Kinetics and mechanism of oxidation of hydrazinium ion with peroxomonophosphoric acid in acid perchlorate solutions and role of trace iodide ions

The reaction of peroxomonophosphoric acid and hydrazinium ion in acid perchlorate solutions occurs as per stoichiometry (i), and the rate law (ii) at large [N 2 H 5 + ],where K′ d is the first acid dissociation constant of H 3 PO 5 and k 1 and k 2 are rate constants found to be 2.6 × 10 −4 s −1 and 5.0 × 10 −2 M −1 s −1 , respectively, at 35°. The reaction is greatly catalyzed by iodide ions. The mechanism involves a redox cycle I − /I 2 and the rate is independent of [N 2 H 5 + ] in the presence of iodide ions. K′ d was found to be 0.55 M −1 and independent of temperature.