Free Energy

Reactions occur in different environments and under different conditions. In order to describe the spontaneity of reactions, J. Willard Gibbs derived the Gibbs free energy equation. This equation related the enthalpy of a reaction to its entropy at a certain temperature. Once you have solved for free energy (ΔG), the value of (ΔG) describes if a reaction is spontaneous, non-spontaneous, or at equilibrium. A spontaneous reaction occurs without any outside energy or catalysts, while a non-spontaneous reaction will not occur without additional energy.