Theoretische Behandlung flüssiger Mischungen mit Hilfe von Gleichgewichtsmodellen. Teil II. Binäre symmetrische Mischungen (Mischungsenthalpien, Dampfdrude- und Siedediagramme, Azeotropie, flüssig-flüssig-Entmischung)
Theoretical Treatment of Liquid Mixtures by Means of Equilibrium Models
- This paper contains further applications on symmetrical liquid mixtures of the molecular thermodynamic theory which has been developped in part I of this series. The essential feature of this theory is the superposition of "chemical" and “random” exchange equilibria between “complexes” formed by a given molecule and its z nearest neighbours, thus allowing a unified treatment of the thermodynamic phenomena in binary liquid mixtures using the equilibrium constant K of the ideal law of mass action and the energy w of pair interactions as parameters.
The temperature and pressure dependences of K and the evaluation of experimental excess enthalpy and excess volume data are treated. Formulas and examples for the calculation of K and w from isothermal and non-isothermal vapour-liquid equilibrium data are given. The conditions for azeotropy with minimum or maximum vapour pressure, resp., are derived. Melting curves for a symmetric eutectic system with superposed miscibility gap are discussed. Further models for partially miscible liquids with competing self-association and complex-formation are treated showing the phenomenon of two separated miscibility gaps.