Volume properties of solutions of oleic, linoleic, and linolenic acids in n-hexane and n-heptane at 298.15 K

Densities of solutions of oleic, linoleic, and linolenic acids in n-hexane and n-heptane were measured using a vibrating-tube densimeter at 298.15 K in a concentration range of 0–0.012 molar fractions of solute. The measurement error does not exceed ±5·10⁻⁶ g cm⁻³. The limiting partial molar volumes of fatty acids of the studied series in n-hexane and n-heptane and the excess volume properties of binary mixtures were calculated. On going from oleic to linolenic acid, the number of double bonds (>C=C<) in a solute molecule increases, the hydrocarbon chain length in a solvent molecule decreases, and compactness of the structure packing of the resulting solution increases. This is caused, as a whole, by the enhancement of the n-alkane—acid intermolecular interaction. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 643–647, April, 2006.