Onset of convective instabilities in binary liquid mixtures with fast chemical reactions

Analytic expressions are found for the criteria for the onset of stationary and oscillatory convection in binary mixtures with chemical reaction. The reaction is assumed to be fast compared with the diffusion rate. It is found that both stationary and oscillatory instabilities can occur as the first bifurcation, depending on the sign and the value of the heat of reaction. An endothermic polymerization, which produces the heavy component (polymer) near the warm boundary, is an example of a reaction that can cause either stationary or oscillatory convection when the system is heated from above or below, respectively. Numerical estimates are given for both stationary and oscillatory instabilities.