Vapour pressures, enthalpies and entropies of sublimation of para substituted benzoic acids

• Type: Article in International Scientific Journal
• Date: 2010

Authors

Manuel J S Monte (Author) FCUP; Luis M N B F Santos (Author) FCUP; Fonseca, JMS (Author) Other; Sousa, CAD (Author) Other

Journal

Title: Journal of Thermal Analysis and Calorimetry

Vol. 100 No. 2

Pages: 465-474

ISSN: 1388-6150

Publisher: Springer Nature

Indexing

ISI Web of Knowledge - 30 Citations

Scopus - 30 Citations

Scientific classification

FOS: Engineering and technology > Chemical engineering

CORDIS: Physical sciences > Chemistry > Organic chemistry ; Physical sciences > Chemistry > Physical chemistry

Other information

Authenticus ID: P-003-73Y

DOI: 10.1007/s10973-009-0649-4

Abstract (EN): The vapour pressures of six para-substituted benzoic acids were measured using the Knudsen effusion method within the pressure range (0.1-1 Pa) in the following temperature intervals: 4-hydroxybenzoic acid (365.09-387.28) K; 4-cyanobenzoic acid (355.14-373.28) K; 4-(methylamino)benzoic acid (359.12-381.29) K; 4-(dimethylamino)benzoic acid (369.29-391.01) K; 4-(acetylamino)benzoic acid (423.10-443.12) K; 4-acetoxybenzoic acid (351.28-373.27) K. From the temperature dependence of the vapour pressure, the standard molar enthalpy, entropy and Gibbs energy of sublimation, at the temperature 298.15 K, were derived for each of the studied compounds using estimated values of the heat capacity differences between the gaseous and the crystalline phases. Equations for estimating the vapour pressure of para substituted benzoic acids at the temperature of 298.15 K are proposed.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 10