The dependence of scaling law on stoichiometry for horizontally propagating vertical chemical fronts.

Horizontally propagating fronts in the iodate-arsenous acid reaction are investigated experimentally in a vertically oriented Hele-Shaw cell by varying the height of liquid layer for various stoichiometry. At the preset conditions, a stable pattern develops which can be characterized by its mixing length defined as the standard deviation of the front position in the direction of propagation. The mixing length scales with the height of the reaction vessel, and although the exponent significantly changes by varying the ratio of the reactants, it has a universal value when the reaction front is thin and simple convection arises.