What is free energy??

THermodynamic free enrgy is the amount of work a thermodynamic system can perform. 

The concept is useful in the thermodynamics of chemical or thermal processes in engineering and science. The free energy is the internal energy of a system minus the amount of energy that cannot be used to perform work. This unusable energy is given by the entropy of a system multiplied by the temperature of the system.

Like the internal energy, the free energy is a thermodynamic state function.

Approved

free energy is a concept in thermodynamics.

it is represented by G.

G=H-TS

where H=Enthalpy

T=temperature

S=entropy