MASS-SPECTROMETRIC STUDY OF VAPORIZATION OF CESIUM TELLURATE AND TELLURITE

The process of vaporization of cesium tellurate and tellurite was stud ied by the Knudsen effusion method with a mass spectrometric analysis of the vapor composition. The thermal dissociation of Cs2TeO4 to Cs2Te O3 and the congruent vaporization of Cs2TeO3 were established. Thermod ynamic functions for gaseous Cs2TeO3 have been calculated. The standar d enthalpy of sublimation DELTA(s) H-degrees (298.15) = 268.1 +/- 13.0 kJ mol-1 was determined by the 2nd and 3rd laws of thermodynamics. Th e enthalpy of formation DELTA(f) H-degrees (298.15) = -725.1 +/- 13.0 kJ mol-1 for gaseous Cs2TeO3 and the enthalpy of atomization DELTA(at) H-degrees(298.15) = 1841.3 +/- 15.0 kJ mol-1 have been computed.