Thermochemical properties of gaseous Li3O and Li2O2

Besides LiO and Li2O, the gaseous species Li2O2 and Li3O were observed by mass spectrometric measurements over solid lithium oxide. From the measurements of the gaseous equilibria Li2O(g)+Li2(g) ?Li3O(g)+Li(g), 2 Li2O(g) ?Li3O(g)+ LiO(g), Li2O2(g)+Li2(g) ? 2 Li2O(g) and Li2O2(g)+ Li2(g) ?Li3O(g)+LiO(g), the atomization energies d°0(Li3O) =229.0±10 kcal/mol and D°0(Li2O2) 293.0±12 kcal/mol were obtained. The ionization potentials were determined as I.P.(Li3O) =4.54±0.2 eV and I.P.(Li2O2) =7.88±0.2 eV, from which the binding energies D°0(Li3O+) =438.0±15 kcal/mol and D°0(Li2O2+) =425.0±16 kcal/mol result. The heats of formation were determined as: ΔH°0(Li3O) =−(54.5±10) kcal/mol and ΔH°0(Li2O2) =−(98.0±12) kcal/mol.