Volumetric and Thermodynamic Studies on Urea–Water System

Urea, as a nonelectrolyte molecular solute in aqueous solutions, has a vital role in the thermodynamic, thermophysical and physiochemical studies. To a large extent, addition of Urea to water does not alter the structural dynamics of water. Only a little amount of water molecules is supposed to be closely associated with urea molecules. Therefore, study of intramolecular as well as intermolecular interactions in the binary aqueous urea solution by conducting thermophysical and thermodynamic investigations is quite important. In this work, new experimental data on water activity for solutions containing urea under precisely controlled conditions and derived thermodynamic parameters were reported. Water activity of urea was also estimated from the Kirkwood–Buff integrals in a novel way.