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A state of Thermodynamic equilibrium between the liquid and gas state of a Fluid Mixture. 


The 
PT diagram for Pure Substance will see Vapour Liquid Equilibrium (VLE) as a set of points along a smooth curve ending up with a Critical Point  (see Fig. 1).

The PT diagram for Fluid Mixture will see Vapour Liquid Equilibrium (VLE) as a closed area with an apex of Pseudo-Critical Point  (see Fig. 2).



Supercritical carbon dioxide - Wikipedia


Fig. 1. Schematic PT diagram with Vapour Liquid Equilibrium curve and Critical Point.Fig. 2. Schematic PT diagram with Vapour Liquid Equilibrium area and  Pseudo-Critical Point.


See also


Natural Science / Physics / Thermodynamics / Thermodynamic system / Thermodynamic equilibrium 

Pure Substance ]

Сritical Temperature Tc ] [ Critical Pressure (pc) ]