Symmetry Numbers and Statistical Factors in Rate Theory

Abstract

It is shown that for any chemical equilibrium the ratio of symmetry numbers is equal to the ratio of statistical factors; these statistical factors represent the number of different sets of products that can be formed if identical atoms in the reactant are labeled. In arriving at rate expressions one must use not simple symmetry numbers but the statistical factor l‡ for the formation of the activated complex from the reactants. This procedure takes account of the special situation that arises if the formation of the activated complex produces an optical enantiomer. The application to the Bro/nsted relationships is considered, and it is shown that Bro/nsted's original formulation is the correct one.