A LASER PHOTOLYSIS STUDY OF THE REACTION OF SO4- WITH CL- AND THE SUBSEQUENT DECAY OF CL2- IN AQUEOUS-SOLUTION

Kinetic spectroscopic techniques were employed to investigate the reactions of the SO4- and Cl2- radicals following photolysis of K2S2O8-NaCl solutions at 248 nm. The extinction coefficient of SO4- was estimated to have a value of (1.6 ± 0.1) × 103 M-1 cm-1 (base 10) at 450 nm, its wavelength of maximum absorbance. A mechanism is proposed which accounts for the observed decay of Cl2- in aqueous solution. Several rate coefficients have been determined at 20°C: k(SO4- + Cl-) = (2.7 ± 0.4) × 108 M-1 s-1 (at zero ionic strength), 2k(Cl2- + Cl2-) = (1.4 ± 0.2) × 109 M-1 s-1 (at zero ionic strength), k(Cl2- + H2O) = (1.3 ± 0.1) × 103 s-1, and k(Cl + H2O) = (2.5 ± 0.2) × 105 s-1. © 1990 American Chemical Society.