Comments on Failures of van der Waals Equation at the Gas Liquid Critical Point, L. V. Woodcock, International Journal of Thermophysics 2018 39 120

TL;DR

This paper critiques Woodcock's analysis of van der Waals equation failures at the critical point, demonstrating numerous errors and asserting the equation's qualitative validity near critical conditions.

Contribution

It provides a detailed correction and critique of previous work, reaffirming the van der Waals equation's qualitative accuracy near the critical point of argon.

Findings

Woodcock's results contain multiple errors and incorrect conclusions.

Van der Waals equation accurately describes saturation pressure dependencies.

Qualitatively describes coexisting densities and thermodynamic properties near critical point.

Abstract

These comments are a response to the discussion presented in the above paper concerning the New comment on Gibbs Density Surface of Fluid Argon, Revised Critical Parameters by Umirzakov. Here we show that Woodcocks results obtained for the dependencies for the isochoric heat capacity, excess Gibbs energy and coexisting difference functional of argon, and coexisting densities of liquid and vapor of the van der Waals fluid and presented in all Figures are incorrect, his Table includes incorrect values of coexisting difference functional, his paper includes many incorrect equations, mathematical and logical errors and physically incorrect assertions concerning the temperature dependences of the isochoric heat capacity and entropy of real fluids, most of the his conclusions are based on the above errors, incorrect data, incorrect comparisons and incorrect dependencies; and most of his conclusions are invalid. We also show that the van der Waals equation of state quantitatively describes the dependencies of saturation pressure on vapor density and temperature near critical point, and the equation of state can describe qualitatively the reduced excess Gibbs energy, rigidity and densities of coexisting liquid and vapor of argon, including the region near critical point.