Mass spectrometric study of thermodynamic properties of gaseous lead tellurates. Estimation of formation enthalpies of gaseous lead polonates

Abstract Gaseous reactions involving lead oxides, tellurium oxide and lead tellurates were studied by the Knudsen effusion mass spectrometry. Equilibrium constants and reaction enthalpies were evaluated. Structures, molecular parameters and thermodynamic functions of gaseous PbTeO 3 and Pb 2 TeO 4 were calculated by quantum chemistry methods. The formation enthalpies Δ f H 0 (298.15) = −294 ± 13 for gaseous PbTeO 3 and Δ f H 0 (298.15) = −499 ± 12 for gaseous Pb 2 TeO 4 were obtained. On the base of these results the formation enthalpies of gaseous PbPoO 3 and Pb 2 PoO 4 were estimated as −249 ± 34 and −478 ± 38, respectively.