Reaction kinetics in the absorption of chlorine into aqueous media

It was established that chlorine reacts with both water and hydroxyl ions. At a short reaction time when the pH was less than 3 the reversible reaction of chlorine and water controlled the absorption rate. From pH 3 to 10.5 the forward reaction predominated and yielded an apparent first‐order rate constant of 20.9 sec. −1 at 25°C. Between pH 10.5 and 12.5 the reaction of chlorine with hydroxyl ions occurred simultaneously with the chlorine‐water reaction. Above pH 12.5 the second‐order reaction between chlorine and hydroxyl ions became controlling and the reaction‐rate constant was evaluated to be in the order of 10 6 liters/(mole)(sec.) at 25°C. These ionic reactions of chlorine were further interpreted through the collision and transition state theories. Certain important quantities with regard to the reaction characteristics were derived from the experimental data.