Dynamical critical phenomena in chemically reactive fluid mixtures

It is shown that the interplay between chemical reactions and thermodynamic stability gives rise to some novel phenomena manifested in a slowing down of the chemical reaction and in changes in the critical behavior of transport processes. In an n-component fluid, when all the components participate in the reaction, the rate vanishes near the critical point Tc as [(T-Tc)Tc]^γ, where γ~1.25. When one of the components does not participate in the reaction, the rate vanishes, in general, as [(T-Tc)Tc]ᵃ, where a~0.12. If more than one component is nonreactive the rate of the reaction is not sensitive to the approach to Tc. Reactive binary mixtures are treated in detail on the basis of a mode-coupling theory. In contrast to nonreactive mixtures, the shear viscosity has no divergence near the critical point. In addition, the diffusion coefficient has a different temperature and wave-vector dependence.