Using laboratory studies of the high temperature kinetics of a number of sulfur gases together with a simple chemical-dynamical model of the lower atmosphere of Venus, we conclude that the relative concentrations of photochemically-produced oxidized sulfur gases (SO2, SO3) and thermochemically-produced reduced sulfur gases (COS, S2, H2S) are strongly dependent on the rate of vertical mixing. For values of the vertical eddy diffusion coefficient in excess of 104 cm2 sec-1 we predict that the reduced gases will dominate over the oxidized gases in the lower atmosphere. Measurements of the important sulfur gases by Pioneer Venus will thus provide valuable knowledge of lower atmospheric mixing in addition to furthering our understanding of the chemistry which maintains the visible sulfuric acid cloud layer.