Experimental and Modeling Study of Oscillations in the Chlorine Dioxide-Iodine-Malonic Acid Reaction

Istvan Lengyel, Gyula Rábai, Irving R. Epstein

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At pH 0.5-5.0, a closed system containing an aqueous mixture of chlorine dioxide, iodine, and a species such as malonic acid (MA) or ethyl acetoacetate, which reacts with iodine to produce iodide, shows periodic changes in the light absorbance of I3-. This behavior can be modeled by a simple scheme consisting of three component reactions: (1) the reaction between MA and iodine, which serves as a continuous source of I-; (2) the reaction between CIO2- and I-, which acts as a source of CIO2-; and (3) the self-inhibited reaction of chlorite and iodide that kinetically regulates the system. The fast component reaction between chlorine dioxide and iodide ion was studied by stopped-flow spectrophotometry. The rate law is-[CIO2*]/dt = 6 × 103 (M-2 s-1)[CIO2][I-). A two-variable model obtained from the empirical rate laws of the three component reactions gives a good description of the dynamics of the system. The oscillatory behavior results not from autocatalysis but from the self-inhibitory character of the chlorite-iodide reaction.

Original languageEnglish
Pages (from-to)9104-9110
Number of pages7
JournalJournal of the American Chemical Society
Issue number25
Publication statusPublished - Dec 1990


ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

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