Thermodynamics Research Center / ThermoML | Journal of Chemical Thermodynamics

Development and test of a new Knudsen effusion apparatus for the measurement of low vapour pressures

Fonseca, J. M. S.[Jose M.S.], Pfohl, O.[Oliver], Dohrn, R.[Ralf]
J. Chem. Thermodyn. 2011, 43, 12, 1942-1949
ABSTRACT
A new Knudsen effusion apparatus based on the mass-loss technique was developed. The apparatus was designed for the measurement of vapour pressures below 1 Pa, at temperatures between 250 K and 470 K, using simultaneously up to seven effusion cells. The quality of the results obtained with this new apparatus was verified through the study of two reference compounds, anthracene and phenanthrene. Both the measured vapour pressures and the derived standard molar enthalpies of sublimation are in excellent agreement with values available in the literature for these compounds.
Compounds
# Formula Name
1 C14H10 anthracene
2 C14H10 phenanthrene
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
  • Vapor or sublimation pressure, kPa ; Crystal
  • Temperature, K; Crystal
  • Crystal
  • Gas
  • Calculated from knudsen effusion weight loss
  • 37
  • POMD
  • 2
  • Vapor or sublimation pressure, kPa ; Crystal 2
  • Temperature, K; Crystal 2
  • Crystal 2
  • Gas
  • Calculated from knudsen effusion weight loss
  • 51