The Kinetics of the Oxidation of Iodine by Dichromate Ions in Acid Solution.

摘要

A study of the kinetics of the oxidation of I2 to iodate ion by dichromate ions in acid aqueous solution was undertaken. Ionic strength and temperature were maintained constant and the progress of the reaction was followed by spectrophotometric analysis of unreacted I2 extracted into CCl4. It was established that the reaction was 1/2 order in I2, but no exact relationship was found with hydrogen ion or any hexavalent Cr species. First order dependency on acid and H2CrO4 was found to be a possibility, or at least useful approximation, although a more precise knowledge of all Cr(VI) equilibria relations at high ionic strengths than is available would be needed for verification. A multi-step rate determining mechanism is possible, although low I2 solubility coupled with high required concentrations of other constituents limit available techniques and would probably, in this event, make determination of the complete rate expression difficult.