ISOPIESTIC INVESTIGATION OF THE OSMOTIC AND ACTIVITY-COEFFICIENTS OF AQUEOUS NABR AND THE SOLUBILITY OF NABR2H2O(CR) AT 298.15-K - THERMODYNAMIC PROPERTIES OF THE NABR+H2O SYSTEM OVER WIDE RANGES OF TEMPERATURE AND PRESSURE

Isopiestic vapor-pressure measurements have been performed for aqueous solutions of well-characterized high-purity NaBr from 1.9551 to 9.477 8 mol.kg(-1) at 298.15 K; the highest five molalities correspond to su persaturated concentrations. Solubilities have also been determined by this method. A few equilibrations were made between solutions of NaCl and H2SO4 to refine the osmotic coefficients of H2SO4 at high molalit ies. These isopiestic results for NaBr have been combined with other e xperimental thermodynamic quantities (vapor pressures, activity coeffi cients, solubilities, freezing temperatures, and volumetric and calori metric measurements) to yield revised parameters for an extended form of Fitter's equation applicable over wide ranges of molality, temperat ure, and pressure. It was not possible to obtain a complete consistenc y between the experimental results for either the NaBr + H2O system or the NaCl + H2O system with entropies from the CODATA Key Values for T hermodynamics.