ELEC'TROMOTIVE FORCE RIEASUREMEXTS IN THE SYSTEM AgSO,-NaClSaXO:i h S D THEIR COMPARISOK I'I'ITH THE QUASI-LATTICE THEORY BY D. G. HILL,'J. BRACNSTEIX~ .4XD AI. BLANDER Oak Ridge LVational Laboratory, 1'. 0 . Box I', Oak Ridge, Tennessee3 Remi ed Febr uari, 26'. 10170
XIcasuremcnts of the activity corfficients of Agn'Oi, -,Ag\i08, in dilute solutions of Ag+ and Cl- ions in N:iSO, have tiern made a t 331, 364, 385, 402, $23, 438 and 500". The concentration dependence of log yLgxoj is closer to the s y m n i e t r i c approximation based on the quasi-lattice model than to the asymmetric approximation. Average values of the rrlative energies of ion pair formation, AE, as defined in the gitns&ttice model, were calculated by comparison of the symmetric approximation with the experimental results. For Z = 4, 5, and 6 the values of AE averaged over all seven temperatures are -5.13, -4.83 and -4.59 kcal./mole, respectively. The values of AE n w e constant, within experimental precision, a t all seven temperatures. The conventional association constant for the formation of the ion pair A--C-, K,, is q n a l to Z[e\p( - L E / R T ) - 1 I . The constancy of AE a t all temperatures studied and for 311 reasonable values of Z means that from measurements of K1 a t one trmperature, one may, in this system, correctly predict K , a t all other temperatures by use of the lattice model.
Introduction SIeawrements of the activity coefficients of -IgSO? in dilute solutions of -Zg+ and CI- ions in molten Sa?S07 at several temperatures ranging from 331 to 300" arc described in this paper. These measurements are part of a continuing study :it this Laboratory of the thermodpiiamic properties of molten reciprocal salt systems. In prex-ious papers45 measurements in the system LIgSO1- IiC1-I
