OXOACIDITY REACTIONS IN EQUIMOLAR MOLTEN CACL2-NACL MIXTURE AT 575-DEGREES-C

The behaviour of an yttria-stabilized zirconia electrode in the CaCl2- NaCl melt has been investigated at 575 degrees C. The response of the electrode is Nernstian and permits its use in the titration of Mg(II) with oxide ions. The solubility product of MgO was also determined. We have calculated the equilibrium constant of the carbonate ion dissoci ation as well as those corresponding to the systems HCl/H2O and Cl-2/O -2, finding that molten CaCl2-NaCl is more acidic than the LiCl-KCl eu tectic melt and the BaCl2-CaCl2-NaCl (23.5:24.5:52 mol%) melt. On the other hand, the mixture can be purified with respect to oxide ions by gaseous reagents such as HCl and Cl-2. (C) 1997 Elsevier Science Ltd.