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Ivan Cibulka Lubomír Hnědkovský Josef Šedlbauer 《The Journal of chemical thermodynamics》2010,42(2):198-207
Density data for dilute aqueous solutions of two amino acids (glycine, l-alanine) obtained using a flow vibrating-tube densimeter are presented together with partial molar volumes at infinite dilution (standard molar volumes, ) calculated from the measured data. The experiments were performed at temperatures from (298 up to 443) K at pressures close to the saturation line of water, at pressures in the range from (15 to 17) MPa, and at 30 MPa. Values of an analogue of isothermal compressibility, , are also evaluated. Maxima on the curves and are observed and discussed. The new data along with literature values of standard molar volumes and heat capacities are used for generating the recommended parameterization of an equation of state for standard molar thermodynamic properties of the aqueous amino acids. 相似文献
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Essmaiil Djamali Keith Chen James W. Cobble 《The Journal of chemical thermodynamics》2009,41(9):1035-1041
Standard state thermodynamic properties for aqueous sodium perrhenate at temperature in the range of (298.15 to 598.15) K and at psat were determined by high dilution solution calorimetry down to 10?4 m. Standard state partial molar heat capacities, , of aqueous sodium perrhenate calculated from present study are compared to literature values up to T = 398.15 K. The differences between of and Cl?(aq) at lower temperature is much greater than that due to their internal molecular motions. Consequently, the perrhenate ion appears to have an ionic incomplete primary hydration shell as compared to the chloride ion. The difference in thermodynamic functions has now been well defined up to T = 598.15 K for other important high temperature calculations. 相似文献
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《The Journal of chemical thermodynamics》2007,39(6):888-892
Calcium titanofluoride CaTiF5(s) was prepared by solid-state reaction of CaF2(s) with TiF3(s) and characterized by X-ray diffraction method. The standard molar isobaric heat capacity of CaTiF5(s) was determined by a power compensated differential scanning calorimeter in the temperature from 230 K to 710 K. A solid-state galvanic cell with CaF2 as electrolyte was used to determine the standard molar Gibbs energy of formation of CaTiF5 in the temperature range from 803 K to 1005 K. The galvanic cell can be depicted as:The second law analysis of present data were carried out to derive the standard entropy and the enthalpy of formation and the values derived are 68.7 J · K−1 · mol−1 and −2848.4 kJ · mol−1, respectively. 相似文献
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Jin L. Liu Andrew W. Hakin Gavin R. Hedwig 《The Journal of chemical thermodynamics》2009,41(11):1232-1238
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《The Journal of chemical thermodynamics》2007,39(7):1090-1097
The equilibrium constants K for the ketoreductase-catalyzed reduction reactions (2-substituted cyclohexanone + 2-propanol = cis- and trans-2-substituted cyclohexanol + acetone) have been measured in n-hexane as solvent. The 2-substituted cyclohexanones included in this study are: 2-methylcyclohexanone, 2-phenylcyclohexanone, and 2-benzylcyclohexanone. The equilibrium constants K for the reactions with 2-methylcyclohexanone were measured over the range T = 288.15 to 308.05 K. The thermodynamic quantities at T = 298.15 K are: K = (2.13 ± 0.06); ; ; and for the reaction involving cis-2-methylcyclohexanol, and K = (10.7 ± 0.2); ; ; and for the reaction involving trans-2-methylcyclohexanol. The standard molar Gibbs free energy changes for the reactions (trans-2-substituted cyclohexanol = cis-2-substituted cyclohexanol) in n-hexane have also been calculated and compared with the literature data that pertain to reactions in the gas phase and at higher temperatures. Experiments carried out with a chiral column demonstrated that the enzymatic reduction of 2-phenylcyclohexanone catalyzed by the ketoreductase used in this study is not stereoselective. 相似文献
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