Reaction between hexacyanoferrate(III) ion and nitric and nitrous acids. Part I. Kinetics

Abstract

Hexacyanoferrate(III) ion, [Fe(CN)₆]^3–, reacts with 6 mol dm^–3 nitric acid, in the presence of nitrous acid, to form an iron cyanonitrosyl complex according to the rate law v=k[Fe(CN)₆^3–][HNO₂]^½. The reaction has been carried out in sulphuric acid, with low concentrations of nitric and nitrous acids, and k varies with h_–^½, an acidity function for ionisation of HNO₃, and [HNO₃]^½. Reaction occurs by attack of an equilibrium concentrations of nitrogen dioxide on [Fe(CN)₆]^3– ion. The intermediate species so formed undergoes a further slow reaction, following first-order kinetics.