Comment on “Computation of Isobaric Thermal Expansivity from Liquid Density Measurements. Application to Toluene”

We comment on work by Daridon et al., who proposed a novel method for computing the isobaric thermal expansion coefficient with the use of Mosteller–Tukey linearization of the density as a function of temperature. Since the mentioned work was primarily focused on the data at the standard atmospheric pressure and temperatures below the boiling point, we explore the range of validity of this approach in a more wide range of pressures and temperatures with special attention to the reproducibility of the zero temperature derivative of the expansivity at high pressures. It was found that the Daridon et al.’s method provides an accurate representation of the thermal expansion isobars in the subcritical temperature region up to the temperature where the real dependence has an inflection point. This means that the respective functional form can neither reproduce a finite maximum in the expansivity at supercritical pressures nor the divergence at the critical point. At the same time, within the method’s range of applicability, it allows detecting accurately the location of the points corresponding to the crossing of the thermal expansion isotherms that is demonstrated using the density data as well as the direct measurement of the expansivity through scanning transitiometry.