EQUILIBRIUM PARTIAL PRESSURES AND MEAN ACTIVITY AND OSMOTIC COEFFICIENTS OF 0-100-PERCENT NITRIC-ACID AS A FUNCTION OF TEMPERATURE

Rational activity and osmotic coefficients and Henry's law constants KHx (for the reaction HNO3(g) = H+(aq) + NO3-(aq)), given as functions of temperature, enable p(H2O) and p(HNO3) to be calculated from -60 to 120°C, 0-100% HNO3. Apparent molal enthalpies, heat capacities, and activity coefficients (derived from electromotive force (emf), freezing point, and partial pressure data) are represented with the use of the species-interaction models of Pitzer. Equations for the partial molal functions are given. The Henry's law constant is evaluated from p(HNO3) data at 298.15 K, tabulated heats of formation, and heat capacities. Calculated p(H2O) and p(HNO3) over the entire concentration range agree with available data over 5 orders of magnitude of p(H2O) and 7 orders of magnitude of p(HNO3). © 1990 American Chemical Society.