New Comment on Gibbs Density Surface of Fluid Argon: Revised Critical Parameters, L. V. Woodcock, Int. J. Thermophys. (2014) 35, 1770-1784

TL;DR

This paper revises the understanding of the critical parameters of fluid argon, arguing that the critical point is a consequence of phase equilibrium conditions rather than an inherent single point, challenging traditional assumptions.

Contribution

It demonstrates that the critical point of fluid argon arises from thermodynamic phase equilibrium conditions, not as an inherent singular point of the van der Waals equation.

Findings

Critical point conditions are derived from phase equilibrium constraints.

The existence of a single critical point is not an inherent property of the fluid.

Thermodynamic derivatives vanish at the critical point under phase equilibrium.

Abstract

It is shown that the existence of single critical point of the fluid described by van der Waals equation of state is not the hypothesis and it is the consequence of the thermodynamic conditions of liquid-vapor phase equilibrium. It is also shown that the thermodynamic conditions of liquid-vapor phase equilibrium of the fluid give equalities to zero of first and second partial derivatives at constant temperature of pressure with respect to volume at critical point which are usual conditions of existence of critical point.