Study of the solubility, viscosity and density in Na+, Zn2+/Cl− − H2O, Na+ − Zn2+ − (H2PO2)− − H2O, Na+, Cl−/(H2PO2)− − H2O, and Zn2+, Cl−/(H2PO2)− − H2O ternary systems, and in Na+, Zn2+/Cl−, (H2PO2)−//H2O reciprocal quaternary system at 273.15 K

Highlights: • The physicochemical properties of ternary and one quaternary have been studied. • Reciprocal quaternary systems' solubility and phase equilibrium have been studied. • In all systems the solid phases have been found. • It was found that Zn(H2PO2)2 salt contains 70% of the general crystallization field. - Abstract: The solubility and the physicochemical properties (density, viscosity) in the Na-Zn- Cl-H2O), (Na + Zn + H2PO2 + H2O), (Na + Cl + H2PO2 + H2O), and (Zn + Cl + H2PO2 + H2O) ternaries, and in Na+, Zn2+/Cl−, (H2PO2)−//H2O reciprocal quaternary systems at T = 273.15 K were investigated by using the isothermal method. The diagrams of ternary salts systems, (NaCl + ZnCl2 + H2O), (NaCl + NaH2PO2 + H2O), (NaH2PO2 + Zn(H2PO2)2 + H2O), (ZnCl2 + Zn(H2PO2)2 + H2O), are plotted in figures 1–4. However, whole ions of reciprocal quaternary salt systems are plotted in figure 5. Additionally, the density and viscosity values of ternary systems vs. their corresponding composition values in weight per cent are plotted in figures 6–10. At the (i) (ZnCl2 + Zn(H2PO2)2 + H2O), (ii) (NaCl + ZnCl2 + H2O), (iii) (NaCl + NaH2PO2 + H2O), (iv) (NaH2PO2 + Zn(H2PO2)2 + H2O) ternary systems the solid phase compositions have been determined as: (i) Zn(H2PO2)2 ⋅ H2O, Zn(H2PO2)2, ZnCl2 ⋅ 2H2O, (ii) NaCl, 2NaCl ⋅ ZnCl2 ⋅ 2H2O, and ZnCl2 ⋅ 2H2O, (iii) NaCl and NaH2PO2 ⋅ H2O, (iv) Zn(H2PO2)2 ⋅ H2O and NaH2PO2 ⋅ H2O, respectively. On the other hand reciprocal quaternary system was observed as: ZnCl2 ⋅ 2H2O, 2NaCl ⋅ ZnCl2 ⋅ 2H2O, Zn(H2PO2)2 ⋅ H2O, NaH2PO2 ⋅ H2O, NaCl. According to results, the least soluble salt was Zn(H2PO2)2. The crystallization field of this salt, being the largest in comparison with those of other salts, occupied 70% of the general crystallization field