J Solution Chem (2009) 38: 315–320
DOI 10.1007/s10953-009-9375-6
Effect of Temperature on the Solubility of Short-Chain
Carboxylic Acids in Water
Carmen M. Romero · Felipe Suárez
Received: 22 July 2008 / Accepted: 26 October 2008 / Published online: 27 January 2009
© Springer Science+Business Media, LLC 2009
Abstract The aqueous solubilities of pentanoic and hexanoic acids were measured between
298.15 and 333.15 K at intervals of 5.00 K. Nonlinear dependences were found for the
variation of solubility with temperature. The temperature dependences of the solubility of
the acids in water are described by nonlinear van’t Hoff plots. Experimental data were fitted
by the method of least-squares to a second-order polynomial equation, which was then used
to determine the differential solution enthalpies at selected temperatures. The values for the
apparent Gibbs energy and the apparent entropy of solution are calculated.
Keywords Solubility · Carboxylic acids · Aqueous solutions
1 Introduction
Thermodynamic properties and, in particular, the solubility of aqueous solutions of model
compounds of biological and industrial importance are of considerable interest due do their
practical and theoretical importance. The information obtained is useful in the development
of solution models that describe the thermodynamic properties of carboxylic acid solutions,
and can contribute to the elucidation of the nature of interactions between non-polar and
polar groups with water and to understanding the balance between hydrophobic and hy-
drophilic interactions [1].
The solubility of aqueous solutions of carboxylic acids has been studied before, but most
of the experimental work refers to short-chain organic acids with less than four carbon atoms
on the hydrocarbon chain and to the solubility of long-chain or fatty acids due to their
industrial applications [2–4]. There are only very limited data available for the solubility
of aqueous solutions of carboxylic acids having between three and six carbon atoms [5],
some of these solubility data lack the desired precision, and in most cases the temperature
dependence of the solubility was not reported [6–9].
C.M. Romero ( ) · F. Suárez
Departamento de Química, Facultad de Ciencias, Universidad Nacional de Colombia, Bogotá, Colombia
e-mail: cmromeroi@unal.edu.co