Travelling waves in the iodate-arsenous acid system

The equations describing travelling waves in the iodate-arsenous acid reaction are discussed, with kinetics based on the Dushman-Roebuck scheme. These equations are used to show how the structure of the wave (its propagation speed and final reaction products) depends on the stoichiometry factor S-0, the initial concentration of arsenous acid relative to iodate. Different forms are seen in the ranges 0 < S-0 < 5/2, 5/2 < S-0 < 3 and S-0 > 3. An asymptotic analysis, based on a large parameter arising in the system, is undertaken. This shows that wave structures and propagation speeds are different in these three ranges of S-0.