Free-energy relationship
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In chemical kinetics, a free-energy relationship or linear Gibbs energy relation relates the common logarithm of a reaction rate constant, which is proportional to the activation energy, for one series of reactions with the logarithm of the equilibrium constant, which is proportional to the Gibbs free energy, for a related series of reactions. Establishing free-energy relationships helps understanding the reaction mechanism for a chemical reaction and makes it possible to predict reaction rates and equilibrium constants.
The Brønsted catalysis equation describes the relationship between the ionization constant of a series of catalysts and the reaction rate constant for a reaction on which the catalyst operates. The Hammett equation predicts the equilibrium constant or reaction rate of a reaction from a substituent constant and a reaction type constant. The Edwards equation relates the nucleophilic power to polarisability and basicity.
