Osmotic and Activity Coefficients of the Ternary NH4I+ NaI + H2O System at 298.15 K

The present work purposes on isopiestic vapor pressure measurements at 298.15 K for the ternary system {yB NH4I+ yC NaI}(aq). Measurements were made for both pure solutions and for the mixed solutions with various ionic strength fractions of NH4I ( 0.25, 0.50 and 0.75 )and for molalitis up to about 4.51〖 molkg-1. The experimental results were treated by extended forms of Pitzer and McKay-Perring methods. Based on the optimized values of the interaction parameters of Pitzer model, activity coefficients of the both constituent salts were calculated and compared well with those evaluated by McKay-Perrig method.