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The Journal of Physical Chemisfry, Vol. 83, No. 22, 7979
K.
(6) The small term (0.04f 0.16)(DN/kJ mot‘) has been neglected inside the square brackets. Similarly negligible dependencies on the donor properties of the solvents were obtalned also for azide, tetraphenyiborate, and thiocyanate anlons, besides chloride. Only for bromide and i d i e are the coefficients of (DN/W mol-‘) comparable with the standard error: 0.13 0.17and -0.17f 0.08,respectively. (The original definitions of E , and DN are in terms of kcai mol-’; 1 cal = 4.184 J.) (7) A. J. Parker, Chem. Rev., 69, 1 (1969);A. J. Parker, V. Gutmann, and U. Mayer, J . Org. Chem., 43, 1843 (1978). (8) Y. Marcus, E. Pross, and J. Hormadaly, to be published. (9) Y. Marcus and L. E. Asher, J. Phys. Chem., 62, 1246 (1978). (10) Z.Rappoport and J. Kaspi, J. Am. Chem. So., 96,4518 (1974).
*
H. Stern, M. L. Deanhardt, and Rm. Panayappan
(1 1) C. Reichardt, “Solvent Effects in Organic Chemlstty”, Verlag Chemie, Weinheim, 1979. (12)For recent discussions see L. B. Kier, L. H. Hail, W. J. Murray, and M. Randic, J. Pharm. Scl., 64, 1971 (1975);G. L. Amidon and S. T. Anik, lbld., 65, 801 (1976). (13) T. B. MacMahon and P. Kebarie, J. Am. Chem. SOC.,99,2222 (1977);R. T. McIver and J. H. Silvers, Ibld., 95, 8462 (1973). (14)J. B. Cumming and P. Kebarle, J. Am. Chem. Soc.,99, 6999 (1977); P. Schuster, W. Jakubetr, and W. Marins, Top. Current Chem., 60,
l(1975). (15) R. P. Taylor and I. D. Kuntz, J . Phys. Chem., 74,4573 (1970);J . Am. Chem. SOC.,94,7963 (1972);T. Kenjo, S. Brown, E. Held, and R. M. Diamond, J. Phys. Chem., 76, 1775 (1972).
Studles of the Na20-Na2SO4 System Kurt H. Stern,* M. L. Deanhardt,+and Rm. Panayappan Chemistry Division, Naval Research Laboratory, Washington, D.C. 20375 (Received February 1, 1979) Publication costs assisted by the Naval Research Laboratory
The behavior of Na20-Na2S04melts at 920 “Chas been studied by four techniques; (1)chemical analysis of quenched melts, (2) manometric experiments in which the reversible uptake of O2by the melts was observed, (3) potentiometric studies, using oxide ion specific zirconia electrodes, and (4)voltammetry, which detects the number of oxidizable species. In oxygen atmospheres all four studies are consistent with peroxide formation in the melt, although values of the peroxide/oxide ratio vary somewhat with method. At low O2pressures (
