Pulse radiolysis of aqueous thiocyanate and iodide solutions

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.