J. D. van der Waals
J. D. van der Waals was a Dutch scientist from Leiden, who developed in his doctoral thesis in 1873 the first equation of state p(V,T) that could model the liquid phase, phase equilibria of fluids and the critical point. He took into account the covolume of the molecules and hence their repulsion as well as their attractive interaction. By means of mixing rules, in which the parameters are parameters are averaged in a suitable way, it was also possible to calculate phase equilibria of binary mixtures could be calculated. Equations of state for real fluids are today the basis for modeling countless technical processes, such as distillation, extraction, particle production, etc.