Hydration and association equilibria in molten salt solutions containing water. I. The association of cadmium ion with bromide in the solvent lithium nitrate-potassium nitrate-water

Vapor pressures o aqueous melts. Lithium nitrate-potassium nitrate-water at 119-150.deg.

“…More recently, the model was extended to take into account the differences of the relative binding energies of water molecules and halide ions to the cations.12 This model was shown to give excellent agreement for the association equilibria of Cd2+ with Brin the solvent H20equimolar LÍNO3-KNO3 at water contents between the anhydrous molten salt and 50 mol % water at 119-171°. 13 The system LiNO3-KN03-H20 is convenient for experimental studies of electrolytic solution properties because of the wide range of temperatures and wrater contents accessible to measurement. The volumetric properties of these mixtures have been reported…”

Solvation of Ions

“…Electromotive force studies on the proper galvanic cells showed that in molten salt solutions containing water, the water molecules could be considered as ligands competing with bromide ions for the displacement of nitrate ions from the coordination spheres of cadmium ions [148]. It was also observed that bromide ions displace nitrate ions from the coordination sphere of cadmium ions more readily than they displace water molecules since the association constant for the reaction Cd 2 + +Br~ -+ CdBr + increased with decreasing water content.…”

Hydration and association equilibria in molten salt solutions containing water. II. A quasi-lattice model

“…To obtain the most probable distribution of the "ligands" C and H between sites adjacent to A and sites not adjacent to A, the logarithm of the combinatorial factor is maximized subject to the constraint of eq 3 on the energy of the "lattice." 19 The association constant for CdBr+ in anhydrous LiS03-Kn'03 has been of AC is 11, 16,17919 (The values of K1 calculated a t different water contents from eq 10 will differ in general since the ligand C may displace either a solvent anion D or a ligand H.) Differentiation of eq 9 gives the corresponding equation obtained from the model These anion sites will be occupied by NkT -E Gc - The combinatorial factor for the anion sublattice is A (e.g., cadmium ion), the cell follows the Nernst equation in the concentration of BC (e.g., halide) a t a fixed concentration of water.…”

“…The model is applied to association constants which have been reported for CdBr+ in anhydrous equimolar lithium nitrate-potassium nitrate and in aqueous melts containing up to 56 mole % of water. 19 Since, however, the model is essentially a description of mixed ligand association, it should be applicable also to the effects of dissolved polar gases other than water, or of other anionic ligands, on association constants in solution.…”

“…Equation 12predicts a linear dependence of the reciprocal of the association constant on the mole ratio of water at constant temperature and may be applied to the data reported previously. 19 The terms a and ß are temperature dependent.…”