Calorimetric investigation of Pb–Bi system

The enthalpy of formation of ɛ-compound, Pb0.68Bi0.32, was determined at 448 K by successive precipitation method. The enthalpy of formation of ɛ-compound, Pb0.71Bi0.29, was determined by tin and lead solution calorimetry. By successive precipitation method, the ΔHf° of Pb0.68Bi0.32 from Pb(l) and Bi(l), at 448 K, was −3.85 ± 0.05 kJ/mol. From this value, the enthalpy of formation of the compound from Pb(s) and Bi(s) at 298.15 K was calculated as 2.7 ± 0.15 kJ/mol. The enthalpy of formation of Pb0.71Bi0.29 at 298.15 K, by tin solution calorimetry was 2.7 ± 0.15 kJ/mol and by lead solution calorimetry was 2.75 ± 0.15 kJ/mol.