Gibbs free energy at equilibrium refers to the amount of energy that is available to do work in a system when it is at equilibrium, or in a state of balance. It is a measure of the thermodynamic potential of a system and is denoted by the symbol G.
Gibbs free energy is directly related to equilibrium through the equation ΔG = ΔH - TΔS, where ΔG is change in Gibbs free energy, ΔH is change in enthalpy, T is temperature, and ΔS is change in entropy. At equilibrium, ΔG is equal to zero, indicating that the system is in a state of balance and no further changes will occur.
The change in Gibbs free energy at equilibrium is affected by changes in enthalpy, entropy, and temperature. An increase in enthalpy or a decrease in entropy will result in a positive change in Gibbs free energy, indicating that the reaction is not favorable. On the other hand, a decrease in enthalpy or an increase in entropy will result in a negative change in Gibbs free energy, indicating that the reaction is favorable.
The change in Gibbs free energy at equilibrium can be calculated using the equation ΔG = -RTlnK, where R is the gas constant, T is the temperature in Kelvin, and K is the equilibrium constant. This equation is known as the Gibbs free energy equation and is used to calculate the change in Gibbs free energy for a given reaction at a specific temperature.
A negative change in Gibbs free energy at equilibrium indicates that the reaction is thermodynamically favorable. This means that the reaction will proceed in the forward direction and the products will be favored over the reactants. Additionally, a negative change in Gibbs free energy at equilibrium can also indicate that the reaction is exergonic, meaning that it releases energy in the form of heat or work.