Uber die Thermodynamik der Verdampfung von Scandium(III)-fluorid

On the thermodynamics of vapourization of scandium(III) fluoride The vapourization behaviour of solid ScF₃ was studied by the KNUDSEN effusion method. ScF₃ vapourizes congruently with practically stoichiometric composition in a high vacuum at temperatures from 1300 to 1600°K. Within the temperature ranges 1336–1400K and 1440–1528°K the vapourization was found to obey the equations respectively, assuming monomeric ScF3 to be the predominant gaseous species. By considering literature data for the vapourisation behaviour of AlF₃(s) and LaF3(s) the content of SC₂F₆ (g) in the saturated vapour over SeF₃ (s) was estimated to be approximately 0.3% at 1368 ° K. Second an Third Law calculations were performed using known and estimated thermodynamic data for ScF₃(g) and ScF₃(s), respectively, and the enthalpies and the enthalpies and entropies of vapourization at 298.15 ° K were obtained (data see “Inhaltsübersicht”). A. critical discussion of the experimental and theoretical results allowed to conclude that vapour pressures of ScF₃(s), which were determined by others within were found to be three to four orders of magnitude higher than the vapour pressures determined in this work where are are less probable.