Evolution of Chemically Induced Unstable Density Gradients Near Horizontal Reactive Interfaces

We study the evolution of concentration and density profiles in the course of chemical reactions near horizontal interfaces. Examples include first-order reaction with a catalytic surface, second-order reaction in a double-diffusive liquid-liquid interface, gas-liquid or liquid-membrane-liquid reactions, and the irradiation of a photoactive liquid interface. Our main observation is that, quite often, the resulting density profiles indicate potentially unstable hydrodynamic configurations that may lead to mass distribution through spontaneous convections, i.e., much faster than diffusion.