Stable (solid + liquid) phase equilibrium for the ternary system (NaCl + RbCl + H2O) at T = (288.15, 298.15 and 308.15) K

The (solid   +   liquid) phase equilibrium of the ternary system (NaCl   +   RbCl   +   H 2 O) at T   =   (288.15, 298.15 and 308.15)   K was studied by the method of isothermal solution saturation. Moreover, the density and refractive index of the solution was also determined. The solid phase was studied by the Schreinemaker’s wet residue method and verified by X-ray diffraction. The results show that each of the phase diagrams contains one invariant point, two univariant curves, and three crystallization regions. The crystallization region of NaCl increased obviously with the temperature increasing, while the crystallization regions of RbCl and the mixed crystallization region of (NaCl   +   RbCl) decreased a little. Furthermore, there are break points at the invariant points for density and refractive index curves.