Statistical mechanics of deuterium exchange reactions : relationships between equilibrium constants and enthalpies of reaction

Abstract

Bertrand and Burchfield proposed that the equilibrium constants K and the (standard) enthalpies ΔH of isotopic exchange reactions are related by the equation

in which K_stat is the statistical (random) equilibrium constant. The application of this equation to deuterium exchange reactions for which experimental K and ΔH values are available suggests that it is a good approximation at 298 K. In this paper we present a statistical mechanical analysis to account for the success of the equation and to point out its limitations.