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

Phase Diagram of the Reciprocal System 2NH⁺₄, Mg²⁺//SO^2-₄, 2NO^-₃–H₂O

P. Fellner and V. Khandl

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

E-mail: pavel.fellner@stuba.sk

Received: 16 January 2003

Abstract: Phase equilibria in the reciprocal system 2NH⁺₄ ,Mg²⁺//SO²⁻₄ ,2NO⁻₃ —H₂O were investigated in the temperature range of 70°C—115°C. It was found out that two double salts can exist in this system, viz. (NH₄)₂Mg(SO₄)₂ · 6H₂O (boussingaultite) and (NH₄)₂Mg₂(SO₄)₃ (efremovite). Boussingaultite is stable up to (107 ± 3)°C while at higher temperatures efremovite crystallizes from aqueous solutions. Boussingaultite loses its hydrate water when heated to the temperatures higher than 110°C. However, its transformation to efremovite is very slow. Detailed phase diagram of the system 2NH⁺₄ ,Mg²⁺//SO²⁻₄ ,2NO⁻₃ —H₂O at the temperature of 90°C is presented.

Full paper in Portable Document Format: 584a221.pdf

Chemical Papers 58 (4) 221–223 (2004)