Detailed Study of HOCl + HCl → Cl2 + H2O in Sulfuric Acid

Reactive uptake coefficients for HOCl as a function of [HCl] were measured in a rotating wetted-wall flow reactor for several sulfuric acid solutions containing between 49 and 67 wt % H 2 SO 4 at 220 and 250 K. The solubility of HOCl in sulfuric acid solutions at 220 and 250 K was also measured. Using these measured solubilities, calculated HCl solubilities, and estimated diffusivities for HOCl, the second-order rate coefficients ( k II ) in the liquid were extracted. At 250 K, k II increases with increasing acid concentration, from 3 × 10 5 M -1 s -1 at 49 wt % acid to 5 × 10 6 M -1 s -1 at 67 wt %. It is suggested that the reaction may involve an initial protonation of HOCl, followed by reaction of H 2 OCl + with Cl - .