Gibbs Free Energy
In thermodynamics, the Gibbs free energy is a thermodynamic potential that is defined as the enthalpy of the system minus the product of the temperature times the entropy of the system. Since the enthalpy is defined to be the sum of the internal energy E plus the product of the pressure p and volume V, the Gibbs free energy is defined as:
The change in Gibbs free energy, ΔG, in chemistry, is a very useful parameter. It can be thought of as the maximum amount of work obtainable from a reaction.