Thermodynamic study of 9-anthracenecarboxylic acid

The standard massic energy of combustion, in oxygen, of the crystalline 9-anthracenecarboxylic acid was measured, at T=298.15 K, by static-bomb combustion calorimetry, from which the standard molar enthalpy of formation, in the condensed phase, was calculated as Delta(f)H degrees(m)(cr) = -(267.3 +/- 3.4) kJ . mol(-1). The standard molar enthalpy of sublimation of this acid, at T=298.15K, Delta(g)(cr)H degrees(m) = (139.4 +/- 0.9) kJ . mol(-1), was determined from the temperature-vapour pressure dependence, obtained by the Knudsen mass-loss effusion method. From the data presented above, the standard molar enthalpy of formation, in the gaseous phase, at T = 298.15 K, was derived, Delta(f)H degrees(m)(g) = -(127.9 +/- 3.5) kJ . mol(-1). The experimental result is interpreted in terms of enthalpic increments, molecular structure and compared with structurally similar compounds. (C) 2010 Elsevier Ltd. All rights reserved.