Apparent molar volumes and apparent molar heat capacities of aqueous d-glucose and d-galactose at temperatures from 278.15 K to 393.15 K and at the pressure 0.35 MPa

Abstract

Apparent molar heat capacities Cp, φand apparent molar volumesVφ were determined for aqueous solutions of d-glucose and d-galactose at temperatures from 278.15 K to 393.15 K and at the pressure 0.35 MPa. The molalities m investigated ranged from 0.05 mol · kg−1to 0.5 mol · kg−1. A vibrating tube densimeter (DMA 512P, Anton PAAR, Austria) was used to investigate the densities and volumetric properties. Heat capacities were obtained using a twin fixed-cell, power-compensation, differential-output, temperature-scanning calorimeter (NanoDSC 6100, Calorimetry Sciences Corporation, Provo, UT, U.S.A.). The calculatedVφ and Cp, φof the solutions were fit to equations that describe the surfaces (Vφ, T, m) and (Cp,φ, T, m). These surfaces showed no dependence of VφorCp, φ on M. Infinite dilution partial molar volumesV2o and heat capacities Cp,2owere obtained over the range of temperature. The Cp,2oandV2o values were found to be large, positive, and to increase with increasing temperature.