Lecture Notes on Solution Chemistry

Low-temperature heat capacity of the azeotropic mixture composed of water+ethanol+benzene

“…Compared the data in Table 1, the phase transition temperatures of ethanol and benzene in the mixture are lower than those of pure ethanol and benzene. The addition of alcohol to water decrease both the freezing points [22]. But the phase transition temperature of water in the mixture is higher than that of pure water.…”

Simultaneous XRD-DSC Measurements of Water-2-Propanol at Sub-Zero Temperatures

“…× 4 mm) containing the A simultaneous low-temperature X-ray powder-diffractometric (XRD)-DSC technique was applied to the solid state and melting process of frozen aqueous solutions of 2-propanol. 1 H NMR spectra were also obtained at low temperatures. The chemical shifts of the CH3 proton and the CH proton can be classified into four temperature regions: higher than -20˚C, around -20˚C, -50 to -20˚C, and lower than -50˚C.…”

“…The addition of alcohol to water decreases both its freezing and boiling points, and increases its vapor pressure and surface tension. 1 Recently, the structure of water-alcohol solutions over the whole composition region has been extensively studied by X-ray diffraction, 2 NMR, 3 mass spectrometry, 4,5 dielectric measurements, 6,7 and thermodynamic calculations. 8,9 These studies focused on the change in the structure of the cluster formed by water and alcohol molecules as the composition of the solution varied.…”

Hydrophobic Interactions in Aqueous Solutions: Their Operation in Living Systems

“…1 By their mutual interactions, a three-dimensional hydrogenbonded structural network is established, which is highly adaptable to changes in conditions. 2 Quantitative data refer to the 'diffusionally averaged structure' 3 with relaxation times of 10 Ϫ 11 s. 4 Modern computational calculation methods have been applied to systems containing a number of molecules comparable to that in bulk systems. [5][6][7] However, it has not been possible to determine precisely the optimal configuration for the idealized unit of trimeric water, 8 such as has been obtained for the dimeric unit.…”

“…9 The present situation has been characterized as follows: 10 'No theory on water structure has been proposed that is predictive, theoretically sound and suitable to account for the quality of the liquid. ' Because liquid water is actually a solution from which the last traces of both hydrophilic and hydrophobic solutes cannot be removed, 2,[11][12][13] we suggested extending the molecular concept and treating the liquid under consideration as a highly differentiated, well organized, flexible macromolecule. [11][12][13] In order to gain an understanding of the qualities, we started from the wealth of observations under complex conditions and took into consideration the unavoidable presence of both hydrophilic and hydrophobic solutes.…”