Enthalpies and heat capacities of solution of urea and tetramethylurea in water, ethylene glycol and formamide

Enthalpies of solution of urea (U) and tetramethylurea (TMU) in formamide (FA) and ethylene glycol (Eg) have been experimentally determined from (288 to 328) K. Standard enthalpies and heat capacities of solution of non-electrolytes have been computed and compared with those for aqueous solutions. Heat capacities of solution of U and TMU are rather small and positive for both non-aqueous solvents, whereas in cold water the ΔCp0 values for U and TMU reveal different signs. Our comparative analysis indicates that the behavior of both hydrophilic and hydrophobic species in water differs from that in the non-aqueous solvents with the three dimensional H-bond network, according to our experimental results formamide being a more “water-like” solvent than ethylene glycol.