Speed of sound in liquid tetrachloromethane and benzene at temperatures from 283.15 K to 333.15 K and pressures up to 30 MPa

https://doi.org/10.1016/j.jct.2004.04.013Get rights and content

Abstract

Speeds of sound in liquid tetrachloromethane and benzene were measured at temperatures from 283.15 K to 333.15 K and pressures up to about 30 MPa. The method used was a sing-around technique employing a fixed path acoustic interferometer operated at a frequency of 2 MHz. The probable uncertainty of the present results is less than ±0.2 percent taking into account the errors of ±20 mK for the temperature, and ±(3 to 5) kPa for the pressure measurements. Measured values are fitted to a polynomial equation as functions of temperature and pressure, and the reliability of the present results is discussed in the light of a comparison with reference data reported in the literature.

Introduction

If a low frequency and low power acoustic wave exited in the sample is propagated isentropically, then the speed of sound, u, has a close relation to the derivative.(∂ρ/∂p)S=u−2,where ρ is density, p is pressure, and S is entropy. This equation is extremely important in obtaining isentropic compressibility, kS=(1/ρ)(∂ρ/∂p)S=1/(ρu2) directly. Compared to other thermodynamic properties, such as the thermal expansion coefficient and specific heat capacity, the speed of sound in a fluid can be measured accurately in wide ranges of temperature and pressure. Consequently, the speed of sound and/or derived properties are frequently employed for evaluation of characteristic properties of liquids and liquid mixtures as reported by many authors, for example, Benson [1], Tamura [2], Aicart [3], and Daridon's groups [4].

Our group has investigated the speeds of sound in the liquid phase of several organic compounds [5], [6] including hydrofluorocarbons [7], [8] in wide ranges of temperature and pressure including the regions near the liquid–vapour coexistence curve and the critical point. The results were found useful in the investigation of thermodynamic and thermophysical properties, and the verification of reliability of equations of state for fluids.

In the course of several past years an experimental technique for the measurements of speed of sound was developed that enabled us to obtain data in wide ranges of temperature and pressure. However, the mechanical determination of the acoustic path length, L, required to obtain the speed of sound, u(u=L/t, where t is the traveling time of an acoustic wave) is difficult because of the electrical coupling between the electric circuit and transducer. Therefore the value of L is determined usually by using the data on speed of sound in a standard compound, such as water or tetrachloromethane, that has low thermal expansion and isothermal compressibility. Moreover to check the influences of L caused by the temperature and pressure change, reliable source on the speed of sound in dense liquid are indispensable in this field.

In this work, the speed of sound in liquid tetrachloromethane, CCl4, and benzene, C6H6, using samples of high purity were measured at temperatures from 283.15 K to 333.15 K and pressures up to 30 MPa. A large number of experimental studies on the sound speed for these compounds have been reported in the literature, but there is no example of research, which correlated and evaluated the latest experiment result, especially those in the compressed liquid. A confirmation of the reliability for new experimental values with the selected reference data will contribute to improve of research in this future field.

Section snippets

Experimental

Samples of CCl4 and C6H6, HPLC grade, were supplied from the Sigma-Aldrich Co. The mass fraction sample purities guaranteed by the manufacturer were >0.999. The substances were used without further purification except careful drying over molecular sieves (4A, 1/16, supplied by Wako Pure Chemicals Ind. Lid).

Speeds of sound were measured using a sing-around technique employing a fixed path acoustic interferometer operated at a frequency of 2 MHz, similar to that described previously [5], [7]. A

Results

The experimental results of speed of sound, u in liquid tetrachloromethane and benzene at several temperatures and pressures are presented in table 1 and FIGURE 1, FIGURE 2. The values at 0.1 MPa were fitted by the equationu/(m·s−1)=∑i=02ai(T/K−298.15)i.The values of the coefficients ai were evaluated using the least-squares analysis of four data points at temperatures from 283.15 K to 333.15 K, and are listed in table 2. A large number of experimental values of the speed of sound in these

Conclusion

In this work, the speed of sound in liquid tetrachloromethane and benzene were measured at temperatures from 283.15 K to 333.15 K and pressure up to about 30 MPa. The uncertainty of the results is estimated to be within ±0.2 percent in the whole experimental range taking into account uncertainties of temperature and pressure. The comparison of the measured data with selected reference values reported recently supports the fact that both the experimental setup and the method employed for the

References (19)

  • G.C. Benson et al.

    J. Chem. Thermodyn.

    (1986)
  • T. Takigawa et al.

    J. Chem. Thermodyn.

    (2000)
  • A.D. Matilla et al.

    J. Chem. Thermodyn.

    (1993)
  • S. Dutour et al.

    J. Chem. Thermodyn.

    (2002)
  • T. Takagi et al.

    Thermochim. Acta

    (1998)
  • T. Takagi et al.

    J. Chem. Thermodyn.

    (2002)
  • K. Tamura et al.

    J. Chem. Thermodyn.

    (1983)
  • M. Bobik et al.

    J. Chem. Thermodyn.

    (1979)
  • A. Lainez et al.

    J. Chem. Thermodyn.

    (1987)
There are more references available in the full text version of this article.

Cited by (0)

View full text
Copyright © 2004 Elsevier Ltd. All rights reserved.