Study of chemical and electrochemical properties of some elements in molten NaAlCl

We describe a study of the electrochemical and chemical properties in molten mixtures of Aluminium Chloride-Sodium chloride, at 210 deg. C and the concept of acidity, related to chloride activity, is previously summarized. In a first part, the study of Mercury and Cadmium by means of electro-analytical techniques, states the Hg2+2, Hg2+, Cd2+2 and Cd2+ ions and their acid properties. Some diagrams Equilibrium potential vs acidity are the synthesis of these results. In a second part, it is shown that a nickel electrode is an indicator of the presence of oxide ions; from interpretation of electrochemical results, O2 appears to behave, in terms of the chloro-acido-basicity concept, as a strong di-base, giving the solvated form AlOCl-2, or a strong tri-base giving AlOCl. A saturation effect by Al2O3 appears when the oxide concentration is increased; the solubility of Al2O3 versus acidity is determined from the electrochemical results. In a third part, results for the Ni/Ni(II) or HCl/H2O systems are related to dissolved oxide ion presence in chloroaluminate melts; elimination of oxide ions, through H2O formation, by reaction with HCl is noteworthy. (author)