Phase tree, forecast of crystallizing phases and description of chemical interaction in the system KCl–CaCl2–BaCl2

Abstract

The construction of a phases tree of a ternary system with three binary compounds KCaCl3, K2BaCl4, CaBaCl4 is given. The phase tree includes four secondary phase triangles CaCl2–KCaCl3–СаBaCl4, CaBaCl4–KCaCl3–BaCl2, KCaCl3–BaCl2–K2BaCl4 and KCaCl3–CaBaCl4–KCl. These triangles are connected by three stable secants KCaCl3–СаBaCl4, KCaCl3–BaCl2, KCaCl3–K2BaCl4. Crystallizing phases in stable and secant elements correspond to the simplex tops. The presence of binary compounds on adjacent sides of the composition triangle made it possible to reveal, in addition to addition reactions, the reactions of mutual exchange. The description of the main reactions for mixtures corresponding to the intersection points of unstable and stable secants is carried out. The possibility of these reactions has been confirmed by thermodynamic calculation of thermal effects and Gibbs energies for standard conditions. Using the constructed tree of phases for any mixtures in a triangle of compositions, including 2...6 salts, a description of the chemical interaction by the ion balance method is carried out. The ion balance method allows you to determine the final composition after reaction in a secant or stable element. Complex gross-reactions are presented as a set of simpler reaction equations. The proposed method for description the chemical interaction can be used for other types of ternary systems with exchange reactions (metathesis) – with ion-exchange processes and with displacement reactions.