Oxidation of thiocyanate by iron(V) in alkaline medium

摘要

The oxidation of thiocyanate by iron(V) (Fe(V)) was studied as a function of pH in alkaline solutions by a premix pulse radiolysis technique. The rates decrease with an increase in pH. The rate law for the oxidation of SCN- by Fe(V) was obtained as -d[Fe(V)]/ dt = k(10){[H+](2)/([H+](2) + K-2[H+] + K2K3)}[Fe(V)][SCN-], where k(10) = 5.72 +/- 0.19 x 10(6) M-1 s(-1), pK(2) = 7.2, and pK(3) = 10.1. The reaction precedes via a two-electron oxidation, which converts Fe(V) to Fe(III). Thiocyanate reacts approximately 10(3)x faster with iron(V) than does with iron(VI). (C) 2004 Elsevier B.V. All rights reserved.