Collect. Czech. Chem. Commun. 1993, 58, 538-546

Kinetics and Mechanism of Oxidation of Selenium(IV) by Permanganate Ion in Aqueous Perchlorate Solutions

Refat M. Hassan, Sahr A. El-Gaiar and Abd El-Hady M. El-Summan

Department of Chemistry, Faculty of Science, Assiut University, Assiut 71516, Egypt


The kinetics of permanganate oxidation of selenium dioxide in perchloric acid solutions at a constant ionic strength of 2.0 mol dm-3 has been investigated spectrophotometrically. A first-order reaction in [MnO4-] and fractional order with respect to selenium(IV) were observed. The reaction rate was found to be pH-independent at lower acid concentrations ([H+] < 0.5 mol dm-3) and was acid-catalyzed beyond this range. Addition of Mn2+ and F- ions leads to the prediction that MnO4- is the sole reactive species in the oxidation process. A tentative reaction mechanism consistent with the reaction kinetics has been proposed.