Thermodynamics Research Center / ThermoML | Fluid Phase Equilibria

Measurements of the isochoric heat capacity, the critical point (TC, nC) and vapor liquid coexistence curve (TS, nS) of high-purity toluene near the critical point*

Abdulagatov, I. M.[Ilmutdin M.], Polikhronidi, N. G.[Nikolai G.], Bruno, T. J.[Thomas J.], Batyrova, R. G.[Rabiyat G.], Stepanov, G. V.[Genadii V.]
Fluid Phase Equilib. 2008, 263, 1, 71-84
ABSTRACT
Isochoric heat capacities (CV, V, T), phase boundary properties (TS, nS) and the critical (TC, nC) parameters for high-purity (0.9999+ mole fraction) toluene have been measured with a high temperature, high pressure, nearly constant volume adiabatic calorimeter and quasi-static thermogram technique. Measurements were made at three selected liquid and vapor isochores 777.8, 555.25, and 214.64 kgm.3 in the temperature range from 379 to 591 K. For five near-critical isochores 268.68, 281.68, 296.62, 301.52, and 318.28 kgm.3, the measurements were made in the immediate vicinity of the coexistence curve in order to accurately determine the phase transition temperatures (TS, nS) (shape of the coexistence curve near the critical point) and the critical parameters (TC, nC). The total combined uncertainty of heat capacity, density, and temperature measurements were estimated to be less than 2%, 0.06%, and 15 mK, respectively. The uncertainties reported in this paper are expanded uncertainties at the 95% confidence level with a coverage factor of k = 2. The uncertainty of the phase transition and the critical temperature value was 0.02 K. The Krichevskii parameter for some toluene-containing binary mixtures was calculated. The derived values of the Krichevskii parameter were used to estimate the effect of dilute impurities on the critical parameters of toluene. The measured values of saturated density near the critical point were interpreted in terms of the complete scaling theory in order to study singularity behavior of the coexistence curve diameter. The measured isochoric heat capacities and saturated densities were compared with the data reported by other authors and values calculated from an equation of state and other correlations.
Compounds
# Formula Name
1 C7H8 toluene
Datasets
The table above is generated from the ThermoML associated json file (link above). POMD and RXND refer to PureOrMixture and Reaction Datasets. The compound numbers are included in properties, variables, and phases, if specificied; the numbers refer to the table of compounds on the left.
Type Compound-# Property Variable Constraint Phase Method #Points
  • POMD
  • 1
  • Critical temperature, K ; Liquid
  • Liquid
  • Gas
  • derived from Cv measurments
  • 1
  • POMD
  • 1
  • Molar heat capacity at constant volume, J/K/mol ; Liquid
  • Temperature, K; Liquid
  • Liquid
  • Gas
  • Vacuum adiabatic calorimetry
  • 5
  • POMD
  • 1
  • Molar heat capacity at constant volume, J/K/mol ; Gas
  • Temperature, K; Gas
  • Gas
  • Liquid
  • Vacuum adiabatic calorimetry
  • 3
  • POMD
  • 1
  • Mass density, kg/m3 ; Liquid
  • Temperature, K; Liquid
  • Liquid
  • Gas
  • derived from Cv measurments
  • 5
  • POMD
  • 1
  • Mass density, kg/m3 ; Gas
  • Temperature, K; Gas
  • Gas
  • Liquid
  • derived from Cv measurments
  • 3
  • POMD
  • 1
  • Molar heat capacity at constant volume, J/K/mol ; Fluid (supercritical or subcritical phases)
  • Temperature, K; Fluid (supercritical or subcritical phases)
  • Mass density, kg/m3; Fluid (supercritical or subcritical phases)
  • Fluid (supercritical or subcritical phases)
  • Vacuum adiabatic calorimetry
  • 24