Oxidation of metal thiocyanates by nitric and nitrous acids. Part II. Kinetics
Abstract
The kinetics of the autocatalytic oxidation of thiocynate by nitric and nitrous acids have been followed by the increase in nitrite concentration. The rate laws observed are v=k′3[H+][HNO2][NO3–] and v=k′4[H+]2[HNO2][NO3–][SCN–] at high and low concentrations of thiocyanate respectively. The mechanism postulated involves the formation of dinitrogen tetroxide, which oxidises isothiocyanic acid to hypothiocyanous acid, which is then converted to thiocyanogen. The end-products result from the hydrolysis of thiocyanogen, and its reaction with hydrogen cyanide.