Mass spectrometric determination of the thermodynamic properties of the vapour species from alumina

Abstract

The vapour species over Al₂O₃(c) were determined mass spectrometrically from an alumina effusion cell. These data are in good agreement with previously published weight loss data since the partial pressures of the suboxides, AlO, Al₂O, AlO₂ and Al₂O₂ were found to be of the same order as those of the elements, Al and O. New values were determined for the ΔH_f298K of AlO, Al₂O, AlO₂ and Al₂O₂ of 17.0 ± 2.0, –33.2 ± 3.0, –44.3 ± 2.0 and –113.6 ± 2.0 kcal/mol, respectively. Excellent agreement was obtained between second and third law studies.