Volumetric properties and electrolytic conductances of aqueous ternary mixtures of hydrogen chloride and some transition metal chlorides at 25°C

Densities and electrolytic conductances of hydrochloric acid and ternary aqueous solutions of HCl with manganese(II), copper(II), and cadmium(II) chlorides, respectively, have been measured from about 0.2 m to ternary saturation points at several constant molalities of the salt, MnCl₂, or that of HCl for the system MnCl₂–HCl–H₂O as well as at constant total molal ionic strength of I=10.0 for all the three ternary systems (Mn, Cu, Cd)Cl₂–HCl–H₂O at 25°C. The molality dependence of the calculated volume of mixing changes V_m and of the specific conductances are discussed on the basis of the different degrees of complex formation of the bivalent transition metal chlorides in the presence of excess amounts of chloride anions in the form of HCl. It was to be seen from the present results that even the manganese(II) chloride, which behaves as a fairly strong electrolyte in dilute aqueous solutions, is considerably complexed at high concentrations of HCl, with the degree of complexation of the cations increasing in the sequence Mn^2–2–2–.Part of this publication was presented at the XIX International Conference on Solution Chemistry (XIX ICSC), Lund, Sweden, August 15–18, 1988.