KINETICS OF OXIDATION OF HYDRAZINIUM ION BY HEXACHLOROIRIDATE(IV)

Kinetics of the oxidation of hydrazinium ion by hexachloroiridate(IV) have been studied spectrophotometrically in perchloric acid medium in the temperature range 30-45°C. The reaction is first order with respect to iridium(IV) whereas the order with respect to hydrazinium ion is less than 1. Hydrogen ion decreases the rate of oxidation. The additions of salts have accelerating effects on the rate of reaction. The rate also increases with decreasing dielectric constant. The reaction is not retarded by the hexachloroiridate(III) ions produced in the reaction. The empirical rate equation is[FORMULA OMMITED] Ea and ΔS‡ were found to be 96.8 kJ.mol-1 and -1.2 J K-1, respectively. ΔH and ΔS° associated with K were found to be -69 kJ mol-1 and -205 J K-1, respectively. © 1979, American Chemical Society. All rights reserved.