New Modeling of Nitric Acid Dissociation Function of Acidity and Temperature.

Nitric acid is widely used for many applications. However, because of the large number of nitrogen species and the fact that for concentrations greater than 10 mol·L, its dissociation is incomplete in an aqueous medium, nitric media are very complex to describe especially in temperature. Using data from the literature and some nitrous acid analyses, it was possible to determine the balance sheet of all different aqueous nitrogen species for a total nitric acidity ranging from 1.5 to 8.5 mol·L and for temperature ranging from 50 to 95 °C with the assumption that the use of a refrigerant column makes gaseous species negligible. For this, it was necessary to determine the ionic, molecular, and solvent activity coefficients and then solve an eight equation system with nine unknowns by determining one unknown experimentally.