Some physico-chemical properties of the system nitric acid--nitrogen dioxide--water. The kinetics of the thermal decomposition of nitric acid in the liquid phase. Electrolytic conductance of the ternary system nitric acid--nitrogen dioxide--water at 32 degrees F and atmospheric pressure

Abstract

Part I. The investigation of the kinetics of the decomposition of the liquid phase of nitric acid has indicated that the reaction probably proceeds by way of the unimolecular decomposition of dinitrogen pentoxide which exists in the pure acid. The effects of several inorganic additives in suppressing the rate of decomposition are in agreement with the postulate involving dinitrogen pentoxide. The magnitude of the inhibition of the decomposition by various additives has been found to be insufficient to prevent the eventual attainment of high equilibrium pressures resulting from decomposition when nitric acid is stored in closed containers. The solubility of oxygen in fuming nitric acid has been determined for oxygen pressures up to 21 atmospheres in the temperature range between 35[degrees] and 70[degrees]C. Under these conditions, the solubility of oxygen was found to increase with an increase in temperature. Part II. The electrolytic conductance of the system nitric acid--nitrogen dioxide--water in the liquid phase was measured at 0[degrees]C and a pressure of 1 atmosphere for compositions containing more than 0.80 weight fraction nitric acid. The conductance of the associated binary systems nitric acid--water and nitric acid--nitrogen dioxide has been measured over the entire range of compositions from 0 to 1.00 weight fraction nitric acid. The conductance measurements offer additional proof of the self-ionization of pure nitric acid and of the ionization of nitrogen dioxide dissolved in nitric acid.