Correlation of osmotic coefficient data for ZnSO4(aq) at 25 degrees C by various thermodynamic models

Abstract

The available literature data on the osmotic coefficient of ZnSO4(aq) at 25degreesC in the molality 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 molality added to the Debye-Huckel limiting law. The extended Pitzer equation and the Clegg-Pitzer-Brimblecombe equations give the best results in fitting the osmotic coefficient data. All three models are used to calculate ZnSO4 activity coefficients at 25degreesC in dilute solutions (<0.1 mol-kg(-1)) for comparison with published values.