The Mechanism of Decomposition of Hydrogen Peroxide by Iodine in Acid Solutions. The Rates of Associated Reactions

Abstract

Abstract For the purpose of isolating elementary reactions responsible for the decomposition of hydrogen peroxide by iodine and its compounds, the reaction at 50°C of acid solutions containing I2, I−, HIO, etc. with [I−] and [I2] controlled by use of TlI(s) and I2(s) was studied. The rates of the evolution of oxygen, consumption of hydrogen peroxide and production of H+ were subjected to measurement and led to a formulation of a complex mechanism consisting of the following reactions: HIO2+H2O2→HIO+H2O+O2; H2OI++H2O2→HIO2+H++H2O; HIO+H2O2→H++I−+H2O+O2; HIO2+H++I−→2HIO; H2OI+\ightleftharpoonsHIO+H+; I−+H++H2O2→HIO+H2O; and I2+H2O\ightleftharpoonsHIO+H++I−. Absolute or relative rate constants for the first four reactions were evaluated by using equilibrium and rate constants of the others.