Thermodynamic properties of the system {yNH4Cl+(1−y)CsCl}(aq) at temperature 298.15 K

The thermodynamic properties of the mixed aqueous electrolyte system of ammonium and cesium chlorides has been studied by the hygrometric method at 298.15 K. The relative humidities of this system are measured at total molalities from 0.3 to 12 mol kg−1 for different ionic strength fractions y of NH4Cl with y=0.33, 0.50, and 0.67. The results allow the deduction of new water activities and osmotic coefficients. The experimental results are compared with the predictions of the Zdanovskii–Stokes–Robinson (ZSR), Kusik and Meissner (KM), Robinson and Stokes (RS), Lietzke and Stoughton (LSII), Reilly, Wood, and Robinson (RWR), and Pitzer models. From these measurements, the new Pitzer mixing ionic parameters are determined and used to predict the solute activity coefficients in the mixture for different ionic strength fractions of NH4Cl.