Excess molar volumes and excess partial molar volumes of diethylene glycol monoethyl ether-n-alcohol mixtures at 298.15 K

Excess molar volumes V-m(E) have been measured for binary mixtures of diethylene glycol monoethyl ether with methanol, ethanol, 1-propanol, l-pentanol and 1-hexanol as a function of composition using a continuous-dilution dilatometer at 298.15 K. The excess molar volumes V-m(E) are negative over the entire range of composition for the systems diethylene glycol monoethyl ether + methanol, + ethanol, and + l-propanol and positive for the remaining systems, diethylene glycol monoethyl ether + l-pentanol, and + 1-hexanol. The measured V-m(E) values increase towards positive direction with increase in chain length of the n-alcohol. The V-m(E) results have been used to estimate the excess partial molar volumes V-m(,i)E of the components and have also been analysed using the Prigogine-Flory-Patterson (PFP) theory. An analysis of each of the three contributions viz. interactional, free volume and internal pressure to V-m(E) shows that the free volume effect and internal pressure contribution are negative for all the mixtures, whereas the interactional contribution is negative for methanol and positive for remaining systems. The behaviour of V-m(E), V-m(,i)E, and chi(12) (Flory's interaction parameter) with composition and the number of carbon atoms in the alcohol molecule is discussed.