A new equation for predicting the density of multicomponent aqueous solutions conforming to the linear isopiestic relation

Abstract

The linear isopiestic relation has been used together with well-known thermodynamic equations to establish a new simple predictive equation for density. This equation can provide the density for multicomponent solutions conforming to the linear isopiestic relation using only information on the corresponding binary sub-systems of equal water activity. No additional empirical parameters are involved. The predictive capability of the equation has been tested by comparison with the density measurements for the ternary systems NaCl–KCl–H₂O, NaCl–CaCl₂–H₂O, KCl–CaCl₂–H₂O, NaCl–MgCl₂–H₂O, NaCl–Na₂SO₄–H₂O, NaCl–MgSO₄–H₂O and NaBr–KCl–H₂O and their corresponding binary subsystems over the whole experimental composition ranges at 298.15 K. The agreement between the predicted and measured densities is excellent over the entire experimental composition ranges.