A Modified Kinetic Model for the Peroxydisulfate‐Iodide Reaction

One kinetic model for the oxidation of iodide ion by peroxydisulfate ion in aqueous solution is proposed. The reaction is regarded as \documentclass{article}\pagestyle{empty}\begin{document} {\rm S}_2 {\rm O}_8^{2 -} + {\rm I}^ - {\rm IS}_2 {\rm O}_8^{3 -} \end{document} , followed by the reaction \documentclass{article}\pagestyle{empty}\begin{document} {\rm IS}_2 {\rm O}_8^{3 -} + {\rm I}l_2 + 2{\rm SO}_4^{2 -} \end{document} . If the initial rates V are obtained from the formation of the iodine molecules, the reaction rate constant k 1 and the ratio k 2 / k ‐1 can be estimated by plotting the values of [S 2 O 8 2− ][ I − ]/ V against that of 1/[ I − ]. The extrapolated value for k 1 is 2.20×10 −2 L / mol‐sec and k 2 / k ‐1 is calculated to be 4.25×10 2 mol / L at 27°C in a solution with an ionic strength of 0.420.