Calorimetric investigation of the solid compounds of the Au-Pb system

The three intermediate compounds of the Au-Pb system were synthesised by me lting the pure components in suitable proportions and annealing at a temper ature just below their melting point. Their structural stares were verified by X-ray studies. The enthalpy of formation of the compounds was measured by dissolution calo rimetry (drop method) at 650K in liquid lead using a high temperature Tian- Calvet calorimeter. The measurements lead to: h(f)(Au0.667Pb0.333, cr, 298 K) = - 3.1 kJ mol(-1) h(f)(Au0.333Pb0.667, cr, 298 K) = - 3.2 kJ mol(-1) h(f)(Au0.25Pb0.75, cr, 298 K) = - 1.6 kJ mol(-1) (C) 1999 Elsevier Science S.A. All rights reserved.