Temperature dependence of the rate constant for the bimolecular recombination of Cl−2 in water—A pulse radiolysis study

Abstract The rate constant for the disproportionation of Cl − 2 in water has been determined for the temperature range 22–87 °C using pulse radiolysis of 0.1 M NaCl+1 mM HClO 4 aqueous solution. The rate constant for the decay of Cl − 2 has been found to be 2×(7.35±0.53)×10 8  M −1  s −1 at 22 °C (at zero ionic strength). The determined activation energy, E a =10.89±0.37 kJ mol −1 , is less than expected for diffusion-controlled reactions. A good fit to the Noyes equation (1/ k obs =1/ k diff +1/ k react ) has been obtained assuming the reaction step is activationless with k react = A ′ T .