INSTABILITIES IN PROPAGATING REACTION-DIFFUSION FRONTS OF THE IODATE ARSENIOUS ACID REACTION

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. © 1995 American Institute of Physics.