Gibbs energy was given by Josiah Williard Gibbs, after which the name was given. Gibbs free energy, which is denoted by the symbol G, is equal to the addition of enthalpy and the product of temperature and entropy of the system. ΔG represents the change in Gibbs free energy. If the parameter, i.e., temperature and pressure, are constant, then the Gibbs energy equation can predict the chemical reaction's direction. It tells about the amount of energy that can be used to do work in a chemical reaction.
G=H−TS or ΔG=ΔH-Δ(TS)
Where G represent the Gibbs Energy
H is enthalpy
T is temperature and
S is entropy
Gibbs free energy has the same unit as energy, i.e., joule or kilojoules.
Positive Gibbs energy: - If the Gibbs energy of a reaction is positive, it means the reaction is non-spontaneous. This reaction cannot occur by applying the external force. If the external force is stopped, then the reaction will also stop.
Negative Gibbs energy: - If the Gibbs energy of a reaction is negative, it means the reaction is spontaneous. This reaction can proceed without using any external process. All the natural reactions are spontaneous because it proceeds without external action. If the Gibbs energy is equal to zero, it means the reaction is at equilibrium.
