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 $T_c$ as ${\left[\frac{(T-T_c)}{T_c}\right]}^{\gamma }$, where $\gamma \sim 1.25$. When one of the components does not participate in the reaction, the rate vanishes, in general, as ${\left[\frac{(T-T_c)}{T_c}\right]}^a$, where $a\sim 0.12$. If more than one component is nonreactive the rate of the reaction is not sensitive to the approach to $T_c$. 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.