Viscosity of Aqueous Solutions of Some Alcohols

Abstract

Viscosities of aqueous solutions of 1-Propanol, 2-Propanol, t-Butanol, allyl alcohol and propargyl alcohol were measured at temperatures 30°, 35°, 40°, 45° and 50°C covering the whole range of composition. On addition of alcohols to water, viscosity increases rapidly. Except for propargyl alcohol, viscosities pass through maxima and then decline continuously as the addition of alcohol is continued. the heights of the maxima occuring between 0.2 and 0.3 mole fraction of alcohols are in the order, t-Butanol > 2-Propanol > 1-Propanol > allyl alcohol. Contrary to this, propargyl alcohol shows no such maximum. After the fast initial rise, the viscosity rises slowly and monotonically up to its pure state for this alcohol. the excess viscosities are found to be positive and large in magnitude. for all alcohols, excess viscosities show maxima in water-rich region. Shallow minima are observed for 2-Propanol and t-Butanol, each at the alcohol-rich end of viscosity curves, which disappear gradually with the rise of temperature. the viscosity and excess viscosity vs. composition curves of all the systems were interpreted mainly in terms of hydrophobic hydration and hydrophilic interaction.