ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Two Approaches to the Calculation of the Phase Diagrams Containing Congruently Melting Compounds Systems NaF—Na₂SO₄ and NaF—NaAlF₄

V. Danielik, J. Gabčová, and P. Fellner

Department of Inorganic Technology, Faculty of Chemical Technology, Slovak University of Technology, SK-812 37 Bratislava

Abstract: Phase diagrams of the systems NaF-Na₂SO₄ and NaF-NaAlF₄ (the systems containing compounds Na₃FSO₄ and/or Na₃AlF₆) were calculated using two different assumptions: i) The congruently melting compound (Na₃FSO₄ or Na₃AlF₆) completely dissociates. ii) The compound dissociates only partially. It is shown that both models are formal and as far as solidus-liquidus equilibria are concerned they yield approximately the same results. The model based on partial dissociation of the complex compound assuming the ideal behaviour of liquid phase is improper for description of the thermodynamic behaviour of the system.

Full paper in Portable Document Format: 534a233.pdf

Chemical Papers 53 (4) 233–237 (1999)