Salt Effect in Metal-Ammonia Solutions: Sodium Chloride in Sodium-Ammonia Solution at —33°C

Using the model of Becker, Lindquist, and Alder for the equilibria in a solution of sodium in liquid ammonia, the authors have assumed an additional equilibrium between sodium and chloride ions and dissociated sodium chloride to compute the concentrations of ionic species, atoms and dimers when the common-ion electrolyte sodium chloride is added. Estimates of the ionic activity coefficients are included in the calculation. The calculated concentrations of conducting species are employed in the Onsager-Kim theory for the conductance at low fields of a mixture of ions. Values of [Na]total ranging from 5×10—4 to 6×10—2 and of the ratio of sodium chloride to [Na]total ranging from zero to 28.5 are included in the calculations. All data are for —33°. The computed conductances are compared with some newly-reported experimental measurements. The calculations are described and the results analyzed and criticized in light of values of the equilibrium constants for the sodium-ammonia system available from a variety of measurements.