DENSITY AND VISCOSITY MEASUREMENTS OF AQUEOUS SOLUTIONS OF 2−METHOXYETHANOL AT TEMPERATURES (298.15, 303.15, 308.15, AND 313.15) K

Abstract

Densities and viscosities have been measured for the binary mixtures of 2–methoxyethanol (2– ME) and water at 298.15, 303.15, 308.15 and 313.15 K. From the precise density measurements, the excess molar volume ( E V ) were calculated, V E results are negative over the entire range of mole fractions and become less negative as the temperature increases. The deviation in viscosity (Δη) and excess molar Gibbs free energy of activation of viscous flow (ΔG *E ) have been calculated from experimental viscosity measurements at different temperatures. ηΔ and ΔG *E data are positive over the whole mole fraction range. The observed results of V E , ηΔ and ΔG *E are discussed in terms of molecular interactions in these binary mixtures. Generally, molecular interactions dominant these behaviors are of type, disruption and formation of intra–and interhydrogen bonding between like and unlike molecules, respectively and dipole–dipole interaction. The experimental excess functions V E , ηΔ and ΔG *E were fitted to the Redlich–Kister polynomial equation to evaluate the adjustable parameters and standard deviation from ideality. Introduction 2-Methoxyethanol is the first member of alkoxyalkanols and used extensively as solvent and solublizing agent in many industries with interests ranging from pharmaceutical to plastic products. From theoretical point of view, it is very interesting molecule having the ability to form intra–and intermolecular hydrogen bonds. On the other hand, alkanols (alcohols) are the most well – known solvents with protic and self –associated properties. 2 Methoxyethanol, an ether alkanol, shows physiochemical characteristic midway between protic and dipolar aprotic solvents (1) . Studies on excess functions of binary liquid mixtures are of considerable importance in understanding the nature of molecular interactions that determined by intermolecular forces (hydrogen bonding, charge transfer complex, Van der Waals forces, etc.) (2,3) . To determine the extent and type of interactions between 2–ME and water molecules, the densities and viscosities of binary mixtures of 2-ME with water have been measured. Experimental 2–Methoxyethanol (CH3OCH2CH2OH) was obtained from Aldrich Chemical Company, with purity > 99 %. The solvent was kept on activated molecular sieves type 4 A o for 24 hours then filtered before use. Bidistilled deionized water, its conductivity (0.6 × 10 -6 s.cm 1 ) was used. The experimental measured values of density, ρ and viscosity η for both solvents are agreed well with those values published in the literature (4-8) , Table (1).