Heat-capacity measurements of aqueous solutions of mono-, di-, and tri-saccharides using an isoperibol twin calorimeter

Abstract

An isoperibol twin calorimeter of dry-shield type was constructed and the specitic heat capacities of D (−)-fructose, D(+)-glucose, D(+)-galactose, D(+)-mannose, D(+)-lactose, D(+)-maltose, and D(+)-raffinose in aqueous solution have been determined at about 303K. The partial molar heat capacity at infinite dilution C ∞ p,2 = C ∞ p,ф was determined by the least-squares application of the relation: mC p,ф = bm + cm 2 . The specific heat capacities of the solutes (except raffinose) in the solid state have also been measured from 270 to 325 K using an adiabatic scanning calorimeter. C ∞ p ,2 and (Δ C ∞ p ,2 = C ∞ p ,2 − C * p ,2 ) are positive for all compounds and increase from mono- to tri-saccharides. The additivity parameters for C ∞ p ,2 of saccharides are different from those for other organic solutes. The results are discussed in relations to other properties such as hydration number and diffusion constant.