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  • 1.
    Aune, Ragnhild, E
    et al.
    KTH, Superseded Departments, Metallurgy.
    Sridhar, S
    Sichen, Du
    A Galvanic Cell Study Of the Ni-W-O System in the Temperature Range 1034-1317 K1994In: Journal of Chemical Thermodynamics, ISSN 0021-9614, E-ISSN 1096-3626, Vol. 26, no 5, p. 493-505Article in journal (Refereed)
    Abstract [en]

    Experimental studies of the standard molar Gibbs free energy of formation of NiWO4 have been carried out using a solid-state galvanic cell involving (zirconium oxide + calcium oxide) electrolyte in the temperature range T = 1034 K to 1317 K. The galvanic cell used can be represented as

    -Pt|{(1 - δ)Ni + δW}(f.c.c.), NiWO4(s), WO2.72(s)|(1 - x)ZrO2 + x CaO|NiO(s), Ni(s)|Pt+,

    where δ « 1. The e.m.f. against temperature plot shows a break at T ≈ 1167 K, indicating a possible phase transformation occurring in the ternary mixture. These studies were complemented by X-ray-diffraction studies of some ternary mixtures equilibrated at T = 1073 K and 1273 K. A thermodynamic assessment of (nickel + tungsten + oxygen) was carried out as part of the present work, incorporating the present results along with those available in the literature for the ternary as well as the three binaries involved. The isothermal sections at T = 1073 K and 1273 K are presented.

  • 2. Ge, Xinlei
    et al.
    Wang, Xidong
    Zhang, Mei
    Seetharaman, Seshadri
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    A new three-particle-interaction model to predict the thermodynamic properties of different electrolytes2007In: Journal of Chemical Thermodynamics, ISSN 0021-9614, E-ISSN 1096-3626, Vol. 39, no 4, p. 602-612Article in journal (Refereed)
    Abstract [en]

    In this study, Guggenheim charging process, which involves the radial Boltzmann distribution, was introduced to develop a new predictive model with three parameters, ion-ion distance parameter, ion-solvent parameter, and solvation parameter. In this model, the ion-ion and ion-solvent molecule interaction are all included in the charging process, and it is independent of the temperature and solvent. This new model was applied to correlate the experimental data from literatures for 208 electrolytes aqueous solution at T = 298.15 K of which the concentration range is wide. The calculated results agreed well with the experimental ones for most electrolytes, especially for the prediction in high ionic strength. The estimation of solvation parameter S also gave that the solvation tendency for cations and anions follow a trend, which is in consistent with results published in literature. Investigations were also been made in calculations for electrolytes solutions at other temperatures and non-aqueous system, which proved this model was also feasible.

  • 3. Kuhs, Manuel
    et al.
    Svärd, Michael
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Transport Phenomena. SSPC, University of Limerick, Ireland.
    Rasmuson, Åke C.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Transport Phenomena.
    Thermodynamics of fenoxycarb in solution2013In: Journal of Chemical Thermodynamics, ISSN 0021-9614, E-ISSN 1096-3626, Vol. 66, p. 50-58Article in journal (Refereed)
    Abstract [en]

    The solubility of fenoxycarb has been determined between 278 and 318 K in several organic solvents. The solid phase at equilibrium and some indication of polymorphism has been properly examined by powder XRD, DSC, Raman and ATR-FTIR spectroscopy, solution H-1 NMR and SEM. Using literature data the activity of the solid phase within a Raoult's law definition has been calculated, based on which solution activity coefficients have been estimated. In ethyl acetate, the van't Hoff enthalpy of solution is constant over the temperature range and equals the melting enthalpy. However, it is shown that the solution is slightly non-ideal with the heat capacity difference term compensating for the activity coefficient term. In toluene, the van't Hoff enthalpy of solution is constant as well but clearly higher than the melting enthalpy. In methanol, ethanol and isopropanol, van Hoff curves are strongly non-linear, the slope however clearly approaching the melting enthalpy at higher temperatures. In all solvents, positive deviations from Raoult's law are prevailing. The activity coefficients follow a decreasing order of isopropanol > ethanol > methanol > toluene > ethyl acetate, and in all solvents decrease monotonically with increasing temperature. The highest activity coefficient is about 18 corresponding to about 2.5 kJ/mol of deviation from ideality.

  • 4.
    Nordström, Fredrik
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Transport Phenomena.
    Rasmuson, Åke C.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Transport Phenomena.
    Determination of the activity of a molecular solute in saturated solution2008In: Journal of Chemical Thermodynamics, ISSN 0021-9614, E-ISSN 1096-3626, Vol. 40, no 12, p. 1684-1692Article in journal (Refereed)
    Abstract [en]

    Prediction of the solubility of a solid molecular compound in a solvent, as well as, estimation of the solution activity coefficient from experimental solubility data both require estimation of the activity of the solute in the saturated solution. The activity of the solute in the saturated Solution is often defined using the pure melt at the same temperature as the thermodynamic reference. In chemical engineering literature also the activity of the solid is usually defined on the same reference state. However, far below the melting temperature, the properties of this reference state cannot be determined experimentally, and different simplifications and approximations are normally adopted. In the present work, a novel method is presented to determine the activity of the solute in the saturated solution (=ideal solubility) and the heat capacity difference between the pure supercooled melt and solid. The approach is based on rigorous thermodynamics, using standard experimental thermodynamic data at the melting temperature of the pure compound and solubility measurements in different solvents at various temperatures. The method is illustrated using data for ortho-, meta, and para-hydroxybenzoic acid, salicylamide and paracetamol. The results show that complete neglect of the heat capacity terms may lead to estimations of the activity that are incorrect by a factor of 12. Other commonly used simplifications may lead to estimations that are only one-third of the correct value.

  • 5. Smith, A. L.
    et al.
    Colle, J. -Y
    Benes, O.
    Konings, R. J. M.
    Sundman, B.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Gueneau, C.
    Thermodynamic assessment of the neptunium-oxygen system: Mass spectrometric studies and thermodynamic modelling2016In: Journal of Chemical Thermodynamics, ISSN 0021-9614, E-ISSN 1096-3626, Vol. 103, p. 257-275Article in journal (Refereed)
    Abstract [en]

    Knudsen effusion mass spectrometry measurements on neptunium dioxide are reported in this work, which have allowed to improve the understanding of its vapourization behaviour and solved discrepancies noticed in the literature: the enthalpy of formation of NpO2(g) has been re-assessed and the composition of neptunia at congruent vapourization has been determined at 2262 K. In addition, a thermodynamic model for the neptunium-oxygen system has been developed using the CALPHAD method. The non stoichiometric NpO2-x phase is described herein using the compound energy formalism with ionic constituents (Np3+, Np4+)(1) (O2-, Va)(2), while the liquid phase is represented with the ionic two-sublattice model (Np4+)(P) (O2-, Va(Q-), O)(Q). The reliability and consistency of all optimized Gibbs energies have been verified by calculating the phase equilibria, thermodynamic data, oxygen chemical potential and equilibrium partial pressures. Finally, a number of ill-defined data in the Np-O system have been identified after critical review of the literature and comparison with the present experimental results and CALPHAD model.

  • 6.
    Svärd, Michael
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology. SSPC, University of Limerick, Ireland.
    Rasmuson, Åke C.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Transport Phenomena. SSPC, University of Limerick, Ireland.
    (Solid + liquid) solubility of organic compounds in organic solvents: correlation and extrapolation2014In: Journal of Chemical Thermodynamics, ISSN 0021-9614, E-ISSN 1096-3626, Vol. 76, p. 124-133Article in journal (Refereed)
    Abstract [en]

    A semi-empirical model is developed for the regression of solid-liquid solubility data with temperature. The model fulfils the required boundary conditions, allowing for robust extrapolation to higher and lower temperatures. The model combines a representation of the solid-state activity which accommodates a temperature-dependent heat capacity difference contribution with a scaled three-parameter Weibull function representing the temperature dependence of the solution activity coefficient at equilibrium. Evaluation of the model is based on previously published experimental calorimetric and solubility data of four organic compounds, fenoxycarb, fenofibrate, risperidone and butyl paraben, in five common organic solvents, methanol, ethyl acetate, acetone, acetonitrile, and toluene. The temperature dependence of the van’t Hoff enthalpy of solution and its components is analysed and discussed. Among the four compounds the influence of temperature on the enthalpy of fusion varies from moderate to substantial. Based on the semi-empirical model, a new equation containing three adjustable parameters is proposed for regression and extrapolation of solubility data for cases when only melting data and solubility data is available. The equation is shown to provide good accuracy and robustness when evaluated against the full semi-empirical model as well as against commonly used, more simple empirical equations. It is shown how such a model can be used to obtain an estimate of the heat capacity difference for cases where accurate solubility data is available in multiple solvents.

  • 7.
    Yang, Huaiyu
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Transport Phenomena.
    Rasmuson, Åke Christoffer
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Transport Phenomena.
    Thermodynamics of molecular solids in organic solvents2012In: Journal of Chemical Thermodynamics, ISSN 0021-9614, E-ISSN 1096-3626, Vol. 48, p. 150-159Article in journal (Refereed)
    Abstract [en]

    The thermodynamics of solid-solution solubility are examined using data for two different compounds: butyl paraben and benzoic acid. Solubility data in different solvents are used to estimate melting properties of the pure solid solutes, and are used to estimate the solid state Gibbs free energy relative to the super cooled melt. The relation to melting data experimentally determined is analysed, and solution activity coefficients are calculated. The work shows that there is a strong relation between solid-liquid solubility data and thermodynamic data of the pure solute. For these compounds, the melting temperature of the pure solute can be fairly accurately estimated by extrapolation of solid-liquid solubility data up to mole fraction equal unity. The estimation of the melting enthalpy is less successful showing deviations in the order of 20% to 30% from the experimental values determined by differential scanning calorimetry. For butyl paraben and benzoic acid, the best estimation of the solid state Gibbs free energy is obtained if DSC determination of melting properties is combined with an estimation of the melt-solid heat capacity difference versus temperature relation by correlation to solubility data.

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