Nonequilibrium effects on the rate of bimolecular chemical reaction in a dilute gas

The perturbation solution of the Boltzmann equation in a dilute gas shows that the rate constant of chemical reaction A+A ⇄ B+B is diminished due to nonequilibrium effects. For the line-of-centers model, the relative decrease η of the reaction rate can reach even nearly 45% (for a small reduced threshold energy ε* and a large molar fraction xB). For slow reactions this method is valid and η does not depend on xB. The appropriate equilibrium expressions for reaction rate (with: (a) the temperature of the system T, (b) the nonequilibrium Shizgal–Karplus temperatures TA and TB) are used for this analysis.