Thermodynamic properties of some molten salt mixtures form E.M.F. measurements

Electromotive force measurements have been completed on formation cells of the type: `A(1)``/AX_2``(1)` + `MX(1)``/C,` `X_2``(g)` where `AX_2` is a molten divalent metal halide and `MX` a molten alkali metal halide. The following systems have been investigated: binary; `PbBr_2``-MBr` `(M = K, Rb, Cs)`, `PbCl_2``-CsCl` ternary; `PbCl_2``-CsCl``-MCl` `(M = Li, Na, K, Rb)` reciprocal; `CdX_2``-NaY` `(X = Br or Cl, Y = Cl or Br)` The thermodynamic properties of the components have been discussed in terms of complex ion formation, association of the standard state (the pure divalent metal halide, `AX_2`) and the influence of the alkali metal ion, `M^+`, on the stability of the complex ions. Activity models have been postulated to explain the deviations of the activity of `AX_2` from the ideal Temkin activity.