ABSTRACT

The Knudsen mass-loss effusion technique was used to measure the vapour pressures at different temperatures of the following halobenzoic acids: 2-chlorobenzoic acid, between T = (320.16 and 339.15) K, 3-chlorobenzoic acid, between T = (320.13 and 340.13) K, 4-chlorobenzoic acid, between T = (333.15 and 356.14) K, 2-bromobenzoic acid, between T = (327.56 and 347.68) K, 3-bromobenzoic acid, between T = (327.67 and 347.60) K and 4-bromobenzoic acid, between T = (348.67 and 366.65) K. From the temperature dependence of the vapour pressure of the crystalline compounds, the standard, p = 105 Pa, molar enthalpies, entropies and Gibbs energies of sublimation at T = 298.15 K, were derived. A d.s.c. study of the fusion of the crystals is also presented.

Compounds

#	Formula	Name
1	C7H5BrO2	4-bromobenzoic acid
2	C7H5ClO2	2-chlorobenzoic acid
3	C7H5ClO2	3-chlorobenzoic acid
4	C7H5ClO2	4-chlorobenzoic acid
5	C7H5BrO2	2-bromobenzoic acid
6	C7H5BrO2	3-bromobenzoic acid

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	Phase	Method	#Points
POMD	1	Molar enthalpy of transition or fusion, kJ/mol ; Crystal		Crystal Liquid Air at 1 atmosphere	DSC:FP	1
POMD	1	Normal melting temperature, K ; Crystal		Crystal Liquid Air at 1 atmosphere	DTA:FP	1
POMD	1	Vapor or sublimation pressure, kPa ; Crystal	Temperature, K; Crystal	Crystal Gas	Calculated from knudsen effusion weight loss	39
POMD	2	Molar enthalpy of transition or fusion, kJ/mol ; Crystal		Crystal Liquid Air at 1 atmosphere	DSC:FP	1
POMD	2	Normal melting temperature, K ; Crystal		Crystal Liquid Air at 1 atmosphere	DTA:FP	1
POMD	2	Vapor or sublimation pressure, kPa ; Crystal	Temperature, K; Crystal	Crystal Gas	Calculated from knudsen effusion weight loss	27
POMD	3	Molar enthalpy of transition or fusion, kJ/mol ; Crystal		Crystal Liquid Air at 1 atmosphere	DSC:FP	1
POMD	3	Normal melting temperature, K ; Crystal		Crystal Liquid Air at 1 atmosphere	DTA:FP	1
POMD	3	Vapor or sublimation pressure, kPa ; Crystal	Temperature, K; Crystal	Crystal Gas	Calculated from knudsen effusion weight loss	27
POMD	4	Molar enthalpy of transition or fusion, kJ/mol ; Crystal		Crystal Liquid Air at 1 atmosphere	DSC:FP	1
POMD	4	Normal melting temperature, K ; Crystal		Crystal Liquid Air at 1 atmosphere	DTA:FP	1
POMD	4	Vapor or sublimation pressure, kPa ; Crystal	Temperature, K; Crystal	Crystal Gas	Calculated from knudsen effusion weight loss	31
POMD	5	Molar enthalpy of transition or fusion, kJ/mol ; Crystal		Crystal Liquid Air at 1 atmosphere	DSC:FP	1
POMD	5	Normal melting temperature, K ; Crystal		Crystal Liquid Air at 1 atmosphere	DTA:FP	1
POMD	5	Vapor or sublimation pressure, kPa ; Crystal	Temperature, K; Crystal	Crystal Gas	Calculated from knudsen effusion weight loss	26
POMD	6	Molar enthalpy of transition or fusion, kJ/mol ; Crystal		Crystal Liquid Air at 1 atmosphere	DSC:FP	1
POMD	6	Normal melting temperature, K ; Crystal		Crystal Liquid Air at 1 atmosphere	DTA:FP	1
POMD	6	Vapor or sublimation pressure, kPa ; Crystal	Temperature, K; Crystal	Crystal Gas	Calculated from knudsen effusion weight loss	26

Thermodynamics Research Center / ThermoML | Journal of Chemical Thermodynamics

Thermodynamic study of the sublimation of six halobenzoic acids

Ribeiro da Silva, M. A. V.[Manuel A. V.], Fonseca, J. M. S.[Jose M.S.], Carvalho, R. P. B. M.[Rui P.B.M.], Monte, M. J. S.[Manuel J. S.]

ABSTRACT