Volumetric Properties of Urea in the Mixture of N,N-Dimethylformamide with Water

Abstract

The density of urea (U) in the mixtures of N,N-dimethylformamide (DMF) and water (H 2 O) was measured within the temperature range of (293.15 to 308.15) K. The results obtained were used to calculate the excess molar volume, V E , of the DMF−H 2 O mixture, apparent molar volumes, V Φ , of DMF in water and of water in DMF, as well as the partial molar volume of urea in a solution at infinite dilution, V m ∞ , within the whole concentration range of the mixed solvent (DMF−H 2 O). The data obtained were discussed from the point of view of temperature changes and interaction in solution.

Partial Molar Volumes of 15-Crown-5 Ether in Mixtures of N,N-Dimethylformamide with Water

“…In the case of the DMF + H 2 O + urea system, the values of b V are negative but they become less negative with increasing water content in the mixtures, which indicates hydrophilic properties of urea and that the solute–solute interactions have become weaker [21]. …”

“…For urea [ 21 ] the decreasing values of V Φ with increasing urea content in the mixture testify to the existence of increasing short range attractions between urea molecules [ 37 ]. In the case of the DMF + H 2 O + urea system, the values of b V are negative but they become less negative with increasing water content in the mixtures, which indicates hydrophilic properties of urea and that the solute–solute interactions have become weaker [ 21 ].…”

“…The data are compared with analogous results previously obtained for the solutions of urea (a hydrophilic compound) in the mixtures of DMF and water [21]. …”

“…In this paper we present the effect of the mixed solvent composition and temperature on the volumetric properties of the system 15C5 + DMF + H 2 O. The data are compared with analogous results previously obtained for the solutions of urea (a hydrophilic compound) in the mixtures of DMF and water [ 21 ].…”

High-Sensitivity Measurement of Density by Magnetic Levitation

“…The ability to resolve very small differences or changes in density-a universal, physical property of matter 1,2 -is important for many applications, such as i) the quality control of manufactured products (e.g., of food, 3 alcoholic contents in liqueur, 4 and biofuel 5 ), ii) the diagnosis of diseases (e.g., by examining biological samples such as urine, 6 and blood, 78,9 iii) and the evaluation of thermophysical properties (e.g., isothermal compressibility coefficient, and thermal expansion coefficient) useful for characterizing and optimizing industrial manufacturing processes involving various substances (e.g., solids, 10 liquids, 11,12 mixtures of liquids, 13 amino acids 14 , polypeptides 15 , drugs 16 , and many others [17][18][19] ). Density is also a parameter used to determine other important properties of material (e.g., elastic modulus, 20,21 compressibility of proteins, 22 stability of pharmaceutical products, 23 and glass-forming ability 24 ) or other types of behaviors (e.g.…”