Kinetics of the oxidation of sulfite by hydrogen peroxide in acidic solution

The kinetics of the oxidation of sulfite by hydrogen peroxide has been investigated by stopped-flow spectrophotometry over the pH range 4-8. The rate law for the oxidation of sulfite in this pH range is -d[SO_2]_T/dt = k [H^+][H_2O_2][SO_2]_T([H^+]/([H^+] K_a_2)} + k'[HA][H_2O_2][SO_2]_T{[H^+]/([H^+] + K_a_2 where HA represents all possible proton donors in solution. The reaction probably proceeds via a nucleophilic displacement by H_2O_2 on HSO_3^- to form a peroxomonosulfurous acid intermediate which then undergoes a rate-determining rearrangement.