The thiosulfate-iodate reaction has been studied spectrophotometrically in slightly acidic medium at 25.0 ± 0.1 °C in acetate/acetic acid buffer by monitoring the absorbance at 468 nm at the isosbestic point of iodine-triiodide ion system. The formation of iodine after the Landolt time follows a rather complex kinetic behavior depending on the pH and on the concentration of the reactants as well. It is shown that the key intermediate of the reaction is I2O2, its equilibrium formation from the well-known Dushman reaction along with their further reactions followed by subsequent reactions of HOI, HIO2, S2O3OH -, and S2O3I- adequately accounts for all the experimentally measured characteristics of the kinetic curves. A 19-step kinetic model is proposed and discussed with 13 fitted and 7 fixed parameters in detail.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry