Scaling analysis of thermodynamic properties in the critical region of fluids

Abstract

A review of the scaled equation of state proposed for the critical region of fluids and magnets is given using the language appropriate for fluids. The experimental evidence for the validity of the basic hypothesis underlying this equation of state is discussed in detail. Experimental data in the critical regions of CO₂, Xe. and He⁴ are then analyzed using a closed-form expression for the chemical potential as a function of density and temperature, based on scaling ideas. Agreement between the proposed equation and the experimental data is found for the three substances. The results of the scaling of Δ<i>μ</i>, Δ<i>ρ</i>, <i>t</i> data are shown not to be in contradiction with the analysis, also based on scaling ideas, of independent experimental measurements of both specific heat and vapor pressure.