Kinetics of reactions and yield of hydrogen ions from pulse radiolysis of aqueous solutions of potassium chromate

The pulse radiolysis method has been used to determine the rate constants of reactions: H3O+ + CrO42- and HCrO4- + OH-. They are equal, respectively, to (3.1 +- 0.4) x 1011 (on condition that k(H3O+ + OH-) = 1.4 x 1011 dm3 mol-1 s-1) and (4.3 +- 0.3) x 109 dm3 mol-1 s-1. The yield of H3O+ in a bulk of the solution has been estimated from the decrease of CrO42-concentration in solutions containing oxygen. For a neutral medium it is 3.45 +- 0.5 ions/100 eV. It has been found that the yield depends on chromate concentration. This has been explained by scavenging of hydrogen ions in 'spurs' by chromate. For approximately 10-4 to 5 x 10-5 mol dm-3 solution of CrO42- the H3O+ yield is 4.25 +- 0.15 ions/100 eV. (author)