The oxidation of iodide by the tetrahydroxoargentate(III) ion in aqueous alkaline media
Document Type
Article
Date of Original Version
12-1-1990
Abstract
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
Issue
6
Citation/Publisher Attribution
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.