The Iodine—Thiosulfate Reaction: a Pulse-Radiolysis Study and Spectrophotometric Evidence for the Intermediates I2S2O32- and IS203-.

Abstract

Spectroscopic evidence for I₂S₂O₃^2- and IS₂O₃^-, postulated as intermediates in the iodine{thiosulfate reaction, has been obtained by using the technique of pulse radiolysis to oxidize iodide to I₃^- in the presence of thiosulfate. The spectra show blue shifts with respect to I₃^- and I₂ respectively. The kinetics of the reaction over a range of concentrations different from those reported by Scheper and Margerum have also been studied and further evidence for their quantitative scheme has been obtained; a change predicted by their model, but not detected by them, in kinetic order in S₂O₃^2- at low thiosulfate and high iodide concentrations has been found.