Volumetric Properties of Aqueous Solutions of Ethylene Glycols in the Temperature Range of 293.15–318.15 K

Abstract

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 V-2,0 were concentration independent and slightly increase with increasing temperature. The partial molar volumes at infinite dilution V-2,0 or the limiting apparent molar volumes of ethylene glycols were fitted to a linear equation with the number of oxyethylene groups (n) in the solute molecule. From this equation a constant contribution of the terminal (OH) and the (CH2CH2O) groups to the volumetric properties was obtained. The thermal expansion coefficient (α1,2) 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 (α1,2) were higher than the value of the thermal expansion coefficient of the pure water.