ENTHALPIES OF FORMATION OF CENI2 AND CENI5 BY CALORIMETRY

The enthalpies of formation of the intermetallic compounds, CeNi2, and CeNi5 at 298.15 K have been determined by high temperature solution c alorimetry. The thermal effects of dissolution of nickel, cerium and t he intermetallic compounds in liquid aluminum at 1095.15 K were determ ined as a function of concentration of the solutes from which the resp ective thermal effects of dissolution at infinite dilution were derive d. The enthalpies of formation of the compounds at 298.15 K were compu ted from these values of thermal effects of dissolution at infinite di lution. The enthalpies of formation of CeNi2 and CeNi5 at 298.15 K thu s obtained are -115.8 +/- 7.3 and -201.9 +/- 11.9 kJ mol(-1), respecti vely. The present enthalpy of formation of CeNi5 is compared with the earlier literature values. In the case of CeNi2 the study provides the only experimental data for the enthalpy of formation. (C) 1997 Elsevi er Science B.V.