Correlation of Osmotic Coefficient Data for ZnSO_4(aq) at 25 deg C by Various Thermodynamic models

摘要

The available literature data on the osmotic coefficient of ZnSO_4(aq) at 25 deg C in the modality range from 0.1 to 4.3 mol-kg~(-1) and new experimental data from 1.2 to 2.9 mol-kg~(-1), at the same temperature, are presented. Selected values of the osmotic coefficient from all the data are analyzed using the Clegg-Pitzer-Brimblecombe model, the extended Pitzer model, and a semiempirical equation comprising a power series in modality added to the Debye-Huckel limiting law. The extended Pitzer equation and the Clegg-Pitzer-Brimblecombe equations give the bet results in fitting the osmotic coefficient data. All three models are used to calculate ZnSO_4 activity coefficients at 25 deg C in dilute solutions (<0.1 mol-kg~(-1)) for comparison with published values.