E.M.F. cell set-up and thermodynamic investigation of liquid Pb-Bi alloys at 550 and 575 °C

Activities of lead in lead-bismuth alloys at 550 and 575 °C are measured at various compositions i. e. at XPb = 0.1, 0.3, 0.5, 0.7 and 0.9 wt.% in galvanic cells of the type, Pb|LiCl+KCl+PbCl2|(Pb+Bi). Activity and activity coefficients of lead and bismuth, partial molar and excess partial molar free energies of lead and bismuth are calculated and tabulated at XPb = 0.1 to 0.9. By taking calorimetric ΔH values, ΔS and ΔSex values are calculated and tabulated. All these thermodynamic functions are internally consistent and also consistent with other published data. The variation of ΔSex with composition, suggests that in the liquid alloy segregation occurs at about XPb = 0.45 and association at about XPb = 0.65.