The oxidation of iodide by the tetrahydroxoargentate(III) ion in aqueous alkaline media
Date of Original Version
Iodide is rapidly oxidized by [Ag(OH)4]- in strongly alkaline media to give hypoiodite and AgI according to the stoicheiometric equation (i). Stoicheiometry measurements are consistent with [Ag(OH)4]- + I- → AgI + 2OH- + IO- + H2O (i) complementary two-electron redox both at excess of AgIII and excess of I-. The kinetics of the reaction are first order in the silver(III) and iodide concentrations. The second-order rate constant is 76 ± 1 dm3 mol-1 s-1(25°C, I = 1.2 mol dm-3) and the enthalpy and entropy of activation are 32.5 ± 0.6 kJ mol-1 and -100 ± 2 J K-1, respectively. While precipitation of AgI interferes with spectral measurements at lower (excess) iodide concentrations, the product formation has no effect on the kinetics of the system. The mechanism proposed involves a simultaneous two-electron transfer within an intermediate of composition [Ag(OH)4I]2-. The values of the activation parameters are similar to those of other silver(III) reactions.
Publication Title, e.g., Journal
Journal of the Chemical Society, Dalton Transactions
Kouadio, Issifou, Louis J. Kirschenbaum, and Raj N. Mehrotra. "The oxidation of iodide by the tetrahydroxoargentate(III) ion in aqueous alkaline media." Journal of the Chemical Society, Dalton Transactions 6 (1990). doi: 10.1039/DT9900001929.