Explain and define the 3 laws …

Zeroth Law of Thermodynamics

• Zeroth law of thermodynamics states that when two systems are in thermal equilibrium through a third system separately then they are in thermal equilibrium with each other also.
  • Foreg: - Consider two systems A and B which are separated by an adiabatic wall. Heat flow happens between systems A and C, and between B and C, due to which all 3 systems attain thermal equilibrium.

First Law of Thermodynamics

• The First law of thermodynamics is same as law of conservation of energy.
• According to law of energy conservation: - Energy can neither be created nor be destroyed, only transformed to other forms.
• According to first law of thermodynamics:- The change in the internal energy of a closed system is equal to the amount of heat supplied to the system, minus the amount of work done by the system on its surroundings.
• Examples:- Consider a ball falling from the roof of the building when at top of the building the ball has only potential energy and when it starts falling potential energy decreases and kinetic energy starts increasing. At the ground it has only kinetic energy.

Second law of Thermodynamics

There are 2 statements of second law of thermodynamics given by two scientists:

• Kelvin-Planck ∫Statement: - No process is possible whose result is the absorption of heat from a reservoir and the complete conversion of the heat into work.
• Clausius statement: - No process is possible whose result is the transfer of heat from a colder object to a hotter object.

Explanation of Kelvin-Planck Statement: It is always impossible that the total amount of heat which is supplied to system will get converted to work, and there will always be loss of heat. Complete conversion of heat into work is not possible.

Explanation of Clausius statement: - Transfer of heat from colder body to hotter body won’t take place until some external work is done on the system.