MgCl2 -alkali chlorides

The data published in the literature suggest that MgCl2 does not exist as Mg2+ cations and Cl" anions when dissolved in alkali chloride melts. These solvents act as ligand donors, and magnesium is found as anionic complexes in the melt. 

On the basis of emf data, obtained for the system MgCl2-KCl at 800°C, the equilibrium constant of reaction (109) was calculated to be 1.8 10 3. Such a low value of the dissociation constant is an indication of the high stability of the MgCl42 ion. The conclusion which results from these thermodynamic studies is that there are complex species present in melts of alkali chlorides containing magnesium chloride. 

One step in the pyrochemical processing of Pu (9.2.2.1) is molten-salt extraction of Am from Pu metal in an alkali chloride-MgCl2 melt. Americium has greater reducing strength than Pu toward MgCl2, and the molten salt extraction exploits this property. ... 

The range of enthalpies of solution of anhydrous lanthanide trichlorides in water may be compared with those for other anhydrous chlorides. They are considerably more negative (Table IV) than those for the alkaline-earth metals [MgCl2, -155 kJ mol-1, to BaCl2, -13 kJ mol-1 (196)] and for the alkali metals [LiCl, — 37 kJ mol-1, to CsCl, +18 kJ mol-1 (197)]. 

C. Why Does the M1Cl-MgCl2-6H20 Double Salt Form by the Addition of a Small Amount of Alkali Metal Ions M1 to a Magnesium(II) Chloride Solution but Not in the Reverse Case ... 

Boghosian et al. (1991) studied the solubility of earth alkali metal oxides in alkali metal-earth alkali metal chlorides and NaCl-MeCl2 melts. They found that the oxide solubility is in general very low and increases markedly with the MeCl2 concentration and with increasing atomic number of the earth alkali metal atom. The very low oxide solubility in earth alkali metal chlorides can be explained by the reaction (e.g. for the MgCl2 melts)... 

The subject of Sect. 5.2.1 to 5.2.4 was the electrochemical production of chlorine and of caustic alkali. It shall be noted in addition, that chlorine is obtained as a by product if metal chlorides like NaCl, MgCl2, or others are electrolyzed in their molten form to produce the metals (see Chapter 4). From aqueous NaCl, caustic alkali and hydrochloric acid can be produced without generation of chlorine, using an electrodialytic separation process [35]. 

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