Mechanism of the Redox Reaction of Hydroxylamine and Bromate Ions in Aqueous Hydrochloric Acid Medium

Redox kinetics of the reaction of hydroxylamine hydrochloride (H2NOH.HCl) and BrO3– was carried out in aqueous acidic medium, at temperature of 29.5 ± 0.5ºC; ionic strength µ = 1.0 mol dm–3 (NaCl), [H+] = 1.0 x 10–2 mol dm–3 (HCl). The reaction showed a stoichiometry of 1:1.3, first order kinetics in both [NH3OH+] and [BrO3–], dependence on acid concentrations, positive salt effect, catalysis due to anions and absence of evidence of intermediate complex formation. Rate equation for the reaction has been proposed as: –d[NH3OH+]/ dt =(a[H+])[ NH3OH+][ BrO3–]. The second order rate constant for the NH3OH+– BrO3– reaction was found to be 0.233 dm3 mol–1 s–1. Based on the results obtained experimentally, the outer – sphere mechanism is suggested for the reaction