resumo
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.
palavras-chave
KNUDSEN EFFUSION; ORGANIC LIQUIDS; ANTHRACENE; THERMOCHEMISTRY; CALORIMETRY; COMBUSTION; SOLIDS; DYES
categoria
Thermodynamics; Chemistry
autores
da Silva, MAVR; Santos, AFLOM; Carneiro, LPT; Mendes, RF; Rodrigues, ASMC; Ferreira, PJO; Ramos, RMC
nossos autores
Ricardo Faria Mendes
Investigadoragradecimentos
Thanks are due to Fundacao para a Ciencia e Tecnologia (FCT), Lisbon, Portugal and to FEDER for financial support given to Centro de Investigacao em Quimica da Universidade do Porto. A.F.L.O.M.S thanks FCT and The European Social Fund (ESF) under the Community Support Framework (CSF) for the award of a post-doctoral fellowship (SFRH/BPD/41601/2007).