(P, Vm, T) Measurements of (toluene + propiophenone) at temperatures from 298.15 K to 328.15 K and at pressures up to 40 MPa
Introduction
Research activities of our laboratory comprise, among others, the systematic measurement of volumetric properties of different groups of organic compounds. Our current project is devoted to the study of liquid systems containing aromatic hydrocarbons with respect to their environmental importance. As a first step, the temperature dependence of densities ρ and excess molar volumes for binary liquid mixtures containing benzene and C3-alkyl derivatives of benzene were measured [1] by a vibrating-tube densimeter between T = 298.15 and T = 328.15 K and at atmospheric pressure. Subsequently the (P, Vm, T) measurements of (benzene + 1,3,5-trimethylbenzene) at temperatures from 298.15 K to 328.15 K and at pressures up to 40 MPa [2] and of acetophenone with four aromatic hydrocarbons at two temperatures and atmospheric pressure [3] were carried out.
To our knowledge, there exist no volumetric data for the liquid phase of the system toluene + propiophenone at elevated pressures. Therefore we have measured densities and calculated isothermal compressibilities and excess volumes of the system. The apparatus based on a high-pressure vibrating-tube densimeter working in a static mode [4] and designed for measuring the (p, Vm, T) behaviour of pure liquids and liquid mixtures at elevated temperatures (283 K to 333 K) and moderately high pressures (to 40 MPa) was used for the measurements. The measurements were carried out at the temperatures 298.15 K, 308.15 K, 318.15 K, and 328.15 K and in the pressure range 0.1 MPa to 40 MPa.
The densities and excess volumes of the investigated liquids and their mixtures are required, for instance, for relating excess enthalpy and excess Gibbs energy values. From a practical point of view, the data are useful for the design of mixing, storage, and process equipment. Last but not least, the data measured reflect interactions between the molecules of the mixtures studied and can serve for testing the theories of the liquid state.
Section snippets
Materials
The toluene (Fluka CHROMASOLV, g.c. mass fraction > 0.999) and propiophenone (Fluka, purum, g.c. mass fraction ⩾0.99) were used without further purification. Toluene was dried and stored over 0.4 nm molecular sieves. In order to check the purity of the compounds, their densities and refractive indices were determined at T = 298.15 K and compared with literature values [5], [6], [7]. The agreement was found, in general, to be good (table 1). The purity of the chemicals was checked by gas
Densities
The results of the density measurements are given in table 2. Densities of the pure substances and of 9 weighed mixtures were measured at 23 pressures over the range 0.1 MPa to nearly 40 MPa.
The isothermal densities of pure substances and their mixtures at a given composition were fitted to the Tait equationwhere ρ0 is the density at a reference pressure p0 (p0 = 0.101325 MPa in this work). The values of ρ0 were those obtained by measuring the liquid samples with a
Acknowledgements
The authors acknowledge the partial support of the Grant Agency of the Czech Republic. The work has been carried out under Grant No. 203/02/1098.
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