Abstract
The reaction between I04~ and S20 32" exhibits a variable stoichiometry in acetate buffer. With a large excess of I04", the products are I03" and S042". In excess thiosulfate, I04~ is reduced to , and S4062" is formed in addition to S042". The ratio of S4062" to S042" increases with decreasing pH. In a flow reactor at high input concentrations, when the flow rate or temperature is changed or small amounts of a reactant are injected, an unbuffered reaction mixture initially in a steady state shows a strongly damped oscillatory response in pH and redox potential. At lower input concentrations, sustained pH oscillation is found. A simple model, consisting of an autocatalytic hydrogen ion production and a linear H+ consumption, allows accurate simulation of all of these kinetic behaviors.