot body without a the aid of an external agent.

Krlvin: It is impossible to cool the cold to coolest of its surroundings without the aid of external agent.

These to laws are equivalent laws and stated from the conclusion taken from Carnot reversible heat engine.