Kinetics of oxidation of hydrobromic acid by nitric acid in the presence of nitrous acid

Abstract

The rate of formation of bromine on treating nitric acid with hydrobromic acid has been investigated at 2, 25, and 50 °C. The order of reaction is 1·5 with respect to nitrous acid and between 1 and 2 with respect to bromide ion. The rate is strongly dependent on acid and neutral salt concentrations, but the influence of nitrate-ion concentration is small. A proposed mechanism, in accord with the data, is based on fast equilibria forming an intermediate which reacts further in a slow step. The equilibria are reversed by high water concentrations; cations, by hydration, reduce the water concentration and increase the rate. Hydration numbers of salts can be calculated from this increase in rate.