Thermochemical Properties Over LiCl-KCl-UCl3 Ternary Salt System: Knudsen Effusion Mass Spectrometric Study

Abstract

Vaporisation studies were carried out over the solid region of LiCl(cr), KCl(cr) and liquid region of LiCl-KCl-UCl₃ ternary salt system by using Knudsen Effusion Mass Spectrometry (KEMS) in the temperature range of 715–913 K. Monomeric and dimeric species were observed in the vapour phase in equilibrium with their respective salts, LiCl(cr) and KCl(cr). LiCl(g), Li₂Cl₂(g), KCl(g), K₂Cl₂(g), and UCl₃(g) were the neutral species observed in the equilibrium vapour over ternary salt. Partial pressure–temperature relations for vapour species were derived using in-situ calibration from pressure dependent equilibrium constants as well as using pure silver as external calibrant. Using p-T relations, various heterogeneous reaction equilibria that exist between condensed phase-gas phase and the dissociation equilibra of following gas phase reactions: Li₂Cl₂(g) = 2LiCl(g); K₂Cl₂(g) = 2KCl(g) were evaluated by using 2nd and 3rd law methods. Also, the enthalpies of pressure-independent reactions: LiCl(cr) + LiCl(g) = Li₂Cl₂(g); KCl(cr) + KCl(g) = K₂Cl₂(g) were evaluated by using 3rd law method. Knudsen effusion mass spectrometric studies on LiCl-KCl-UCl₃ ternary salt system were carried out for the first time.