Thermodynamics Research Center / ThermoML | Fluid Phase Equilibria

Isochoric heat capacity measurements for H2O+CH3OH mixture in the near-critical and supercritical regions

Polikhronidi, N. G., Abdulagatov, I. M., Stepanov, G. V., Batyrova, R. G.
Fluid Phase Equilib. 2007, 252, 1-2, 33-46
ABSTRACT
The isochoric heat capacity of two (0.5004 and 0.5014 mole fraction of methanol) H2O+CH3OH mixtures has been measured in a range of temperatures from 371 to 579K and densities between 214 and 394 kgm.3. Measurements were made with a high-temperature, high-pressure, nearly constant-volume adiabatic calorimeter. The measurements were performed in the one- and two-phase regions including the coexistence curve, and in the near-critical and supercritical regions. Temperatures at the phase transition curve TS( I) for each of the measured densities and the critical parameters (TC and IC) for the 0.4996H2O+ 0.5004CH3OH mixture were obtained using the method of quasi-static thermograms. The uncertainty of the heat-capacity measurements is estimated to be 2%. Uncertainties of the density, temperature and concentration measurements are estimated to be 0.15%, 15mK and 5 ~10.5 mole fraction, respectively. The derived values of the critical parameters, together with published data, were used to calculate the value of the Krichevskii parameter. The near-critical isochoric heat capacity behavior for the 0.4996H2O+ 0.5004CH3OH mixture was studied using the principle of isomorphism of the critical phenomena in binary mixtures.
Compounds
# Formula Name
1 CH4O methanol
2 H2O water
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
  • 2
  • Molar heat capacity at constant volume, J/K/mol ; Liquid
  • Temperature, K; Liquid
  • Mole fraction - 1; Liquid
  • Liquid
  • Gas
  • Small (less than 1 g) adiabatic calorimetry
  • 8
  • POMD
  • 1
  • 2
  • Molar heat capacity at constant volume, J/K/mol ; Gas
  • Temperature, K; Gas
  • Mole fraction - 1; Gas
  • Gas
  • Liquid
  • Small (less than 1 g) adiabatic calorimetry
  • 2
  • POMD
  • 1
  • 2
  • Mass density, kg/m3 ; Liquid
  • Temperature, K; Liquid
  • Mole fraction - 1; Liquid
  • Liquid
  • Gas
  • derived from heat capacity measurements
  • 8
  • POMD
  • 1
  • 2
  • Mass density, kg/m3 ; Gas
  • Temperature, K; Gas
  • Mole fraction - 1; Gas
  • Gas
  • Liquid
  • derived from heat capacity measurements
  • 2
  • POMD
  • 1
  • 2
  • Molar heat capacity at constant volume, J/K/mol ; Fluid (supercritical or subcritical phases)
  • Mole fraction - 1; Fluid (supercritical or subcritical phases)
  • Mass density, kg/m3; Fluid (supercritical or subcritical phases)
  • Temperature, K; Fluid (supercritical or subcritical phases)
  • Fluid (supercritical or subcritical phases)
  • Small (less than 1 g) adiabatic calorimetry
  • 138