Nonlinear extended thermodynamics of reaction kinetics in liquids

Abstract

In a fluid phase with a single chemical reaction, the state variables include volume, temperature and the numbersN i of molecules of each species. To these the extended nonequilibrium thermodynamics adds the reaction rate,J. The force Φ = - δF/δJ, whereF is the Helmholtz function, can be calculated by comparing a model kinetic equation forJ with the canonical expression which relatesJ to a sum of forces, utilising to this end a reciprocity relation. Prom Φ, via the integrability conditions for dF, one calculates theO(J 2) contributions to pressure and internal energy. For a steady-dissociation reaction such as we might simulate on a computer for liquid nitrogen exposed to radiation, theO(J 2) contribution toP is predicted to be large enough to observe. By comparing chemical potentials of a steady-state liquid and gas in relative equilibrium with respect to diffusive particle exchange, one can relate the reaction rates in the two phases. This can be used in a computer simulation to extract information about the liquid kinetics.