Dissociation Energy of NaO(g) and the Heat of Atomization of Na2O(g)

Publisher Website
Google Scholar
Abstract
The vaporization of Na2O(c) has been studied mass spectrometrically. It was found that the vaporization yields primarily Na(g) and O2(g), with NaO(g) and Na2O(g) being minor vapor constituents. From equilibria involving Na2O(c), Na2O(g), Na(g), NaO(g), and O2(g), it was possible to measure ΔHf298°[NaO(g)] = 24.3 ± 4 kcal/mol and ΔHf298°[Na2O(g)] = − 9.9 ± 3 kcal/mol. These values yield D0°(NaO) = 60.3 ± 4 kcal/mole (2.61 ± 0.20 eV) and D0°(Na2O) = 119.8 ± 3 kcal/mol (5.20 ± 0.15 eV). The appearance potentials of NaO+ and Na2O+ were measured and found to be 6.5 ± 0.7 and 5.5 ± 0.5 eV, respectively. These appearance potentials are suggested to be close to the true ionization potentials of the molecules. Implications of these results regarding some recent beam experiments are briefly discussed.