Electron transfer between trans-dihydroxotetraoxoosmate(VIII) and thiosulfate. A kinetic study in aqueous alkaline media

✍ Scribed by Rama Krushna Panda; Gautam Neogi; D. Ramaswamy

• Publisher: John Wiley and Sons
• Year: 1981
• Tongue: English
• Weight: 513 KB
• Volume: 13
• Category: Article
• ISSN: 0538-8066
• DOI: 10.1002/kin.550131002

✦ Synopsis

The kinetics of oxidation of thiosulfate to tetrathionate by trans-dihydroxotetraoxoosmate(VII1) in aqueous alkaline media have been studied. The oxidation follows a rate expression

where K a is the formation constant of trans-dihydroxotetraoxoosmate (VIII), and K2 and ka, respectively, represent the formation constants of the intermediate complex involving Os(VII1) and S20;and its decomposition constant. The K h , K P , and k3 values have been computed to be (19.5 f 3) dm3/mol, (6.12 f 0.5) and (3.32 f 0.3) X lo-' dm3/mol s a t 303 K, and I = 0.32 mol/dm3, respectively. The rate law is consistent with a mechanism envisaging the equilibrium formation of an intermediate complex involving Os(VII1) and S*O$-, followed by a rate-determining decomposition of the complex with concomitant electron transfer.