Volumetric and Ultrasonic Velocity Studies of Urea and Thiourea in Aqueous Solution

The observations on the anomalous behavior of urea and the comparison between urea and thiourea in aqueous solutions have been examined by volumetric and ultrasonic sound velocity techniques at different temperature (298.15, 303.15, 308.15, 313.15, 318.15 and 323.15 K), atmospheric pressure by using a high accuracy vibrating U-tube digital density and ultrasonic sound velocity analyzer. The apparent molar volume (phi(v)) & apparent molar adiabatic compressibility (phi(k)) have been calculated from experimental density and ultrasonic sound velocity data respectively and limiting apparent molar volume (phi(v)(0)), limiting apparent molar adiabatic compressibility (phi(k)(0)) have been evaluated from apparent molar volume vs. molality plot as intercept. Apparent molar expansibility (phi(E)) was determined from apparent molar volume and hydration number (n(H)) from adiabatic compressibility. The results show very interesting information about strong solute-solvent & solute-solute interactions, and also elaborate the structure making or breaking behavior in the solution mixtures.