Three autocatalysts and self-inhibition in a single reaction

A detailed mechanism of the chlorite-tetrathionate reaction

A. Horváth, I. Nagypál, Irving R. Epstein

Research output: Contribution to journalArticle

35 Citations (Scopus)

Abstract

The chlorite-tetrathionate reaction has been studied spectrophotometrically in the pH range of 4.65-5.35 at T = 25.0 ± 0.2°C with an ionic strength of 0.5 M, adjusted with sodium acetate as a buffer component. The reaction is unique in that it demonstrates autocatalysis with respect to the hydrogen and chloride ion products and the key intermediate, HOCl. The thermodynamically most-favorable stoichiometry, 2S4O6 2- + 7ClO2- + 6H2O → 8SO 42- + 7Cl- + 12H+, is not found. Under our experimental conditions, chlorine dioxide, the chlorate ion, or both are detected in appreciable amounts among the products. Initial rate studies reveal that the formation of chlorine dioxide varies in an unusual way, with the chlorite ion acting as a self-inhibitor. The reaction is supercatalytic (i.e., second order with respect to autocatalyst H+). The autocatalytic behavior with respect to Cl- comes from chloride catalysis of the chlorite-hypochlorous acid and hypochlorous acid-tetrathionate subsystems. A detailed kinetic study and a model that explains this unusual kinetic behavior are presented.

Original languageEnglish
Pages (from-to)9877-9883
Number of pages7
JournalInorganic Chemistry
Volume45
Issue number24
DOIs
Publication statusPublished - Nov 27 2006

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Hypochlorous Acid
Ions
dioxides
chlorine
Chlorates
autocatalysis
chlorates
Sodium Acetate
ions
acids
hydrogen chlorides
Kinetics
Hydrochloric Acid
kinetics
hydrogen ions
products
Ionic strength
Stoichiometry
inhibitors
Catalysis

ASJC Scopus subject areas

  • Inorganic Chemistry

Cite this

Three autocatalysts and self-inhibition in a single reaction : A detailed mechanism of the chlorite-tetrathionate reaction. / Horváth, A.; Nagypál, I.; Epstein, Irving R.

In: Inorganic Chemistry, Vol. 45, No. 24, 27.11.2006, p. 9877-9883.

Research output: Contribution to journalArticle

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