Thermodynamic properties of the calcium + calcium chloride system measured by an electrochemical technique

Abstract

A galvanic cell study of the Ca + CaCl₂ system is reported. By proper allowance for electronic conduction in the electrolyte phase, the thermodynamic properties have been determined. These data are in good agreement with a vapour pressure study and phase diagram determinations. A model is proposed based upon non-stoichiometric compound theory involving an electron pair exchange equilibrium (Ca₂)²⁺⇌ 2Ca²⁺+ e₂ at low Ca concentration. As the Ca concentration approaches saturation, electron pairs are increasingly dissociated and the solution may be described by the equilibrium (Ca₂)²⁺⇌ 2Ca²⁺+ 2e.