Effects of hydration on the thermodynamic properties of aqueous ethylene glycol ether solutions

The densities and isobaric specific heat capacities of binary mixtures of water with various open-chain and cyclic ethylene glycol ethers have been measured at 298.15 K using vibrating tube densimetry, and flow or differential scanning calorimetry, respectively. Excess molar volumes were derived over the whole composition range. Molar isobaric heat capacities and the relative apparent thermodynamic quantities were determined in the water-rich region. The data reflect the changes in the structure and hydrogen-bond dynamics of water caused by these non-ionic solutes. The observed effects are discussed in terms of the influence of hydrophobic hydration on the thermodynamic properties of aqueous solutions. Correlations are given that enable the prediction of the thermodynamic properties of open-chain and cyclic oligo(ethylene oxide) ethers in their pure liquid state and at infinite dilution in water.