Compositions, Densities, Conductivities, and Refractive Indices of Potassium Chloride or/and Sodium Chloride + PEG 4000 + Water at 298.15 and Liquid−Liquid Equilibrium of Potassium Chloride or Sodium Chloride + PEG 4000 + Water at 333.15 K

Phase diagrams have been measured for the ternary systems KCl + PEG + H 2 O and NaCl + PEG + H 2 O at 298.15 K and 313.15 K and for the quaternary system NaCl + KCl + PEG + H 2 O at 298.15 K. In all the cases PEG of molecular weight 4000 has been used. Density, refractive index and electrical conductivity were also determined for all the saturated solutions at 298.15 K. Equations are proposed in order to correlate the equilibrium and physical properties data of the ternary systems at 298.15 K. At 298.15 K, the PEG addition decreases the solubility of all the experimental systems and only one liquid phase in equilibrium with solid phase is found. In the quaternary system, the presence of two salts decreases the individual salt solubility values, being this effect more important for KCl. At 333.15 K, both ternary systems contain a region with two liquid phases in equilibrium, where a liquid is rich in salt and the other one in PEG. The liquid−liquid-solid equilibrium was determined for both systems. The field of crystallization of the corresponding salt is bigger at 298.15 than to 333.15 K. Similar behavior for both salts, KCl and NaCl was found.