Nonequilibrium velocity distributions and reaction rates in fast highly exothermic reactions

Abstract

The nonequilibrium velocity distributions and reaction rates in fast highly exothermic reactions with a low activation energy ${\mathrm{\epsilon *}}_f{\mathrm{/k\hspace{0.17em}T}}_0\text{≤slant 5}$ , a high steric factor $\text{P ≥slant 0.1}$ , and a large heat of reaction Q*/k T₀ ∼ O (10), are investigated by solving the semiclassical Boltzmann equation with a Monte Carlo method. The explicit time‐dependent velocity distribution functions and reaction rates from the initial equilibrium to the final chemical equilibrium are obtained for a model system, where the chemical species without internal degrees of freedom undergo a bimolecular single reversible reaction. The velocity distributions and the reaction rates indicate significant departures from equilibrium. The extent of departure of the reaction rate from the equilibrium rate increases with the heat of reaction and the activation energy and can be greater than 100%.