Phase Equilibrium for the Aqueous Ternary Systems NH4+, Sr2+(Ca2+)//Cl--H2O at T =298K

摘要

Data are presented on the solubilities, densities, and refractive indices of the aqueous ternary systems NH4+, Sr2+(Ca2+)//Cl--H2O at 298K by using the isothermal dissolution method. Stable phase diagrams and the diagrams of the physicochemical properties (densities and refractive indices) depending on the composition were constructed on the basis of measured data. The solid phase was determined using Schreinemakers' wet residue method and X-ray diffraction method. Results show that these two systems which consist of one invariant point, two univariant curves and two regions of simple salts' crystallization, belong to simple type, without solid solution or double salt formed. In the stable phase diagram of Ca2+, NH4+//Cl--H2O, the region of CaCl2 center dot 6H(2)O crystallization is smaller than that of NH4Cl. Salt CaCl2 center dot 6H(2)O has a salting out effect on NH4Cl. In the stable phase diagram of Sr2+, NH4+//Cl--H2O, the crystallization region of SrCl2 center dot 6H(2)O is smaller than that of NH4Cl, and salt SrCl2 has salting out effect on NH4Cl.