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The Discovery of Type-IV Binary Fluid Phase Behavior



Johanna Levelt Sengers


The analysis by Scott and Van Konynenburg of the binary Van der Waals mixture for constant excluded volume uncovered the Type-IV phase diagram as a transition between Type-II and Type-III phase diagrams. The common boundary of the regions of Type-II and Type-III is a locus of tricritical points. The tricritical locus meets the common boundary of regions of Type-II and Type-IV at what Meijer coined the Van Laar point in 1989. As early as 1905, the Dutch chemist Van Laar had studied the geometric-mean Van der Waals binary mixtures, produced Type-II and Type-III phase diagrams, and found the exact coordinates of what we call the Van Laar point, but he did not notice tricriticality explicitly. He postulated and proved the existence of Type-IV. Aspects of his proof are discussed.
Fluid Phase Equilibria


critical state, history, phase diagrams, Van der Waals binary mixture, Van Laar, vapor-liquid equilibria


Levelt Sengers, J. (2008), The Discovery of Type-IV Binary Fluid Phase Behavior, Fluid Phase Equilibria (Accessed May 22, 2024)


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Created October 16, 2008