Solid-Liquid Equilibria for Nonideal Systems

Following Eq. (8.9) in the case of nonideal systems the knowledge about the real behavior (e.g., activity coefficients yi) both in the liquid and in the solid phase is required as additional information for the calculation of SLE. The deviation from ideal behavior can be taken into account using for example, g -models or equations of state. Starting from Eq. (8.9) for nonideal systems, the following expression is 

From this equation it becomes clear that a temperature maximum occurs when the activity coefficient in the liquid phase is larger than in the solid phase. For a temperature minimum the opposite is true. 

With the assumption that the simple Porter equation 

If the extreme temperature and the composition are known, it is possible to obtain the difference of the Porter parameters A - B. The result of this approach is shown in Example 8.9 for a system with temperature maximum and in Example 8.10 for a system with temperature minimum. 

Calculate the SLE diagram for the binary system D-carvoxime (l)-L-carvoxime (2) with a congruent melting point at a composition x = 0.5, Tmax = 365.15 K using the Porter expression and the following pure component data  

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