Instabilities in propagating reaction-diffusion fronts of the iodate-arsenous acid reaction

Abstract
Instabilities in propagating fronts of the iodate‐arsenous acid reaction are predicted by an empirical rate‐law model. The planar front loses stability when the ratio of the reactant diffusivity to the autocatalyst diffusivity exceeds a critical value. The relative diffusivities can be altered by introducing a reagent that reacts specifically with the autocatalyst to form an immobile complex. Experiments were carried out using a convection‐free gelled medium, loaded with reaction mixture containing complexing agent at different concentrations. Instabilities were found above a critical concentration, with the appearance of cellular fronts much like those predicted by the empirical rate‐law model.