Kinetics and mechanism of the oxidation of pentathionate ion by chlorine dioxide in a slightly acidic medium

Li Xu, György Cseko, Andrea Petz, Attila K. Horváth

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Abstract

The chlorine dioxide-pentathionate reaction has been studied at a slightly acidic medium by conventional UV-vis spectroscopy monitoring the absorbance at 430 nm. We have shown that pentathionate was oxidized to sulfate, but chlorate is also a marginal product of the reaction besides the chloride ion. The stoichiometry of the reaction can be established as a linear combination of two limiting stoichiometries under our experimental conditions. Kinetics of the reaction was found to be also complex because initial rate studies revealed that formal kinetic orders of both the hydrogen ion and chlorine dioxide is far from unity. Moreover, log-log plot of the initial rate against pentathionate concentration indicated a nonconstant formal kinetic order. We also observed a significant catalytic effect of chloride ion. Based on our observations and simultaneous evaluation of the kinetic curves, an 11-step kinetic model is obtained with 6 fitted rate coefficients. A relatively simple rate equation has also been derived and discussed.

Original languageEnglish
Pages (from-to)1293-1299
Number of pages7
JournalJournal of Physical Chemistry A
Volume118
Issue number8
DOIs
Publication statusPublished - Feb 27 2014

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ASJC Scopus subject areas

  • Physical and Theoretical Chemistry

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