Seawater-A Test of Multicomponent Electrolyte Solution Theories. II. Enthalpy of Mixing and Dilution of the Major Sea Salts.

摘要

In a continuing effort to predict the physicochemical properties of seawater from the properties of single aqueous electrolyte solutions, the pairwise heats of mixing at constant molal ionic strength, I=1.0 ional, have been determined for the six possible pairs of salts from the set (NaC1, Na2SO4, MgC12, MgSO4) at 30 C. In addition, heats of dilution for two aqueous solutions formed from these salts and having I=1.0 ional have been determined at 30 C. In order to present the most thermodynamically consistent results, it was found necessary to apply a correction term to the relative apparent equivalent enthalpies given in the literature at 30 C. These correction terms derived from a consideration of published results on heats of dilution at very low concentrations. Further, in order to make predictions for seawater at 25 C, it was deemed desirable to refit existing heat-capacity data. The heats of mixing from this work were used with available literature data to estimate relative apparent equivalent enthalpies for the two mixtures mentioned as well as for seawater.