The kinetics and mechanisms of some redox reactions involving nitrogen(III)

Abstract

This work is concerned with the oxidation of nitrogen(III) by-chlorate, bromate and iodate in aqueous solution.

The introduction reviews background information concerning the reactants in isolation, considers relevant speculations about their reactivities and surveys previously published work on the reactions. These earlier kinetic studies were made before many of the concepts now applied to solution kinetics were available.

It has been shown experimentally that the reactions proceed at conveniently measurable rates under acid conditions. Concerning the reduction of chlorate by "nitrite"?, which was examined in the pH range (1--2), the kinetics show that it is of the first order with respect to chlorate, nitrous acid and hydrogen ions. The reduction of bromate by "nitrite", which was examined in the pH range (2-1--3.2), is of first order with respect to bromate, nitrous acid and hydrogen ions. The reduction of iodate by "nitrite", which was examined in the acidity range (1.42--2.26M), is more complex in its kinetics.

The rate of decomposition of nitrous acid alone, under similar conditions, was also studied. The effects on reaction rate of change in ionic strength, temperature and addition of various simple salts and products have been studied and the stoichiometry of each reaction, under conditions similar to those used in the kinetic measurements, has been worked out. Efforts were made to identify intermediates and reaction products via use of mass, e.s.r., visible and ultraviolet spectroscopy besides qualitative analysis.

Possible mechanisms for the reactions with nitrous acid are discussed.