Chlorine Dioxide-Iodine-Sodium Thiosulfate Oscillating Reaction Investigated by the UV-Vis Spectrophotometric Method

A new chlorine dioxide-iodine-sodium thiosulfate chemical oscillatory reaction was studied by the UV-Vis spectrophotometric method. The initial concentrations of sodium thiosulfate, chlorine dioxide, iodine, sulfuric acid, and pH have great influences on the oscillations observed at wavelength 238 nm. The oscillations occur as long as the reactants are mixed. The amplitude and the number of oscillations are associated with the initial concentrations of reactants. The equations for the triiodide ion reaction rate changes with reaction time and the initial concentrations in the oscillation stage are an attenuation sine function. Based upon the experimental data in this work and in the literature, a plausible reaction mechanism was proposed for the oscillation reaction.