Kinetics of the thermal and photochemical decomposition of aquapentacyanoferrate(III) in aqueous solution

Abstract

The kinetics of the thermal and photochemical decomposition of aquapentacyanoferrate(III) ion in aqueous solution in the presence ofo-phenanthroline was studied spectrophotometrically. The first-order rate constant (k ϑ) at 30° C [I=1 M(NaCl)] for the thermal reaction is (1.49±0.13)×10−6 s−1 with ΔH ≠=(158±7)kJ mol−1 and ΔS≠=(42±4) JK−1 mol−1. The initial quantum yield for the photochemical reaction at pH=7 is independent of the light intensity and is (1.49±0.33)×10−2 mol einstein−1.