Thermodynamic and Acoustic Properties of Mixtures of Dibromomethane + Heptane

Abstract

Densities and speeds of ultrasound in binary mixtures of dibromomethane with heptane have been measured within the temperature range from 288.15 K to 318.15 K. From the experimental data, the thermodynamic excess volume, molar isobaric expansion, molar isentropic compression, and ultrasonic speed were calculated. The excess volume and excess isentropic compression have opposite signs, whereas the excess isobaric expansion is an S-shaped function of the mole fraction. An explanation was suggested to account for the excesses in terms of intermolecular interactions. It involved energetic and steric factors. Moreover, it was shown that the positive excess sound speed results almost entirely from the negative excess compression.

Excess Molar Volumes and Speed of Sound in Bromotrichloromethane + n-Heptane, Dibromomethane + n-Heptane, Bromotrichloromethane + Dibromomethane, and Bromotrichloromethane + Bromochloromethane at Temperatures from (293.15 to 313.15) K

“…In this occasion, we report molar excess volumes, V E m , and deviations in isentropic compressibility, Δκ S , obtained from density and speed of sound measurements, respectively, at five temperatures between 293.15 K and 313.15 K and atmospheric pressure, for binary systems bromotrichloromethane or dibromomethane + n -heptane and bromotrichloromethane + dibromomethane or bromochloromethane. The only previous measurements of these mixtures are those of Boquera et al reporting densities of bromotrichloromethane + dibromomethane or bromochloromethane at 298.15 K and those of Przybyla and Chorazewski on densities and speeds of sound of dibromomethane + heptane within the temperature range from 288.15 K to 318.15 K . Our results agree satisfactorily with theirs.…”

Thermodynamic Properties of Dichloromethane, Bromochloromethane, and Dibromomethane under Elevated Pressure: Experimental Results and SAFT-VR Mie Predictions

“…The thermal expansivity, α p , is also obtained during this stage of calculation using eq . The initial values of density and heat capacity are obtained from the polynomial functions (eq ). The requested data of the speed of sound and heat capacity of the dibromomethane as a function of the temperature at atmospheric pressure were taken from our earlier study . In this calculation, a small pressure step of 0.5 MPa is chosen in order to increase the precision of the numerical integration.…”

“…In spite of such wide range of applications and utilizations, there are still gaps in the thermodynamic data sets for haloalkanes under high pressure available, to date, in the open literature. For example, to the best of our knowledge only one data set on the speed of sound in dichloromethane under elevated pressures is available into the literature, while several data sets are available for this property at 0.1 MPa for each investigated liquid. − However, in the case of dichloromethane and dibromomethane, density data and derived properties are also well described at atmospheric pressure, − ,− as well as under high pressure as 12 − and 4 ,− data sets are reported into the literature for pressure up to 51.1 and 70.0 MPa, respectively. Additionally, available experimental data up to 2001 on the compressed liquid density were critically evaluated and fitted by the Tait equation by Cibulka et al while very recently Gonçalves et al reported new density data for dichloromethane under elevated pressures by using a vibrating tube densitometer, for example.…”

“…However, published data for bromochloromethane on the compressed-liquid densities and related quantities are very limited even at 0.1 MPa, ,− ,, and only three high-pressure data sets, − reported only at 298.15 K, for pressure up to 20 MPa are available in the literature. Similarly, heat capacity data of these liquids even at atmospheric pressure are very limited in the open literature, ,− as no data is so far published in the case of the bromochloromethane, for example.…”