Classical Thermodynamics and Reaction Rates Close to Equilibrium

Abstract

For reversible reactions close to equilibrium the net reaction rate (rf—rb) is shown to be proportional to ΔX, where X is any one of the thermodynamic functions, e.g., the Gibbs free energy, F, governing equilibrium under the conditions of the reaction, e.g., (rf—rb)=rf·—ΔF /RT. The derived relationships are independent of the manner in which small displacements from equilibrium may be brought about. Equations are derived by which the magnitude of the forward (or backward) reaction rate at equilibrium may be determined with the aid of observations of the net reaction rate close to equilibrium. Since the magnitude of the former is a function of the kinetics of the reaction, measurements of the net reaction rate near equilibrium over a range of conditions may be used within specified limits to determine the kinetics of reversible reactions.