Solubility of Silver in Liquid Cesium and Thermodynamic Properties of the Solutions

The solubility of silver depending on temperature in individual potassium and cesium and with additives of their halides to these alkali metals has been determined for several years at the Institute of High-Temperature Electrochemistry (Ural Branch, Russian Academy of Sciences). At the beginning of the research, the studies are assumed to be corrosive due to the prevailing opinion in the literature about a low solubility of silver in potassium and a lower solubility in cesium. The solubility of silver in cesium is shown to be higher than that in potassium. The measurements of the solubility of silver in liquid cesium at temperatures from 500 to 900 degrees C are presented. The average solubility for each temperature varies from 0.94 to 11.1 mol % Ag, respectively. The experimental data on the solubility of silver in cesium are approximated by a quadratic polynomial N-Ag = 6.066 x 10(-5)T (2) - 5.966 x 10(-2)T + 15.58, where N-Ag is the solubility of silver (mol %) and T is temperature (degrees C). The activity coefficients of silver, partial enthalpy of mixing of silver, and its partial excess entropy in these solutions are calculated using the data on the solubility of silver in cesium and the Schroeder equation of ideal solubility. The partial enthalpy of mixing of silver and its partial excess entropy are Delta H-Ag = 38 154.8 J/mol and Delta S-exAg = 14.215 J mol(-1) K-1, respectively. The Schroeder equation is used under the assumption that the enthalpy of silver melting is temperature independent. The logarithms of the activity coefficient of silver versus temperature are approximated by the equation ln(y(Ag)) = 4589 x 1/T - 1.7097. The approximation inaccuracy is R-2 = 0.9818.