On the phenomenological rate equation in a model exchange reaction

Abstract

The limits of validity of the phenomenological rate equation, and the phenomenological rate constant k f and k b are found for the exchange reaction A + BC ▪ AB + C within the framework of simple multistate models. The possibility of macroscopically long transient times is discussed. The rate constants are shown to depend on the total densities n A, n B and n C of the chemical species present in the mixture, when nonequilibrium effects are important. The distinction between a rate constant and a flux coefficient is illustrated. Differences among exchange, dissociation-recombination, and isomerization reactions in that regard are discussed.