Sound Velocity and Molecular Sound Velocity in Aqueous Sugar Solutions

Abstract

Ultrasonic velocity was measured on various sugar solutions (erythrite, fructose, mannite, rhamnose, sucrose, lactose and raffinose) by the method of ultrasonic interferometry at 1. 43Mc/sec and at temperatures between 5℃ and 30℃. Rao's molecular sound velocity was calculated for these solutions and was observed that the molecular sound velocity was a linear function of the concentration (=molar fraction of the solute) within the range of the concentrations investigated (up to about 20% in weight). The molecular sound velocities corresponding to the supercooled liquid states of the solute, as obtained by extrapolation from these straight lines, proved to be smaller than the values calculated from the additivity rules of the molecular sound velocity by employing Rao's atomic increments by about 10 to 20%. This may presumably be due to the effect of the branching of the sugar molecules.