Apparent Molar Volume and Viscosity Studies on Some Carbohydrates in Solutions

Abstract

The apparent molar volume (φv) and viscosity (η) of L(+)-arabinose, D(+)-galactose, D(−)-fructose, D(+)-glucose, sucrose, lactose, and maltose in water and in 0.1% and 0.3% water-Surf Excel solutions were measured as a function of solute concentrations at 308.15, 313.15, and 323.15 K, respectively. The apparent molar volume (φv) of the carbohydrates was found to be a linear function of the concentration. From a φv versus molality (b) plot, the apparent molar volume at infinite dilution ( ), which is practically equal to the partial molar volume at infinite dilutions ( ) of these substances was determined. The viscosity coefficients B and D for the carbohydrates were calculated on the basis of the viscosity of the solutions and the solvent using the Jones-Dole equation. The activation free energy for viscous flow (ΔG ≠) of the solutions was also calculated using the Eyring equation. The carbohydrates showed structure making behaviour both in water and in water-Surf Excel solutions. When water-Surf Excel solutions and pure water solutions containing carbohydrate molecules are compared, the former were found to be more structured. The behaviour of these solutes in water and in water-Surf Excel solution systems is discussed in the light of solute–solvent interactions.