Simple Models for Nonequilibrium Effects in Bimolecular Chemical Reaction in a Dilute Gas

Two models for reactive cross sections are introduced to analyze nonequilibrium effects connected with proceeding of the bimolecular chemical reaction A + A ↔ B + B in a dilute gas: 1. Line-of-Centers model LC, 2. the reverse model rLC leading to negative values of the Arrhenius activation energy. The perturbation method of solution of the Boltzmann equation is used to obtain analytical expressions for the rate constant of chemical reaction and for the nonequilibrium Shizgal-Karplus temperatures. It is shown that if the molar fraction of product is large enough the relative change of the rate of chemical reaction is constant, i.e. does not depend on the molar fraction. Replacing the equilibrium temperature by the nonequilibrium one (depending on the molar fraction) in the equilibrium equations for forward and reverse rate constants confirms these results. (author)