Abstract
The chlorine−dioxide-tetrathionate reaction was studied spectrophotometrically in the pH range 4.55−5.55 at 25.0 ± 0.2 °C and 0.5 M ionic strength adjusted with sodium acetate as a buffer component. The stoichiometry was found to be S4O6 2- + 4•ClO2 + 5H2O → 4SO4 2- + ClO3 - + 3Cl- + 10H+ with small deviations at high excess of chlorine dioxide with no chloride ion initially present. The initial presence of chloride not only affects the stoichiometry but also accelerates the reaction. A 14-step mechanism, including four known and two newly proposed intermediates, is suggested to describe the observed behavior of the system.