Abstract
Author(s): M. Kondaiah1, K. Sreekanth2, Sk.Md. Nayeem3and D. Krishna Rao
Densities, ρ and viscosities, η of 0.5 m, 1.0 m and 1.5 m aqueous ethylene glycol and propylene glycol solutions in iso-propanol have been measured over the entire composition range at 308.15 K. From this experimental data, deviation in viscosity, Δη, excess free volume,, excess internal pressure, , excess enthalpy, HEand excess Gibbs free energy of activation of viscous flow, ΔG*Ehave been determined. It has been observed that viscosity increases first and attained a maximum value thereafter decreases. Negative values ofand positive values of Δη,, HE, ΔG*Eare observed over the entire composition range in the mixtures studied. The observed negative and positive values of various excess and deviation parameters are attributed to the existence of strong interactions such as geometrical fitting of smaller molecules into the voids createdby larger molecules in the liquid mixtures. The measured values of viscosity for all the investigated solutions have been compared with the theoretically estimated values using empirical relations such as, Grunberg, Hind and Frenkel