JERRY BRAUNSTEIN
3402
Hydration and Association Equilibria in Molten Salt Solutions Containing Water. 11. A Quasi-Lattice Model1
by Jerry Braunstein2 Department of Chemistry, University of Maine, Orono, Maine
(Received January 27, 1967)
A statistical model of hydration and association equilibria of dilute solute ions in very concentrated aqueous electrolyte solutions is presented. The model assumes competition between ligand anions and water molecules for bonding to a solute cation. To test the equations of the model, values of the parameters of the model are calculated from experimental values of association constants of Cd2+with Br- in the molten salt solvent LiN08KN03and in the solvent LiNO3-I.
RBC- XZRAD RAD RBC RH - ZRAD
RH)]
(9)
The difference [ p ~ c p B C * ] is the quantity which is determined experimentally in the measurements of the emf of c e l l ~ such ~ ~ Jas~ (20) T. L. Hill, “Introduction to Statistical Thermodynamics,” Addison-Wesley Publishing Co., Reading, Mass., 1960.
HYDRATION AND ASSOCIATION EQUILIBRIA IN MOLTEN SALTSOLUTIONS
Ag,AgBr
(Li,K)NO3 (Li,K)NOo H20 AgBr,Ag HzO KBr KBr Cd(N03h
I n applying the model, cadmium ion is represented by A) bromide by " water by HJ and (Li'K)N03 by BD* I n such cells, it has been observed that in the absence of 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. Inspection of eq 8 shows that p g c * , the chemical potential of BC when RAD = 0, is a linear function of the logarithm of RBCwhen RBC
