Calculation of the free energies for the solid phases of ammonium halides

Salihoglu, S.
Yurtseven, Hasan Hamit
Karacali, H.
Using mean field theory, we calculate the free energies of the solid phases of ammonium halides. The temperature and pressure dependences of the free energies are obtained using experimental phase diagrams of the ammonium halides. From these dependences, we calculate numerically the specific heat as a function of temperature for the solid I-liquid, solid II-liquid and solid I-solid II transitions in the ammonium halides, in particular for NH4Cl. The critical behaviour of some other thermodynamic quantities is also predicted from the mean field theory.