Surface tension and surface excess heats of mixing of <i>n</i>-butyric acid with various solvents

Abstract

Surface tension (σ) of binary mixtures of <i>n</i>-butyric acid (BA) + cyclohexane, + <i>n</i>-octane, + benzene, + toluene, + carbon tetrachloride, + chloroform, + methanol, + acetone, has been measured at 298.15 and 308.15 K over the entire composition range using a differential capillary rise method. The surface tension data have been used to evaluate the excess surface tension (σ^E). It is found that σ^E values, in accordance with the prediction of Gibbs adsorption equation, for the first five of the eight systems negative at both the temperatures while for the remaining three systems are positive. This may be ascribed to the heteromolecular hydrogen bonding.