Computation of Liquid Isothermal Compressibility from Density Measurements: An Application to Toluene

A computation method was developed for estimating the compressibility and its uncertainty from density measurements carried out from atmospheric pressure to 100 MPa. For that purpose, first the ability of 19 equations for fitting density data and for calculating the isothermal compressibility was investigated. Among the equations of state tested, only 6 equations were selected for their suitability for deriving density data in the pressure range investigated. Then, a procedure for evaluating the combined standard uncertainty associated with the determination of the isothermal compressibility from the derivation of density data was tested. Finally, a numerical method was proposed for estimating the isothermal compressibility and its uncertainty from a limited number of experimental density data by considering a Monte Carlo procedure. As an example, the proposed numerical procedure was applied to liquid toluene. With this aim in mind, the density of liquid toluene was measured up to 100 MPa in the temperature range of 293.15-343.15 K by using a U-shape oscillating tube density meter.