Experimental and Modelling of liquid –solid equilibria

Solid-liquid equilibria are less considered in inorganic thermochemistry, comparatively to the other two types of phase equilibria involving vapour and/or liquid phases. The great majority of the relevant models, particularly for the calculation of the activity coefficient, concern these last two cases, although their use is extended to handle the solid-liquid equilibria. The first part of the present work concerns an experimental study for the determination of the liquid –solid phase equilibrium diagrams, for various binary systems such as salicylic acid in water, ethanol and chloroform, and naphthalene in phenol, by the means of Differential Scanning Calorimetry. The second part consists of a modeling of these phase equilibria by means of various thermodynamic models such as NRTL, UNIFAC which are also tested for binary systems such as naphthalene in organic solvents. The use of these models requires interaction parameter values which are not always available. Therefore, this work was an opportunity to compute these parameters for the different systems considered. The results obtained experimentally and by modeling, concerning the phase diagrams showed a good agreement, particularly for the NRTL model, compared to UNIFAC which is based on the concept of group contribution and thus is approximate