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E-Journal of Chemistry
Volume 8, Issue 3, Pages 1298-1308
http://dx.doi.org/10.1155/2011/402395

Thermodynamic and Calorimetric Study of Acetylsalicylic Acid (Aspirin) and Ibuprofen

Juan Carlos Moreno-Piraján,1 Vanessa Silenia García-Cuello,1,2 and Liliana Giraldo-Gutierréz2

1Grupo de Investigación en Sólidos Porosos y Calorimetría, Departamento de Química, Universidad de los Andes, Carrera 1 No 18 A 10, Bogotá, Colombia
2Facultad de Ciencias, Departamento de Química, Universidad Nacional de Colombia, Carrera 30 No 45-03, Bogotá, Colombia

Received 16 June 2010; Revised 23 November 2010; Accepted 15 December 2010

Copyright © 2011 Hindawi Publishing Corporation. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Enthalpies of solution and dilution of aqueous solutions of sodium acetylsalicylic acid salt and ibuprofen salt were measured with an isoperibolic calorimeter at 293.15 K, 298.15 K, 303.15 K, 308.15 K and 318.15 K. The concentration of the electrolyte was restricted to the solubility of the salt at various temperatures and did not exceed 0.035–0.057 mol kg-1, depending on the temperature studied. The Virial coefficients were derived from Pitzer's model and the excess thermodynamic functions of both the solution and the components of the solution were calculated. An analysis of the thermodynamic characteristics of the solution in terms of concentration and temperature interval was carried out and discussed. Additionally, an analysis was performed by differential scanning calorimetry (DSC).