The Kinetics and Mechanism of the Chlorine Dioxide−Iodide Ion Reaction

The oxidation of iodide ion by chlorine dioxide has been studied by stopped-flow techniques at I = 1.0 M (NaClO4). The following two-term rate law was confirmed for the reaction:  −d[ClO2]/dt = k I[ClO2][I-] + k II[ClO2][I-]2. The rate constants at 298 K and the activation parameters are k I = (1.87...

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Published in:Inorganic chemistry 1997-06, Vol.36 (12), p.2494-2497
Main Authors: Fábián, István, Gordon, Gilbert
Format: Article
Language:English
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Summary:The oxidation of iodide ion by chlorine dioxide has been studied by stopped-flow techniques at I = 1.0 M (NaClO4). The following two-term rate law was confirmed for the reaction:  −d[ClO2]/dt = k I[ClO2][I-] + k II[ClO2][I-]2. The rate constants at 298 K and the activation parameters are k I = (1.87 ± 0.02) × 103 M-1 s-1, ΔH I ⧧ = 35.4 ± 0.7 kJ/mol, ΔS I ⧧ = −63.5 ± 2.3 J/(mol K), k II = (1.25 ± 0.04) × 104 M-2 s-1, ΔH I I ⧧ = 36.7 ± 1.3 kJ/mol, ΔS I I ⧧ = −43.2 ± 4.6 J/(mol K). Both the second- and third-order paths are interpreted in terms of an outer-sphere electron-transfer mechanism. The calculations based on the Marcus theory yield k I = 1358 M-1 s-1 for the second-order path.
ISSN:0020-1669
1520-510X
DOI:10.1021/ic961279g