APPARENT MOLAL VOLUMES AND THERMODYNAMIC QUANTITIES OF VISCOUS-FLOW FOR UREA PLUS AMMONIUM-SULFATE SOLUTIONS

From density measurements, apparent molal volumes (phi(v)) and volumes of transfer (Delta(v,tr)) of urea from water to aqueous ammonium sulp hate solutions have been obtained. Viscosity data obtained for the sys tem : urea + ammonium sulphate + water, have been used to calculate, u sing Eyring equation, the thermodynamic quantities (Delta G, Delta H* and Delta S) of viscous flow. Measurements have been made at 303.15 and 313.15 K over the urea concentration range 0-5 M and ammonium sulp hate concentrations 0.2 and 0.4 M Ammonium sulphate in aqueous solutio ns was found to enhance the water-structure. The results have been int erpreted in the light of the solute-solvent interactions in aqueous me dia.