Solubility Relations in Ternary Solid Solutions of Ionic Compounds

Abstract

The variation of the solubility of a solute due to the presence of a second solute in a solid ionic compound as solvent is investigated theoretically with the aid of the ideal law of mass action. Ions of the solvent in interstitial positions, cation and anion vacancies, quasi‐free electrons, and electron holes are to be taken into account in the same manner as the constituents of conventional chemical systems. The theoretical conclusions are illustrated by experimental data, however, qualitatively rather than quantitatively. The solubility of lead chloride in solid silver chloride is decreased by presence of cadmium chloride. The solubility of iodine (or cupric iodide) in cuprous iodide is likewise decreased by presence of cadmium iodide. The behavior of the corresponding bromide system is analogous. Conversely, gallium oxide increases the solubility of zinc in zinc oxide. The phenomena to be expected in lead sulfide as solvent are more complicated, since this substance can dissolve both excessive lead and excessive sulfur. The oxidation rate of nickel is increased by presence of chromium and manganese, whereas the chlorination rate of silver is decreased by presence of lead and cadmium chloride.