Densimetric and ultrasonic characterization of urea and its derivatives in water

The densities at T = (288.15, 293.15, 298.15, 303.15, and 308.15) K and sound velocities at T = 298.15 K have been measured for aqueous solutions of urea, N-methylurea, N,N’-dimethylurea, N,N,N’N’-tetramethylurea, N-ethylurea, N,N’-diethylurea, N-butylurea. From these data the apparent molar volumes, VΦ the apparent molar isentropic compressions, KS,Φ, and the Passynski solvation numbers of solutes have been determined. The concentration dependencies of the calculated quantities and their limiting values are discussed in terms of solute–solvent and solute–solute interactions.

► Urea and its alkyl derivatives in aqueous solutions were studied.
► The density and the speed of sound were measured for presented systems.
► The obtained data show clear differences of intermolecular interactions.
► Correlations between properties and group additivity are observed.