The driving force to bring a process to equilibrium is given by R T ln Q. Q is the quotient or ratio of product concentrations divided by the reactant concentrations, each raised to a power equal to the stoichiometric coefficient of the product or reactant in the balanced chemical equation. Thus, at conditions other than equilibrium, DG = DG° + R T ln Q. At equilibrium, DG = 0, so DG° = -R T ln K (where K is the equilibrium constant).