Pulse radiolysis of aqueous thiocyanate and iodide solutions

Abstract

The transient absorption produced by the pulse radiolysis of CNS^– is shown to be due to (CNS)₂ formed by the reactions : [graphic omitted] The rate constants of reactions (1), (2) and (3) at 22°C determined from kinetic and equilibrium measurements are 2.8 × 10¹⁰, 7.0 × 10⁹ M^–1 sec^–1 and 3.4 × 10⁴ sec^–1, respectively. For iodide ion, which forms I₂ in the same way, the equilibrium constant for I₂ formation is 1.13 × 10⁵ M^–1. The corresponding kinetic constants cannot be determined as accurately as for CNS^– but are estimated to be 3.4 × 10¹⁰, 7.6 × 10⁹ M^–1 sec^–1 and 6 × 10⁴ sec^–1.