The objective of the course is to familiarise the participants with the present methods of thermodynamics of mixed phases and their fields and limits of application. Special focal points will be on such aspects, that are - by our opinion - of major importance for the successful modelling of single separation apparatus or complete units. This includes the thermodynamic data of pure substances and, especially, the characteristics of phase equilibrium of mixtures as well as the analysis of the behaviour of multi-component systems. Besides the common models we will present also points of departure for the description of real behaviour of mixtures contending electrolytes. After a profound treatment of the necessary thermodynamic fundamentals as well as fundamentals for the design of several unit operations (e.g. rectification, crystallisation, membrane techniques), we will go into detail with the solution of problems of process engineering by means of up-to-date thermodynamic approaches. This includes e.g. a selection of additives for special techniques (azeotropic as well as extractive rectification, extractive as well as adductive crystallisation, hybrid techniques, two-pressure techniques, etc.) and a profound discussion of the possibilities and limits of rectification. The ability and understanding of different graphic presentations of mixture characteristics (presentation on a solvent-free basis, iso-graphs, distillation graphs, etc.) will be intensively trained. Periodical exercises (in part with the program MathCAD) help to consolidate the subject matter and offer the possibility to the participants to improve their understanding by solving open problems. An introduction into the procedures and operating of the process simulator Aspen Plus (version 10.0) will be given in the last day. This part is especially made up for students which did not yet have a possibility to work with a process simulator.