Speciation in aqueous solutions of nitric acid estimated within the binding mean spherical approximation (BiMSA)

This work is aimed at a description of the thermodynamic properties of highly concentrated aqueous solutions of nitric acid salts at 25 degrees C. The predictive capability of the binding mean spherical approximation (BIMSA) was examined. First, Raman spectroscopy was used to study the proportion of associated nitric acid as a function of concentration. The corresponding apparent association constant values were compared with literature values. Besides, the BIMSA model led to an assessment of the degree of association. The so-calculated amount of associated nitric acid coincides accurately with our Raman experimental results up to a high concentration of acid. (authors)