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

Excess molar volumes V-m(E) have been measured for binary mixtures of dieth ylene glycol monoethyl ether with methanol, ethanol, 1-propanol, l-pentanol and 1-hexanol as a function of composition using a continuous-dilution dil atometer 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 et her + methanol, + ethanol, and + l-propanol and positive for the remaining systems, diethylene glycol monoethyl ether + l-pentanol, and + 1-hexanol. T he 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 est imate 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 ana lysis of each of the three contributions viz. interactional, free volume an d internal pressure to V-m(E) shows that the free volume effect and interna l pressure contribution are negative for all the mixtures, whereas the inte ractional 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 interactio n parameter) with composition and the number of carbon atoms in the alcohol molecule is discussed.