Mercedes Pintos

Refractive indexes of binary mixtures of tetrahydrofuran with 1-alkanols at 25°C and temperature dependence of n and ρ for the pure liquids

Refractive indexes at 25°C were measured for binary mixtures of tetrahydrofuran with 1-hexanol, 1-heptanol, 1-octanol, 1-nonanol, and 1-decanol. Densities, from which excess molar volumes were derived, were measured at the same temperature for the system tetrahydrofuran + 1-decanol. Refractive indexes and densities for the pure compounds were determined at 11 temperatures between 20 and 30°C. The thermal expansion coefficients and the temperature derivatives of the refractive index for these liquids were calculated at 25°C. The temperature dependence of the molar refraction was also examined. The contribution to the molar refraction of a CH2 group was calculated as was the difference between contributions from CH3 and CH2OH groups. The change of molar refraction on mixing is d iscussed in terms of molecular interactions and alkyl chain length.

Prediction of excess volumes and excess surface tensions from experimental refractive indices

Abstract Refractive indices for the binary liquid mixtures: {hexane or heptane + ethanol}, {o-xylene + benzene} and {cyclohexane + benzene, toluene or hexane} were measured at 298.15 K. Excess refractive indices were calculated and fitted to a Redlich-Kister function. Using some mixture rules (Lorentz-Lorenz, Dale -Gladstone, Eykman, Oster, Arago-Biot and Newton), predictions for vE have been made and compared with experimental data taken from the literature. Furthermore the Sugden equation has been used in two different ways for predicting excess surface tensions: the first one starting from densities and the other one from refractive indices. Results are plotted together with the literature data.

Excess volumes and excess heat capacities of some mixtures: (an isomer of hexanol + an n-alkane) at 298.15 K

Abstract Excess molar volumes V m E at 298.15 K were obtained, as a function of mole fraction x for the ten mixtures { x C 6 H 13 OH + (1 − x )C 6 H 14 }; { x C 3 H 7 CH(CH 3 )CH 2 OH + (1 − x )C n H 2 n + 2 } for n = 6, 7, 10, and 14; { x (CH 3 ) 2 CHCH 2 CH(OH)CH 3 + (1 − x )C 6 H 14 }; { x C 2 H 5 CH(CH 3 )CH(OH)CH 3 + (1 − x )C n H 2 n + 2 } for n = 6 and 7; { x C 2 H 5 C(CH 3 )(OH)C 2 H 5 + (1 − x )C n H 2 n + 2 } for n = 6 and 7, from measurements of the density with a vibrating-tube densimeter. The excess molar volumes are either positive or positive-negative. The largest negative value of V m E is found for { x C 6 H 13 OH + (1 − x )C 6 H 14 }: | V m E |(max) = 0.252 cm 3 · mol −1 at x = 0.6451 the largest positive value being found for { x C 3 H 7 CH(CH 3 )CH 2 OH + (1 − x )C 14 H 30 }: V m E (max) = 0.507 cm 3 · mol −1 at x = 0.5058. In addition, a Picker flow microcalorimeter was used to determine excess molar heat capacities C p , m E at constant pressure at 298.15 K for five of these mixtures each with n = 6. The C p , m E s are positive in all cases, but are represented by rather asymmetrical curves of different shape depending upon whether the alkanol is primary, secondary, or tertiary.

Excess enthalpies of (secondary amine + alcohol) at 298.15 K

The excess enthalpies HmE of N-butyl methyl amine + 1-butanol, + 1-pentanol, and + 1-hexanol and of dibutylamine + 1-propanol, + 1-butanol, + 1-pentanol, + 1-hexanol, and + 1-heptanol were measured at 298.15 K, and normal atmospheric pressure, using a Calvet microcalorimeter. All mixtures give HmE < 0; the values do not vary significantly when the chain length of the alcohol increases.

Excess enthalpies of (propyl ethanoate or ethyl propanoate + an n-alkane) at 298.15 K

Abstract The excess molar enthalpies H m E of (an ester + an n -alkane) have been determined experimentally at 298.15 K and normal atmospheric pressure in a Calvet microcalorimeter. A variable-degree polynomial has been fitted to the experimental results.

Densities and Viscosities of the Binary Mixtures Decanol + Some n-Alkanes at 298.15 K

Abstract Densities and viscosities of four binary liquid systems decanol +n-heptane, +n-octane, +n-nonane, +n-decane, have been determined at 298.15 K and atomospheric pressure, over the complete composition ranges. The excess values of molar volume, viscosity and Gibbs free energy for the activation of flow were evaluated. The Grunberg-Nissan parameter was also calculated. The viscosity data were fitted to the equations of McAllister and Auslander.

Excess enthalpies of (n-alkanol + dipropylether), (n-alkanol + 1,2-diethoxyethane), and (n-alkanol + 2-ethoxyethanol) at 298.15 K

Abstract Using a Calvet microcalorimeter, we have determined at 298.15 K and normal atmospheric pressure the excess molar enthalpies HmE of binary mixtures formed by dipropylether, 1,2-diethoxyethane, or 2-ethoxyethanol as one component and 1-butanol, 1-pentanol, or 1-hexanol as the other. A variable-degree empirical polynomial in the mole fraction of n-alcohol has been fitted to the results.

Excess molar volumes of (o-xylene + n-heptane + toluene or n-hex-1-ene) at the temperature 298.15 K

Excess molar volumes at the temperature 298.15 K of ( o -xylene + n -heptane), ( o -xylene + toluene), ( o -xylene + n -hex-1-ene), ( n -heptane + toluene), ( n -heptane + n -hex-1-ene), ( o -xylene + n -heptane + toluene), and ( o -xylene + n -heptane + n -hex-1-ene) have been determined from density measurements. Variable-degree polynomials have been fitted to the results.

Excess enthalpies of (n-alkanol + ethyl ethanoate or ethyl propanoate) at 298.15 K

The excess molar enthalpies HmE of various binary liquid mixtures of (an n-alkanol + an ester) have been determined at atmospheric pressure and 298.15 K using a Calvet microcalorimeter. A variable-degree polynomial has been fitted to the results, which have been interpreted in terms of a “free-volume” model.

Excess Molar Volumes at the Temperature 308.15 K of the Ternary Mixtures (o-Xylene + n-Heptane + Toluene Or n-Hex-1-Ene)

Abstract Excess molar volumes at the temperature 308.15 K were obtained for the mixture (o-xylene + n-heptane), (o-xylene + toluene), (o-xylene + n-hex-1-ene), (n-heptane + toluene), (n-heptane + n-hex-1-ene), (o-xylene + n-heptane + toluene), and (o-xylene + n-heptane + n-hex-1-ene) from density measurements with a vibrating-tube densimeter. Variable-degree polynomials have been fitted to the results and several ways of predicting the excess volumes of the ternary mixture from experimental results for the binary mixtures are compared. Some of the experimental values are used to test the predictions of the Nitta-Chao model.