Reaction rate and diffusion coefficient of reactive Lorentz gas

The Lorentz gas reacting with the carrier gas is studied. The Chapman-Enskog method of solution of the Boltmann equation is reformulated in order to account correctly for the chemical process, The expression for the diffusion coefficient of a gas (not necessarily very light) diluted in and reacting with the carrier is derived. Calculations are performed for a model of reactive hard spheres. The rate coefficients in the reaction-diffusion equation are modified due to nonequilibrium deformation of the velocity distribution induced by the reaction. In the Lorentz range of molecular mass ratio the reaction rate constant is extremely small relative to its value calculated for the equilibrium velocity distribution. The nonequilibrium effect for the diffusion, though not so drastic, is also very significant. (C) 1998 Elsevier Science B.V. All rights reserved.