Kinetics of the reduction of the tetrahydroxyargentate(III) ion by sulphite in aqueous alkaline media
Date of Original Version
The reduction of Ag(OH)4- by sulphite ion to give silver(I) and sulphate in strong base has been studied by stopped-flow spectrophotometry. The reaction was found to fit a second-order rate law with a rate constant k = (9.1 ± 0.1) x 102M-1s-1 (T = 25°C, μ = 1.2 M). The estimated enthalpy and entropy of activation are 27 kJ mol-1 and - 153 J K-1 mol-1 respectively. Variation of rate with ionic strength is consistent with the interaction between mononegative Ag(OH)4- and dinegative SO32-. The redox reaction appears to proceed by a one-step oxygen atom transfer. Two kinetically indistinguishable pathways are discussed. The first involves initial attack of a sulphite oxygen at an axial silver(III) site. The second pathway involves initial interaction between sulphur(IV) and a bound hydroxyl. Sulphite oxidation by silver(III) is about 104 times faster than that of phosphite, while no reaction is observed with NO2-. © 1989.
Publication Title, e.g., Journal
Kirschenbaum, Louis J., Issifou Kouadio, and Edoardo Mentasti. "Kinetics of the reduction of the tetrahydroxyargentate(III) ion by sulphite in aqueous alkaline media." Polyhedron 8, 10 (1989). doi: 10.1016/S0277-5387(00)86527-4.