%0 Journal Article
%T Volumetric Properties of Aqueous Solutions of Ethylene Glycols in the Temperature Range of 293.15¨C318.15£¿K
%A Omer El-Amin Ahmed Adam
%A Ammar Hani Al-Dujaili
%A Akl M. Awwad
%J ISRN Physical Chemistry
%D 2014
%R 10.1155/2014/639813
%X Densities of aqueous solutions of Ethylene glycol (EG), diethylene glycol (DEG), and triethylene glycol (TEG) were measured at temperatures from 293.15 to 318.15£¿K and molalities ranging from 0.0488 to 0.5288£¿mol¡¤kg£¿1. Volumes of all investigated solutions at a definite temperature were linearly dependent on the solute molality; from this dependence the partial molar volumes at infinite dilution were determined for all solutes. It was found that the partial molar volumes at infinite dilution were concentration independent and slightly increase with increasing temperature. The partial molar volumes at infinite dilution or the limiting apparent molar volumes of ethylene glycols were fitted to a linear equation with the number of oxyethylene groups ( ) in the solute molecule. From this equation a constant contribution of the terminal ( ) and the ( ) groups to the volumetric properties was obtained. The thermal expansion coefficient ( ) for all investigated solutions was calculated at temperatures from 293.15 to 318.15£¿K. The thermal expansion coefficients for all solutes increase with increasing temperature and molality. Values of ( ) were higher than the value of the thermal expansion coefficient of the pure water. 1. Introduction Mixing effects for thousands of chemical compounds and their mixtures used in industry are rather difficult to be known; hence, knowledge of thermodynamic properties such as densities, as well as excess molar volumes, , partial molar volumes, and apparent molar volumes of organic mixtures at various temperatures, is of great importance. Solvation of a solute in certain solvent and different types of interactions, solute-solvent and solvent-solvent interactions, are of great importance in physical chemistry [1]. Analysis of multicomponent liquid mixtures in terms of mole fraction or molality and their thermodynamic and volumetric properties are important for the design of industrial processes. These properties are also important in the search of models capable of correlating the molecular structure and macroscopic properties of liquids [2]. During the liquid mixture formation the changes of molecule interactions occur, and difference in the components packing becomes apparent. When there is developed hydrogen bond network in, at least, one of the solvents then the mixture properties change in a special way [3]. The physical properties of liquid mixtures are very important in understanding the nature of molecular interactions between the molecules of liquid mixtures. Such properties of liquid mixtures are useful in designing
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