| 1. |
- Aune, Ragnhild, E, 1965-, et al.
(författare)
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A Galvanic Cell Study Of the Ni-W-O System in the Temperature Range 1034-1317 K
- 1994
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Ingår i: Journal of Chemical Thermodynamics. - : Elsevier BV. - 0021-9614 .- 1096-3626. ; 26:5, s. 493-505
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 2. |
- Cabeza, O., et al.
(författare)
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Tuning physical properties and mesomorphic structures in aqueous 1-ethyl-3-methylimidazolium octylsulfate rigid-gel with univalent salt doping
- 2017
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Ingår i: Journal of Chemical Thermodynamics. - : Elsevier BV. - 0021-9614 .- 1096-3626. ; 112, s. 267-275
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Tidskriftsartikel (refereegranskat)abstract
- We report measurements of density, viscosity and electrical (ionic) conductivity of three aqueous mixtures of 1-ethyl-3-methyl imidazolium octyl-sulfate ([EMIm][OSO4] or C(2)C(1)Im-C8SO4) saturated with univalent sulfate salts in the temperature range 10 degrees C-90 degrees C. This ionic liquid presents a lyotropic mesophase about room temperature when mixed with about a 20 wt% of water. The salts used are lithium, sodium and potassium sulfates, and the amount of water varies from 16 wt% to 22 wt% depending on the given mixture. As a reference, we have also prepared and characterized four aqueous IL mixtures (without salt addition) in the same water concentration range. The solubility of the different salts is scarce in the pure ILs (less than 20 x 10(-6)), while in the aqueous mixtures prepared it varies, going from 200 x 10(-6) for Na up to 700 x 10(-6) for Li. As expected, we find that with the addition of the salts, both density and viscosity increase while the ionic conductivity decreases. However, the extent of these effects depends very much on the nature of the salt and the amount of water (which also influence the solubility of the salt). The measured results are rationalized in terms of water content and salt solubility in the ternary mixtures. We observed that the transition from the liquid to the rigid-gel phases takes some temperature degrees, where the sample is in a stable quasi-gel state. Those transition temperatures, from the liquid to the quasi-gel states, and from the quasi-gel to rigid-gel states are related to the nature of the salt metal present in the mixture for samples with the same water content.
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| 3. |
- Driver, Gordon W., et al.
(författare)
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Interpretation of Fusion and Vaporisation Entropies for Various Classes of Substances, with a Focus on Salts
- 2014
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Ingår i: Journal of Chemical Thermodynamics. - : Elsevier. - 0021-9614 .- 1096-3626. ; 70:March 2014, s. 207-2013
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Tidskriftsartikel (refereegranskat)abstract
- Entropies of fusion and vaporisation of a variety of elements and compounds have been derived from literature data. Fusion entropies range from low values for metals and certain cyclic hydrocarbons (e.g. cyclopentane) through modest values for salts to high values for materials undergoing drastic rearrangement or disentanglement such as aluminium chloride and n-alkanes. Entropies of vaporisation for most substances are close to the Trouton’s Law value of ∼100 J deg.-1 mol.-1, with low values for species which associate on boiling (e.g. acetic acid) and higher values signifying simple dissociation (e.g. nitrogen tetroxide) or total decomposition (e.g. some ionic liquids). The nature of inorganic and semi-organic salts in all 3 phases is discussed.
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| 4. |
- Ge, Xinlei, et al.
(författare)
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A new three-particle-interaction model to predict the thermodynamic properties of different electrolytes
- 2007
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Ingår i: Journal of Chemical Thermodynamics. - : Elsevier BV. - 0021-9614 .- 1096-3626. ; 39:4, s. 602-612
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 5. |
- Javadian, S., et al.
(författare)
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Self-assembled nano structures of cationic ester-containing gemini surfactants: The surfactant structure and salt effects
- 2013
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Ingår i: Journal of Chemical Thermodynamics. - : Elsevier BV. - 0021-9614 .- 1096-3626. ; 62, s. 201-210
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Tidskriftsartikel (refereegranskat)abstract
- The aggregation behavior of ester-containing cationic gemini surfactants, dodecyl esterquat and dodecyl betainate geminis was investigated using tensiometry, conductometry, viscometry, dynamic light scattering (DLS), transmission electron microscopy (TEM) and optical microscopy techniques in the absence and presence of NaBr electrolyte. The effect of chemical structure (i.e. the presence of ester bond in alkyl chain and the spacer length) on physicochemical properties and morphology of the surfactants was studied. The results showed that the ester-containing gemini surfactants formed spherical aggregates at dilute concentration (1.1 %wt). At higher concentration (∼3.7 %wt) the morphology is different depending on the position of ester bond in alkyl chain and the spacer length. Dodecyl betainate gemini with short spacer (s = 2) formed gel as a result of the formation of worm-like micelles in the aqueous solution. Dodecyl betainate gemini (s = 3) formed large vesicles enclosing smaller ones and dodecyl esterquat gemini (s = 3) formed both short cylindrical and spherical micelles. The salt addition induced the growth of micelles and in the case of dodecyl betainate (s = 2) gemini changed the morphology from worm-like micelles to lamellar phase.
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| 6. |
- Ji, Xiaoyan, et al.
(författare)
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Mean activity coefficients of NaCl in (sodium chloride + sodium bicarbonate + water) fromT = (293.15 to 308.15) K
- 2001
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Ingår i: Journal of Chemical Thermodynamics. - : Elsevier BV. - 0021-9614 .- 1096-3626. ; 33, s. 1107-1119
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Tidskriftsartikel (refereegranskat)abstract
- The mean activity coefficients of NaCl in (sodium chloride + sodium bicarbonate + water) were determined experimentally in the temperature range 293.15 K to 308.15 K at four NaHCO3 molality fractions (0.1, 0.3, 0.5, and 0.7). The measurements were made with an electrochemical cell, using a Na+ glass ion-selective electrode and a Cl- solid-state ion-selective electrode. The experimental values reported by Butler and Huston are found to be higher than those calculated from the Pitzer equation using the existing parameters while the experimental results of this work are close to the calculated values, up to an NaHCO3 molality fraction of 0.5. At the NaHCO3 molality fraction of 0.7, the experimental data are much lower than the calculated values, implying that the interference of HCO3- on the Na+ glass ion-selective electrode can only be neglected up to a molality fraction of NaHCO3 of 0.5, an observation which is consistent with that of Butler and Huston.
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| 7. |
- Kocherbitov, Vitaly
(författare)
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On the calculation of thermodynamic parameters in sorption calorimetric experiments
- 2021
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Ingår i: Journal of Chemical Thermodynamics. - : Elsevier. - 0021-9614 .- 1096-3626. ; 152
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Tidskriftsartikel (refereegranskat)abstract
- The sorption calorimetry method developed by Wadso and co-workers is one of the most successful methods for studying the enthalpy of vapor sorption by solids and gels. A unique feature of this method is a simultaneous measurement of the water sorption isotherm and the sorption enthalpy. The accuracy of the enthalpy measurements in sorption calorimetric experiments can be affected by diffusion of water vapour through the injection channel tube and potentially through small leaks in the sorption cell. At high water activities this leads to an apparent drift of the measured enthalpies towards endothermic values. In this work we propose an improvement of the enthalpy calculation method, that eliminates these effects and substantially improves the accuracy of the enthalpy measurements. The new method is successfully tested on previously published sorption calorimetric data and can be recommended for use in future experiments. (C) 2020 The Author(s). Published by Elsevier Ltd.
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| 8. |
- Kuhs, Manuel, et al.
(författare)
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Thermodynamics of fenoxycarb in solution
- 2013
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Ingår i: Journal of Chemical Thermodynamics. - : Elsevier. - 0021-9614 .- 1096-3626. ; 66, s. 50-58
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 9. |
- Lindberg, Daniel, et al.
(författare)
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Thermodynamic evaluation and optimization of the (Na+K+S) system
- 2006
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Ingår i: Journal of Chemical Thermodynamics. - London : Academic Press. - 0021-9614 .- 1096-3626. ; 38:7, s. 900-915
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Tidskriftsartikel (refereegranskat)abstract
- The (Na + K + S) system is of primary importance for the combustion of black liquor in the kraft recovery boilers in pulp and paper mills. A thermodynamic evaluation and optimization for the (Na + K + S) system has been made. All available data for the system have been critically evaluated to obtain optimized parameters of thermodynamic models for all phases. The liquid model is the quasichemical model in the quadruplet approximation, which evaluates 1st- and 2nd-nearest-neighbour short-range-order. In this model, cations (Na+ and K+) are assumed to mix on a cationic sublattice, while anions (S2-, S-2(2-), S-3(2-), S-4(2-), S-5(2-), S-6(2-), S-7(2-), S-8(2-), Va(-)) are assumed to mix on an anionic sublattice. The thermodynamic data of the liquid polysulphide components M2S1+n (M = Na, K and n = 1-7) are fitted to Delta G = A(n) + B(n) . T for the reaction M2S(1) + nS(1) = M2Sn+1 (1). The solid phases are the alkali alloys, alkali sulphides, several different alkali polysulphides and sulphur. The solid solutions (Na, K), (Na, K)(2)S and (Na, K)(2)S-2 are modelled using the compound energy formalism. The models can be used to predict the thermodynamic properties and phase equilibria in the multicomponent heterogeneous system. The experimental data are reproduced within experimental error limits for equilibria between solid, liquid and gas. The ternary phase diagram of the system (Na2S + K2S + S) has been predicted as no experimental determinations of the phase diagram have been made previously.
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| 10. |
- Lindberg, Daniel, et al.
(författare)
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Thermodynamic evaluation and optimization of the (Na2CO3+Na2SO4+Na2S+K2CO3+K2SO4+K2S) system
- 2007
-
Ingår i: Journal of Chemical Thermodynamics. - London : Academic Press. - 0021-9614 .- 1096-3626. ; 39:6, s. 942-960
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Tidskriftsartikel (refereegranskat)abstract
- A critical evaluation of all phase diagram and thermodynamic data were performed for the solid and liquid phases of the (Na2CO3 + Na2SO4 + Na2S + K2CO3 + K2SO4 + K2S) system and optimized model parameters were obtained. The Modified Quasichemical Model in the Quadruplet Approximation was used for modelling the liquid phase. The model evaluates first- and second-nearest-neighbour short-range ordering, where the cations (Na+ and K+) are assumed to mix on a cationic sublattice, while anions are (CO32- ,SO42-, and S2-) are assumed to mix on an anionic sublattice. The Compound Energy Formalism was used for modelling the solid solutions of (Na, K)(2)(CO3, SO4, S). The models can be used to predict the thermodynamic properties and phase equilibria in multicomponent heterogeneous systems. The experimental data from the literature were reproduced within experimental error limits.
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| 11. |
- Lindberg, Daniel, et al.
(författare)
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Thermodynamic evaluation and optimization of the (Na2SO4+K2SO4+Na2S2O7+K2S2O7) system
- 2006
-
Ingår i: Journal of Chemical Thermodynamics. - London : Academic Press. - 0021-9614 .- 1096-3626. ; 38:12, s. 1568-1583
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Tidskriftsartikel (refereegranskat)abstract
- A complete, critical evaluation of all phase diagram and thermodynamic data was performed for all phases of the (Na2SO4 + K2SO4 + Na2S2O7 + K2S2O7) system and optimized model parameters were obtained. The Modified Quasichemical Model in the Quadruplet Approximation was used for modelling the liquid phase. The model evaluates first- and second-nearest-neighbour short-range ordering, where the cations (Na+ and K+) are assumed to mix on a cationic sublattice. The Compound Energy Formalism was used for modelling the solid Solutions of (Na,K)(2)SO4 and (Na,K)(2)S2O7. The models can be used to predict the thermodynamic properties and phase equilibria in multicomponent heterogeneous systems. The experimental data from the literature were reproduced within experimental error limits.
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| 12. |
- Lindberg, Daniel, et al.
(författare)
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Thermodynamic evaluation and optimization of the (NaCl + Na2SO4+Na2CO3+KCl+K2SO4+K2CO3) system
- 2007
-
Ingår i: Journal of Chemical Thermodynamics. - London : Academic Press. - 0021-9614 .- 1096-3626. ; 39:7, s. 1001-1021
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Tidskriftsartikel (refereegranskat)abstract
- A complete, critical evaluation of all phase diagrams and thermodynamic data was performed for all condensed phases of the (NaCl + Na2SO4 + Na2CO3 + KCl + K2SO4 + K2CO3) system, and optimized parameters for the thermodynamic solution models were obtained. The Modified Quasichemical Model in the Quadruplet Approximation was used for modelling the liquid phase. The model evaluates first- and second-nearest-neighbour short-range order, where the cations (Na+ and K+) were assumed to mix on a cationic sublattice, while anions (CO32-, SO42-, and Cl-) were assumed to mix on an anionic sublattice. The thermodynamic properties of the solid solutions of (Na,K)(2)(SO4,CO3) were modelled using the Compound Energy Formalism, and (Na,K)CI was modelled using a substitutional model in previous studies. Phase transitions in the common-cation ternary systems (NaCl + Na2SO4 + Na2CO3) and (KCl + K2SO4 + K2CO3) were studied experimentally using d.s.c./t.g.a. The experimental results were used as input for evaluating the phase equilibrium in the common-cation ternary systems. The models can be used to predict the thermodynamic properties and phase equilibria in multicomponent heterogeneous systems. The experimental data from the literature are reproduced within experimental error limits.
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| 13. |
- Lindberg, Gustav, et al.
(författare)
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Determination of thermodynamic properties of Na2S using solid-state EMF measurements
- 2007
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Ingår i: Journal of Chemical Thermodynamics. - : Elsevier. - 0021-9614 .- 1096-3626. ; 39:1, s. 44-48
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Tidskriftsartikel (refereegranskat)abstract
- To obtain reliable thermodynamic data for Na2S(s), solid-state EMF measurements of the cell Pd(s)|O2(g)|Na2S(s), Na2SO4(s)|YSZ| Fe(s), FeO(s)|O2(g)ref| Pd(s) were carried out in the temperature range 870 < T/K < 1000 with yttria stabilized zirconia as the solid electrolyte. The measured EMF values were fitted according to the equation Efit/V (±0.00047) = 0.63650 − 0.00584732(T/K) + 0.00073190(T/K) ln (T/K). From the experimental results and the available literature data on Na2SO4(s), the equilibrium constant of formation for Na2S(s) was determined to be lg Kf(Na2S(s)) (±0.05) = 216.28 − 4750(T/K)−1 − 28.28878 ln (T/K). Gibbs energy of formation for Na2S(s) was obtained as ΔfG(Na2S(s))/(kJ · mol−1) (±1.0) = 90.9 − 4.1407(T/K) + 0.5415849(T/K) ln (T/K). By applying third law analysis of the experimental data, the standard enthalpy of formation of Na2S(s) was evaluated to be ΔfH(Na2S(s), 298.15 K)/(kJ · mol−1) (±1.0) = −369.0. Using the literature data for Cp and the calculated ΔfH, the standard entropy was evaluated to S(Na2S(s), 298.15 K)/(J · mol−1 · K−1) (±2.0) = 97.0.
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| 14. |
- Lundberg, Daniel
(författare)
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Apparent molar volumes and compressibilities of lanthanum, gadolinium, lutetium and sodium trifluoromethanesulfonates in N,N-dimethylformamide and N,N-dimethylacetamide
- 2013
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Ingår i: Journal of Chemical Thermodynamics. - : Elsevier BV. - 0021-9614 .- 1096-3626. ; 58, s. 46-54
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Tidskriftsartikel (refereegranskat)abstract
- The concentration and temperature dependencies of density of lanthanum, gadolinium, lutetium and sodium trifluoromethanesulfonates in N,N-dimethylformamide (DMF) and N,N-dimethylacetamide (DMA) have been determined. From density data the apparent molar volumes and partial molar volumes of the salts at infinite dilution as well as the expansibilities have been evaluated. The apparent molar isentropic compressibilities of lanthanum, gadolinium, lutetium and sodium trifluoromethanesulfonates in DMF and DMA have been calculated from sound velocity data obtained at 298.15 K. The results have been discussed in terms of ion-solvent interactions. (c) 2012 Elsevier Ltd. All rights reserved.
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| 15. |
- Lundberg, Daniel
(författare)
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Solvation of alkaline earth metal ions in N,N-dimethylformamide and N,N-dimethylacetamide - A volumetric and acoustic study
- 2016
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Ingår i: Journal of Chemical Thermodynamics. - : Elsevier BV. - 0021-9614 .- 1096-3626. ; 92, s. 108-117
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Tidskriftsartikel (refereegranskat)abstract
- Densities and sound velocities at temperatures (298.15, 303.15, 308.15, 313.15 and 318.15) K of magnesium( II), calcium(II) and strontium(II) trifluoromethanesulfonates (triflates), as well as barium(II) perchlorate in N,N-dimethylformamide (dmf) and N,N-dimethylacetamide (dma) have been measured over the composition range studied. From these results, apparent molar volumes and apparent molar isentropic compressibilities at infinite dilution, as well as expansibilities have been evaluated. The results have been discussed in terms of ion-solvent interactions and coordination number. (C) 2015 Elsevier Ltd. All rights reserved.
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| 16. |
- Löfström Engdahl, Elin, 1983, et al.
(författare)
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Extraction thermodynamics of Am(III) and Eu(III) using CyMe4-BTBP in various organic diluents
- 2014
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Ingår i: Journal of Chemical Thermodynamics. - : Elsevier BV. - 0021-9614 .- 1096-3626. ; 76, s. 64-69
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Tidskriftsartikel (refereegranskat)abstract
- The thermodynamic parameters (ln KEx, ΔH0 and ΔS0) for the extractions of americium and europium using CyMe4-BTBP in three various diluents (cyclohexanone, hexanol and nitrobenzene) have been studied. The stoichiometry of the complexes was obtained by slope analysis of the distribution ratios of the metals as a function of the ligand concentration. The influence on temperature on the americium/europium separation was investigated for process development causes.In cyclohexanone it was shown that the stability of the (1:2) complex is stronger in the americium case than in the europium case where the (1:1) seems to dominate. Similarly; the 1:2 complex are more dominant in the case of americium compared to in the europium complex in hexanol as well. In nitrobenzene both the metals form 1:1 complexes. The extractions of both the nuclides in the three diluents are exothermic. However, since the europium complexes in hexanol and cyclohexanone were shown to contain both 1:1 and 1:2 complexes no further evaluation of those two systems in particular could be made. The enthalpy for the nitrobenzene system differs radically compared to the two others, having a more prominent decrease in ΔH 0 (for example View the MathML source = −44 ± 6.2 (kJ · mol−1) in nitrobenzene compared to View the MathML source = −19 ± 1.1 (kJ · mol−1) in hexanol). In the entropies of the system no differences is seen when comparing the diluents cyclohexanone and hexanol, however, there is a difference in ΔS0 between the two and nitrobenzene, were the change in entropy is negative in the nitrobenzene system and positive in the other two diluents.In addition, it was shown that the temperature affected the separation factor of americium from europium. The separation factors decreases in all the three systems as the temperature increases. This is of importance during process development purposes.
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| 17. |
- Ma, Chunyan, et al.
(författare)
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Molar enthalpy of mixing and refractive indices of choline chloride-based deep eutectic solvents with water
- 2017
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Ingår i: Journal of Chemical Thermodynamics. - : Elsevier. - 0021-9614 .- 1096-3626. ; 105, s. 30-36
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Tidskriftsartikel (refereegranskat)abstract
- The molar enthalpies of mixing were measured for binary systems of choline chloride-based deep eutectic solvents (glycerol, ethylene glycol and malonic acid) with water at 298.15 K and 308.15 K, and atmospheric pressure with an isothermal calorimeter. Refractive indices were also measured at 303.15 K and atmospheric pressure. The binary mixtures of {chcl/glycerol (1:2) + water, chcl/ethylene glycol (1:2) + water} showed exothermic behaviour over the entire range of composition, while the binary mixture of {chcl/malonic acid (1:1) + water} showed endothermic behaviour at first and then changed to be exothermic with the increasing content of chcl/malonic acid (1:1). Experimental refractive indices were fitted with the Redlich–Kister equation, and experimental molar enthalpies of mixing were correlated with the Redlich–Kister equation and the non-random two-liquid (NRTL) model. The NRTL model with the fitted parameters was used to predict the vapour pressures of these three mixtures. For mixtures of {chcl/glycerol (1:2) + water} and {chcl/ethylene glycol (1:2) + water}, the predicted vapour pressures agreed well with the experimental reults from the literature. While for mixture of {chcl/malonic acid (1:1)+water}, the predicted vapour pressures showed deviation at the high concentration of chcl/malonic acid (1:1), and this was probably because of the complex molecular interaction between chcl/malonic acid (1:1) and water
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| 18. |
- Matyskin, Artem, 1989, et al.
(författare)
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Weak barium and radium hydrolysis using an ion exchange method and its uncertainty assessment
- 2019
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Ingår i: Journal of Chemical Thermodynamics. - : Elsevier BV. - 0021-9614 .- 1096-3626. ; 128, s. 362-371
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Tidskriftsartikel (refereegranskat)abstract
- The hydrolysis of Ba2+and Ra2+was studied at 25 °C in aqueous mixtures of NaOH and NaClO4using an ion exchange method and radiotracer and batch techniques. The distribution of133Ba and226Ra between solid (ion exchange resin) and aqueous (mixture of NaOH and NaClO4) phases was measured via gamma spectrometry and liquid scintillation counting. The total ionic strength was kept constant and the concentration of NaOH in the aqueous phase was varied from 0 (pure NaClO4) to pure NaOH from sample to sample. It was shown that an increase of the Ba2+or Ra2+concentration in the aqueous phase with an increase of the NaOH concentration cannot be explained solely by Ba2+or Ra2+activity coefficient differences in the NaOH and NaClO4media (salting out) and that weak BaOH+and RaOH+ion pairing occurs in the systems studied. A model for weak ion association was developed and apparent BaOH+and RaOH+stability constants were derived assuming the formation of weak aqueous NaOH(aq) ion pairs via non-linear curve fitting. It was demonstrated that systematic uncertainties have a much greater contribution to the NaOH(aq), BaOH+and RaOH+stability constant uncertainty budget compared to stochastic uncertainties and a method for estimation of the systematic uncertainties was proposed. The method combines fitting, restricted primitive model computations with surveyed literature data that resulted in a stability constant for NaOH(aq) that ranged from 0 to 1 at ionic strengths below 5 mol·kg−1(i.e. KNaOH= 0.5 ± 0.5, where the uncertainty is a systematic 95% confidence interval). The variation of KNaOHallowed the estimation of the systematic 95% confidence interval in the apparent stability constants of BaOH+and RaOH+. The specific ion interaction theory was used to extrapolate the derived logarithms of the BaOH+and RaOH+apparent stability constants to zero ionic strength (log10K = 0.7 ± 0.2 for both ion pairs) and obtain the relevant ion interaction parameters. It was shown that both the Ba2+and Ra2+ions have similar activity coefficients and undergo similar short-range interactions in aqueous NaOH-NaClO4media.
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| 19. |
- Nordström, Fredrik, et al.
(författare)
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Determination of the activity of a molecular solute in saturated solution
- 2008
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Ingår i: Journal of Chemical Thermodynamics. - : Elsevier BV. - 0021-9614 .- 1096-3626. ; 40:12, s. 1684-1692
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 20. |
- Runnsjö, Anna, et al.
(författare)
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Semifluorinated alkanes and alkanes : a phase study of the perfluorohexyloctane - tetradecane system
- 2017
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Ingår i: Journal of Chemical Thermodynamics. - : Elsevier. - 0021-9614 .- 1096-3626. ; 105, s. 352-361
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Tidskriftsartikel (refereegranskat)abstract
- The binary system perfluorohexyloctane (F6H8)–tetradecane (C14) was investigated in order to increase understanding of interactions of semifluorinated alkanes (SFAs) with hydrophobic molecules. The thermal phase behavior for F6H8 and C14 and their mixtures was determined using DSC. The activity coefficients for both components in the mixtures were calculated and Gibbs energy of mixing was determined. Furthermore, enthalpies of mixing were determined with ITC and structural investigations of the solid and the liquid phases were performed with SAXS and SWAXD. It was found that F6H8 displays one solid-solid transition at −42.3 °C (ΔH = 1.1 kJ/mol) and one solid-liquid transition at −5.9 °C (ΔH = 16.6 kJ/mol). Due to the low enthalpy of the solid-liquid transition it is likely that F6H8 is not fully crystallized in the solid phase but partly amorphous. The F6H8–C14 system displays a eutectic phase behavior and the liquid mixtures display a positive deviation from ideal mixing. C14 crystalizes in a triclinic unit cell as shown before, whereas crystallization of F6H8 in a lamellar rippled phase is shown for the first time. This ripple phase comprises a bilayer of tilted alternating heavily interdigitated F6H8 molecules in an oblique subunit cell.
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| 21. |
- Sandström, Malin, et al.
(författare)
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Determination of standard Gibbs energy of formation for CaKPO4, CaK4(PO4)2, CaK2P2O7 and Ca10K(PO4)7 from solid state EMF measurements using yttria stabilised zirconia as solid electrolyte
- 2008
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Ingår i: Journal of Chemical Thermodynamics. - : Elsevier Ltd.. - 0021-9614 .- 1096-3626. ; 40:1, s. 40-46
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Tidskriftsartikel (refereegranskat)abstract
- The equilibrium reactions: 4CaKPO4(s) + 6Ni(s) CaK4(PO4)2(s) + 3CaO + 2Ni3P(s) + 5/2O2(g), 4CaKPO4(s) + 3K4P2O7(s) + 6Ni(s) 4CaK4(PO4)2(s) + 2Ni3P(s) + 5/2O2(g), 4CaK2P2O7(s) + 6Ni(s) 4CaKPO4(s) + K4P2O7(s) + 2Ni3P(s) + 5/2O2(g) and Ca10K(PO4)7(s) + 9CaK2P2O7(s) + 18Ni(s) 19CaKPO4(s) + 6Ni3P(s) + 15/2O2(g) were studied in the temperature range from 880 to 1125 K. The oxygen equilibrium pressures were determined using galvanic cells incorporating yttria stabilised zirconia as solid electrolyte. From the measured data and using literature values of standard Gibbs free energy of formation for CaO, Ni3P and K4P2O7, the following relationship of the standard Gibbs free energy of formation for CaKPO4, CaK4(PO4)2, CaK2P2O7, and Ca10K(PO4)7 were calculated: ΔfG(CaKPO4) ± 5.2/(kJ · mol−1) = −1506.6 − 3.2933(T/K) + 0.4603(T/K) · ln(T/K) 890 < (T/K) < 1125 ΔfG(CaK4(PO4)2) ± 8.9/(kJ · mol−1) = −3498.2 − 2.1339(T/K) + 0.3661(T/K) · ln(T/K) 930 < (T/K) < 1125 ΔfG(CaK2P2O7) ± 7.2/(kJ · mol−1) = −2690.0 − 3.7820(T/K) + 0.5599(T/K) · ln(T/K) 940 < (T/K) < 1100 ΔfG(Ca10K(PO4)7) ± 133/(kJ · mol−1) = −5988.3 − 57.063(T/K) + 7.4407(T/K) · ln(T/K) 880 < (T/K) < 1015.
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| 22. |
- Sandström, Malin Hannah, et al.
(författare)
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Determination of standard Gibbs free energy of formation for Ca2P2O7 and Ca(PO3)2 from solid state EMF measurements using yttria stabilised zirconia as solid electrolyte
- 2006
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Ingår i: Journal of Chemical Thermodynamics. - : Elsevier BV. - 0021-9614 .- 1096-3626. ; 38:11, s. 1371-1376
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Tidskriftsartikel (refereegranskat)abstract
- The equilibrium reactions: 3Ca2P2O7(s) + 6Ni(s) reversible arrow 2Ca3(PO4)2(s) + 2Ni3P(s) + 5/O-2(g) and 2Ca(PO3)2(s) + 6Ni(s) reversible arrow Ca2P2O7(s) + 2Ni3P(s) +/- 5/2O2(g) were studied in the temperature range 890 K to 1140 K. The oxygen equilibrium pressures were determined using galvanic cells incorporating yttria stabilized zirconia as solid electrolyte. From the measured data and using the literature values of standard Gibbs free energy of formation for Ca3(PO4)2 and Ni3P, the following relationship of the standard Gibbs free energy of formation for Ca2P2O7 and Ca(PO3)(2) were calculated: ΔfG° (Ca2P2O7) +/- 11/(kJ · mol-1)=-3475.9 + 1.5441 (T/K) -0.1051 (T/K) · 1n(T/K) and ΔfG° (Ca(PO3)2) +/- 12/(kJ · mol-1)= -3334.8 + 6.1561 (T/K) -0.6950(T/K) · 1n(T/K).
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| 23. |
- Smith, A. L., et al.
(författare)
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Thermodynamic assessment of the neptunium-oxygen system : Mass spectrometric studies and thermodynamic modelling
- 2016
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Ingår i: Journal of Chemical Thermodynamics. - : Elsevier. - 0021-9614 .- 1096-3626. ; 103, s. 257-275
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 24. |
- Svärd, Michael, et al.
(författare)
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(Solid + liquid) solubility of organic compounds in organic solvents : correlation and extrapolation
- 2014
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Ingår i: Journal of Chemical Thermodynamics. - : Elsevier. - 0021-9614 .- 1096-3626. ; 76, s. 124-133
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 25. |
- Trybula, Marcela E., et al.
(författare)
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Thermodynamics of liquid Li-Sb alloys - Experiment vs modeling
- 2019
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Ingår i: Journal of Chemical Thermodynamics. - : Academic Press. - 0021-9614 .- 1096-3626. ; 128, s. 134-140
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Tidskriftsartikel (refereegranskat)abstract
- Thermodynamic properties of liquid Li-Sb alloys have been studied both experimentally and theoretically. Electromotive force measurements (EMF) in the Li-Sb system were performed over broad range of temperature and lithium concentrations. It was found that in liquid Sb-rich alloys (x(Sb) >= 0.85) the EMF increases with increasing temperature as opposite to liquid alloys of lower Sb content (0.4 <= xSb < 0.85). Based on the present experiment results and literature data a new thermodynamic description of the liquid Li-Sb phase was developed using associate and sub-regular models. Very good agreement between experiment and new modeling data using associate model are observed. Importance of Li3Sb intermetallic compound has been tested and proved in order to have a proper description of thermodynamic and structural properties of Li-Sb liquid alloys by comparing sub-regular with associate model data. Chemistry of short-range atom ordering has been qualified and quantified at whole Sb concentration range by using Bhatia-Thornton formalism and Warren-Cowley parameter, respectively. Significant degree of chemical ordering at Li-rich alloys has been found resulted from Li3Sb compound existence in comparison to its depletion at Sb-side where liquid Li-Sb alloys display the tendency to random atoms ordering.
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| 26. |
- Tyumentsev, Mikhail S, 1988, et al.
(författare)
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Temperature effect on the distribution of lanthanides(III) in the perchlorate-malonamide-methyl isobutyl ketone systems
- 2019
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Ingår i: Journal of Chemical Thermodynamics. - : Elsevier BV. - 0021-9614 .- 1096-3626. ; 131, s. 133-148
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Tidskriftsartikel (refereegranskat)abstract
- © 2018 Elsevier Ltd Distribution ratios of trivalent lanthanide ions in extraction reactions may be affected by the denticity of a solvent extraction ligand for entropic reasons. This hypothesis was tested by studying the reactions of extraction of the lanthanides(III) (La, Nd, Eu, Dy, Er and Yb) from perchlorate media into methyl isobutyl ketone (MIBK) with three structurally related malonamide ligands (I – III): 2,2′-[1,2-phenylenebis(methylene)]bis(N,N,N’,N’-tetrabutylmalonamide) (I), 2,2′-[1,4-phenylenebis(methylene)]bis(N,N,N’,N’-tetrabutylmalonamide) (II), and 2-benzyl-N,N,N’,N’-tetrabutylmalonamide (III), the molecules of which contain either two (III) or four (I and II) carbonyl oxygen donor atoms. Ligands I and II are the structural isomers. The extracted species in the reactions with all these ligands have the (1:2) metal-to-ligand stoichiometric ratios. All the extraction reactions are enthalpy-driven and have negative values of the standard molar entropy changes at T = (298–313) K. Since the least exothermic standard molar enthalpy changes of the extraction reactions (ΔrH°T) and the least negative standard molar entropy changes of the reactions (ΔrS°T) were observed for ligand I, it was concluded, that the distribution ratios of the lanthanide(III) ions were the highest in the reactions with I due to the entropic effect, presumably resulting from the difference in the coordination of the extraction ligands with the lanthanide(III) ions.
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| 27. |
- Yang, Huaiyu, et al.
(författare)
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Thermodynamics of molecular solids in organic solvents
- 2012
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Ingår i: Journal of Chemical Thermodynamics. - : Elsevier BV. - 0021-9614 .- 1096-3626. ; 48, s. 150-159
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Tidskriftsartikel (refereegranskat)abstract
- 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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| 28. |
- Zafarani-Moattar, Mohammed Taghi, et al.
(författare)
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Apparent molar volumes, apparent isentropic compressibilities, and viscosity B-coefficients of 1-ethyl-3- methylimidazolium bromide in aqueous di-potassium hydrogen phosphate and potassium di-hydrogen phosphate solutions at T = (298.15, 303.15, 308.15, 313.15, and 318.15) K
- 2012
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Ingår i: Journal of Chemical Thermodynamics. - : Elsevier. - 0021-9614 .- 1096-3626. ; 54, s. 192-203
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Tidskriftsartikel (refereegranskat)abstract
- Apparent molar volumes Vϕ, apparent isentropic compressibilities κϕ, and viscosity B-coefficients for 1-ethyl-3-methylimidazolium bromide (EmimBr) in aqueous di-potassium hydrogen phosphate (K2HPO4) solutions with salt weight fractions (ws = 0.00, 0.10, 0.15, and 0.20) and potassium di-hydrogen phosphate (KH2PO4) solutions with salt weight fractions (ws = 0.00, 0.04, 0.07, and 0.10) have been determined from solution density, sound velocity and viscosity measurements at temperatures over the range (298.15 to 318.15) K as function of concentration of 1-ethyl-3-methylimidazolium bromide (EmimBr). In the investigated temperature range, the relation: Vϕ0=a0+a1T+a2T2, has been used to describe the temperature dependence of the standard partial molar volumes Vϕ0. These results have, in conjunction with the results obtained in pure water, been used to deduce the standard volumes of transfer ΔVϕ0 and viscosity B-coefficients of transfer for 1-ethyl-3-methylimidazolium bromide from water to aqueous K2HPO4 and KH2PO4 solutions for rationalizing various interactions in the ternary solutions. The structure making or breaking ability of 1-ethyl-3-methylimidazolium bromide has been discussed in terms of the sign of ∂2Vϕ0∂T2. An increase in the transfer volume of 1-ethyl-3-methylimidazolium bromide with increasing phosphate salts concentration has been explained by Friedman–Krishnan co-sphere model. The activation parameters of viscous flow for the ternary solutions investigated were also determined and discussed by the application of transition state theory.
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| 29. |
- Zafarani-Moattar, Mohammed Taghi, et al.
(författare)
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Effect of tri-potassium phosphate on volumetric, acoustic, and transport behaviour of aqueous solutions of 1-ethyl-3-methylimidazolium bromide at T = (298.15 to 318.15) K
- 2010
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Ingår i: Journal of Chemical Thermodynamics. - : Elsevier. - 0021-9614 .- 1096-3626. ; 42:10, s. 1213-1221
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Tidskriftsartikel (refereegranskat)abstract
- Density, sound velocity, and viscosity of 1-ethyl-3-methylimidazolium bromide, [Emim][Br], in aqueous solutions of tri-potassium phosphate with salt weight fractions (ws = 0.00, 0.10, 0.15, and 0.20) have been measured as a function of concentration of [Emim][Br] at atmospheric pressure and T = (298.15, 303.15, 308.15, 313.15, and 318.15) K. The apparent molar volume, isentropic compressibility, apparent isentropic compressibility, and relative viscosity values have been evaluated from the experimental data. The partial molar volume and isentropic compressibility at infinite dilution, and viscosity B-coefficient obtained from these data have been used to calculate the corresponding transfer parameters for the studied IL from water to the aqueous tri-potassium phosphate solutions. Also, an empirical equation was satisfactorily used to correlate the experimental viscosity data.
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| 30. |
- Zafarani-Moattar, Mohammed Taghi, et al.
(författare)
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Measurement and modeling of densities and sound velocities of the systems poly(propylene glycol) + methanol, +ethanol, +1-propanol, +2-propanol and +1-butanol at T = 298.15 K
- 2006
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Ingår i: Journal of Chemical Thermodynamics. - : Elsevier. - 0021-9614 .- 1096-3626. ; 38:3, s. 257-263
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Tidskriftsartikel (refereegranskat)abstract
- Experiments have been performed at T = 298.15 K to measure the density and sound velocity of the systems {poly(propylene glycol) + methanol, +ethanol, +1-propanol, 2-propanol and +1-butanol} over the whole range of composition. From these measurements, values of the excess molar volume (Vmex)">(Vmex) and excess molar isentropic compression, Ks,mex">Ks,mex , equal to -(∂Vmex/∂p)s">-(∂Vmex/∂p)s were calculated. The excess molar volume for all of these systems were found to be negative and decreases in magnitude as size of alcohol increases, except for 2-propanol solutions for which the magnitude of the excess volume is higher than that of 1-butanol solutions. Expressions for VmexandKs,mex">VmexandKs,mex of polymer solutions were obtained for the model of Flory–Huggins and the polymer non-random two liquid (NRTL) model. These expressions were used to fit the experimental VmexandKs,mex">VmexandKs,mex data of the investigated systems.
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