Temperature dependence of the rate constant for hydrogen atom reaction with Cl2-• in water by pulse radiolysis of aqueous HCl solution

The temperature dependence of the rate constant for the reaction of dichloride anion radical (Cl-2(-center dot)) with atomic hydrogen (H-center dot) in water up to 75 degrees C has been determined by pulse radiolysis of deaerated 0.1 M HCl solution. The room temperature value is (6.1 +/- 0.6) x 10(9) M-1 s(-1). The activation energy of (13.2 +/- 0.6) kJ mol(-1) is less than 16.7 kJ mol(-1), expected for the diffusion-controlled reaction. Based on the temperature dependence of the rate constant for the reactions H-center dot + Cl-2(-center dot) and H-center dot + Cl-2, derived in this work, and on that reported earlier (Szala-Bilnik et al., 2014) for Cl-2(-center dot) + Cl-2(-center dot), we show that a value of (10 +/- 2) M-1 s(-1) determined by Hartig and Getoff (1982) for k (H-center dot + H2O) in water at 25 degrees C is overestimated by at least two orders of magnitude. (C) 2015 Elsevier Ltd. All rights reserved.