Binary mixtures freezing point depression

Data reduction of cryoscopic measurements is made by applying the relation for the freezing point depression of a binary mixture to obtain solvent activities ... 

The increase of the liquid range of binary mixtures based on a polar (e.g., EC) and a nonpolar component (e.g., DMC) by salt addition refiects the association of the electrolyte. Large freezing point depressions are obtained in EC-rich mixtures, whereas DMC-rich mixtures yield only small depressions. As a consequence the minimum of the eutectic phase diagrams shifts to higher EC contents. For example, EC/DMC-mixtures show an eutectic point at a molar ratio of EC x c = 0.348 at —7.76°C. The temperature minimum of the ternary mixture EC/DMC/LiPFg is obtained at —16.04°C and %ec = 0.476 [55]. 

This curve will, of course, lie in the plane formed by one face of the prism. In a similar manner we obtain the freezing-point curves Ak C and B gC. These curves give the composition of the binary liquid phases in equilibrium with one of the pure components, or, at the eutectic points, with a mixture of two solid components. If to the system represented say by the point ki, a small quantity of the third component, C, is added, the temperature at which the two solid phases A and B can exist in equilibrium with the liquid phase is lowered and this depression of the eutectic point is all the greater the larger the addition of C. In this way we obtain the curve which slopes inwards and downwards, and indicates the varying composition of the ternary liquid phase with which a mixture of solid A and B are in equilibrium. Similarly, the curves fegK and k K are the corresponding eutectic curves for A and C, and B and C in equilibrkim with ternary solutions. At the point K, the three solid components... 

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