Calorimetric Determination of the Heats of Formation of Aluminum--Barium Alloys

The heats of formation of some Al--Ba alloys were determined by drop calorimetry at high temperature. The heats of mixing of pure liquid Al and Ba at 1215 deg K to give the liquid alloy are Delta H (XBa = 0.056) = --6.6 kJ/mole and Delta H (XBa = 0.333) = --31.0 kJ/mole. To measure its heat of formation, the solid compound Al4Ba was precipitated by addition of pure Ba from a liquid (Al, Ba) bath. It was found that Delta H (solid, 1215 deg K) = --(37.1 = 1.5) kJ/mole, with reference to the pure metals in the solid state.--Chem. Abs.