Search results for "Enthalpy change of solution"
showing 4 items of 4 documents
Enthalpy of Solution of Nonionic Solutes in Organized Systems
1989
The standard enthalpies of solution of alcohols in micellar solutions of dodecyltrimethylammonium bromide were obtained by direct measurements and by enthalpies of mixing. The observed trends were analyzed with a previously reported model. From the resulting equations, the distribution constant, standard enthalpy of transfer from aqueous to the micellar phase and the standard enthalpy of solution in micellar phase can be calculated at the same time using a linear least-squares analysis. The model seems to hold well also in the case of short chain surfactants and microheterogeneities in spite of the fact that the micellization equilibrium is treated as a pseudo-phase transition.
Thermal Diffusion and Partial Molar Enthalpy Variations of n-Butane in Silicalite-1
2008
International audience; We report for the first time the heat of transfer and the Soret coefficient for n-butane in silicalite-1. The heat of transfer was typically 10 kJ/mol. The Soret coefficient was typically 0.006 K−1 at 360 K. Both varied with the temperature and the concentration. The thermal conductivity of the crystal with butane adsorbed was 1.46 ±0.07 W/Km. Literature values of the isosteric enthalpy of adsorption, the concentration at saturation, and the diffusion coefficients were reproduced. Non-equilibrium molecular dynamics simulations were used to find these results, and a modified heat exchange algorithm, Soft-HEX, was developed for the purpose. Enthalpies of butane were al…
Thermodynamics of Surfactant, Block Copolymer and Their Mixtures in Water: The Role of the Isothermal Calorimetry
2009
The thermodynamics of conventional surfactants, block copolymers and their mixtures in water was described to the light of the enthalpy function. The two methodologies, i.e. the van't Hoff approach and the isothermal calorimetry, used to determine the enthalpy of micellization of pure surfactants and block copolymers were described. The van't Hoff method was critically discussed. The aqueous copolymer+surfactant mixtures were analyzed by means of the isothermal titration calorimetry and the enthalpy of transfer of the copolymer from the water to the aqueous surfactant solutions. Thermodynamic models were presented to show the procedure to extract straightforward molecular insights from the …
Über die lösungswärme von polystyrol in verschiedenen lösungsmitteln
1951
An einem Polystyrol mit einem Molekulargewicht von ca. 20 000 werden die Losungs-warmen in verschiedenen Losungsmitteln in einem Kalorimeter bestimmt. Die meisten Losungsvorgange verlaufen exotherm, in einem Fall (Cyclohexan) wird jedoch bei der Auflosung Warme von der Umgebung aufgenommen. Es wird festgestellt, das die Trocknung der Praparate sehr wichtig fur die Reproduzierbarkeit der Messungen ist. Ferner wird orientierend die Abhangigkeit der Losungswarme vom Polymerisationsgrad sowie von der Konzentration der entstehenden Losung festgestellt. Es wird auserdem orientierend die Mischungswarme von Athylbenzol in verschiedenen Losungsmitteln bestimmt. Measurements of the heat of solution o…