Accurate standard molar enthalpy of formation values in the liquid phase can be obtained by combining high-level quantum chemistry values of gas-phase enthalpies of formation with experimentally determined enthalpies of vaporisation. The procedure is illustrated for 2-, 3-, and 4-methyl-anisoles. Using the W1-F12 and G4 quantum-chemical methods, the gas-phase enthalpies of formation of these compounds at T = 298.15 K were computed. Molar enthalpies of vaporisation for these isomers were measured by the transpiration method. Combining the experimental and the high-level ab initio values, the standard molar enthalpies of formation in the liquid phase for all three isomers were derived and compared with those determined for 2- and 4-methyl-anisoles by using combustion calorimetry.
Compounds
#
Formula
Name
1
CO2
carbon dioxide
2
H2O
water
3
O2
oxygen
4
C8H10O
1-methoxy-2-methylbenzene
5
C8H10O
1-methoxy-3-methylbenzene
6
C8H10O
1-methoxy-4-methylbenzene
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
4
Vapor or sublimation pressure, kPa ; Liquid
Temperature, K; Liquid
Liquid
Gas
Transpiration method
16
POMD
5
Vapor or sublimation pressure, kPa ; Liquid
Temperature, K; Liquid
Liquid
Gas
Transpiration method
13
POMD
6
Vapor or sublimation pressure, kPa ; Liquid
Temperature, K; Liquid
Liquid
Gas
Transpiration method
21
RXND
4
1
2
3
Specific internal energy of reaction at constant volume, J/g
Static bomb calorimetry
1
RXND
6
1
2
3
Specific internal energy of reaction at constant volume, J/g