KINETICS OF REDUCTION OF HEXACYANOFERRATE(III) BY THIOSULFATE IONS MEDIATED BY RUTHENIUM DIOXIDE HYDRATE

Andrew Mills, X.J. Li, G. Meadows

Research output: Contribution to journalArticlepeer-review

6 Citations (Scopus)

Abstract

The kinetics of reduction of hexacyanoferrate(III) by excess thiosulfate, mediated by RuO2.xH2O, are investigated. At high concentrations of S2O32- (0.1 mol dm-3) the kinetics of Fe(CN)63- reduction are first order with respect to [Fe(CN)63-] and [RuO2.xH2O] and independent of [Fe(CN)64-], [S2O32-] and [S4O62-]. At relatively low concentrations Of S2O32- (0.01 mol dm-3) and in the presence of appreciable concentrations of Fe(CN)64- and S4O62- (0.01 mol dm-3) the kinetics depend directly upon [Fe(CN)63-] and [RuO2.xH2O] and inversely upon [Fe(CN)64-]. Both sets of kinetics can be rationalised using an electrochemical model of redox catalysts in which a reversible reduction reaction [Fe(CN)63- + e- --> Fe(CN)64-] is coupled to an irreversible oxidation reaction (s2O32- - e- --> 1/2S4O62-), by a dispersion of RuO2.xH2O microelectrodes. At high concentrations Of S2O32- this model predicts that the kinetics of Fe(CN)63- reduction are controlled by the rate of diffusion of the Fe(CN)63- ions to the RuO2.xH2O particles. The kinetics observed at low concentrations of S2O32- are predicted by the electrochemical model, assuming that the Tafel slope for the oxidation Of S2O32- to S4O62- on the RuO2.xH2O particles is 56.4 mV decade-1.
Original languageEnglish
Pages (from-to)1429-1433
Number of pages5
JournalJOURNAL OF THE CHEMICAL SOCIETY-FARADAY TRANSACTIONS
Volume90
Publication statusPublished - 1994

Fingerprint

Dive into the research topics of 'KINETICS OF REDUCTION OF HEXACYANOFERRATE(III) BY THIOSULFATE IONS MEDIATED BY RUTHENIUM DIOXIDE HYDRATE'. Together they form a unique fingerprint.

Cite this