Modeling nitronium ion concentrations in HNO3-H2SO4-H2O mixtures

Nitronium ion (NO2+) data reported by Zaman (1972), for HNO3-H2SO4-H2O mixtures have been modeled using four ionization reactions that produce NO2+, H3O+, HSO4-, and NO3-. Zaman had measured NO2+ concentrations for 62-66 acid mixtures at 20 degrees, 30 degrees, and 40 degrees C. The equilibrium constants for the four reversible reactions were calculated using a non-linear least squares programming technique. The predicted NO2+ concentrations agree well with the experimental data. The application of the results to industrial nitrations and the extrapolation of the findings to mixed acids containing N2O5 and SO3 are discussed.