Calculation of the thermodynamic and transport properties of aqueous species at high pressures and temperatures: Standard partial molal properties of organic species

The temperature dependence of limiting apparent molal volumes Φ°υ in water for some alcohols (methanol, ethanol, 1-propanol, 2-butanol, 3-pentanol, 3-hexanol, 2,5-hexanediol, cyclopentanol, cyclohexanol, cycloheptanol, and 1,4-cyclohexanediol) and ethers (trimethylene oxide, tetrahydrofuran, tetrahydropyran, 1,3-dioxolane, 1,3-dioxane, 1,4-dioxane, 1,3-dioxepane, 1,3,5-trioxane, dimethoxymethane, 1,2-dimethoxyethane, diethoxymethane, and diethyl ether) has been studied in the temperature range 10–50°C by means of an automatic digital-readout dilatometer. Values of the thermal expansion coefficient α* = (1/Φ°υ)(∂Φ°υ/∂T)p have been obtained at several temperatures and discussed together with literature data on expansibilities of related compounds. The data show a wide spectrum of values of α* at low temperatures which is narrowed at the higher ones. The expansibilities of monofunctional alcohols increase with increasing temperature; the opposite effect is observed for polyhydric alcohols. The α*'s of ethers are very slightly temperature dependent and are much higher, at low temperature, than those of alcohols having the same ratio ofno/nc. These results are discussed in terms of solutewater interactions, and a possible interpretation is put forward.

Partial molal expansibilities of organic compounds in aqueous solution. I. Alcohols and ethers

Group additivity equations of state for calculating the standard molal thermodynamic properties of aqueous organic species at elevated temperatures and pressures.

Densities and volume properties of (water + tert-butanol) over the temperature range of (274.15 to 348.15) K at pressure of 0.1 MPa

Thermodynamic data were used to calculate the Kirkwood−Buff integrals for the aqueous solutions of methanol, ethanol, propanols, and butanols. The calculated values have been compared to those obtained from small-angle X-ray scattering (SAXS) experiments, and satisfactory agreement was found. Improved expressions have been suggested and used to calculate the excess number of molecules around central ones. On this basis, information about the structure of the solutions was gathered, the main conclusion being that the interactions among similar molecules prevail; this leads to clustering dominated by the same kind of molecules.

Felix. Franks

Papers

Precision densities of dilute aqueous solutions of the isomeric butanols