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 PbTeO3 and Pb2TeO4 were calculated by quantum chemistry methods. The formation enthalpies ΔfH0 (298.15) = −294 ± 13 for gaseous PbTeO3 and ΔfH0 (298.15) = −499 ± 12 for gaseous Pb2TeO4 were obtained. On the base of these results the formation enthalpies of gaseous PbPoO3 and Pb2PoO4 were estimated as −249 ± 34 and −478 ± 38, respectively.