Molar Enthalpies Of Solution Research Articles

Effect of BaO, Basicity and Temperature on Manganese Distribution between Slag and Hot Metal in Blast Furnace

Daily average data obtained on the 1033 m3 blast furnace No.3 of the Egyptian Iron and Steel Company (EISCO) were used to investigate the effects of BaO, basicity and temperature on the activity coefficient and activity of MnO in the slag as well as on the manganate capacity and manganese distribution between slag and metal. The activity coefficient was estimated by using the regular ionic solution model. Both activity coefficient and activity increase with increasing basicity and BaO content of the slag. The activity, manganate capacity and manganese distribution ratio are largely dependent on temperature and change only slightly with the basicity. The relative partial molar enthalpy of solution of MnO in the slag is 107 kJ/mol. The relationship between activity and concentration of MnO in the slag is linear over the whole ranges of temperature (1400 to 1450°C) and basicity, (CaO/SiO2 = 0.61-0.95). The concentration dependence of manganese activity in hot metal is also linear and the activity coefficient of Mn in hot metal is 0.51. The distribution ratios calculated by using the concept of manganate capacity were correlated with the relevant values obtained from the slag and metal analyses. The calculated partition ratios are in agreement with the observed values. In all cases, empirical equations have been derived.

Enthalpy of Solution of the Amino Acid Ionic Liquid 1-Butyl-3-methylimidazolium Glutamine

The molar enthalpies of solution, ΔsolHm(wc), of a new amino acid ionic liquid 1-butyl-3-methylimidazolium glutamine [Bmim][Glu], containing various amounts of water and with various aqueous molalities, were measured with a solution-reaction isoperibol calorimeter at (298.15 ± 0.01) K, where wc denotes water content. The standard molar enthalpies of solution of [Bmim][Glu] with given amounts of water, ΔsolH0m(wc), were obtained according to Archer’s method. To eliminate the effect of the small amount of water in [Bmim][Glu], a linear fitting of ΔsolH0m(wc) versus the water content was carried out, and the intercept, ΔsolH0m (pure ionic liquid) = −(40.55 ± 0.06) kJ·mol−1, is the standard molar enthalpy of solution of anhydrous [Bmim][Glu]. Furthermore, the Glasser’s theory of lattice energy was used to estimate the hydration enthalpy of glutamine anion [Glu]−.

Thermodynamics of Sodium 5-Nitroisophthalic Acid Monohydrate

Low-temperature heat capacities of sodium 5-nitroisophthalic acid monohydrate (C8O6NH3Na2·H2O, s) were measured by a precision automated adiabatic calorimeter over the temperature range from (78 to 398) K. The experimental values of the molar heat capacities were fitted to a polynomial equation of heat capacities (Cp,m) with the reduced temperatures (X), [X = f(T)], by a least-squares method. The smoothed molar heat capacities and thermodynamic functions of the compound (C8O6NH3Na2·H2O, s) were calculated on the basis of the fitted polynomial. The constant volume energy of combustion of the compound at T = 298.15 K was measured by a precise rotating-bomb combustion calorimeter to be ΔcU = −(3969.41 ± 1.74) kJ·mol−1. The standard molar enthalpy of combustion of the compound was determined to be ΔcHθm = −(3965.07 ± 1.74) kJ·mol−1. The standard molar enthalpy of formation of the compound was calculated to be ΔfHθm (C8O6NH3Na2·H2O, s) = −(408.45 ± 2.03) kJ·mol−1 in accordance with Hess’s law. The standard molar enthalpy of solution of the compound, ΔsolHθm (C8O6NH3Na2·H2O, s), has been determined as (22.133 ± 0.111) kJ·mol−1. The standard molar enthalpy of the hydrated anion of the compound was determined as ΔfHθm (C8O6NH32−, aq) = (380.11 ± 2.04) kJ·mol−1, from the standard molar enthalpy of solution and other auxiliary thermodynamic data through a thermochemical cycle. The thermostability of the compound was investigated by thermogravimetric/differential thermogravimetric/differential scanning calorimetry (TG-DTG-DSC).

Solubility of CF 4 in lower alcohols

This work is inserted in a research program that consists mainly in the experimental and theoretical study of the effect of association/solvation between solute and solvent molecules in the solubility of gases in liquids. The solubilities of tetrafluoromethane in lower alcohols (methanol, ethanol, 1-propanol, 1-butanol) have been determined in the temperature range of 288–308 K, at atmospheric pressure, using an automated apparatus recently assembled in our laboratory. An accuracy of 0.6% and a precision of the same order of magnitude was achieved. The solubility is the lowest in methanol which is the highest associated alcohol and increases with the C-content of the alcohol. The molar Gibbs energy, enthalpy and entropy of solution were calculated from the experimental results (at 1 atm partial pressure of the gas and 298 K). A semiempirical correlation between the solubility of CF 4 in alcohols at 298 K and the Gutmann acceptor number (AN) of the solvents has been developed.

A calorimetric unit for measurements of the thermal effects of reactions in solution

A calorimetric unit for measurements of the thermal effects of reactions in solution was created. The unit was designed following the classic scheme of a hermetic liquid calorimeter working under isoperibolic conditions, it had a thermometric sensitivity of 10−4 K and a calorimetric sensitivity of 10−2 J. The accuracy of calorimeter operation was checked against the heats of solution of potassium chloride. The molar integral enthalpies of solution of glycine in water at 298 K were determined.

Calorimetric studies of interactions of some peptides with electrolytes, urea and ethanol in water at 298.15 K

The standard molar enthalpies of solution at infinite dilution \( \Updelta_{\text{sol}} H_{\text{m}}^{\infty } \) of glycylglycine, dl-alanyl-dl-alanine and glycylglycylglycine in aqueous solutions of potassium chloride and ethanol as well as of glycylglycine and glycylglycylglycine in the solutions containing urea and water have been determined by calorimetry at the temperature 298.15 K. Changes of solution enthalpy, expressed in a form so-called heterotactic interaction coefficients, \( h_{\text{xy}} \) were used for analysis of interactions occurring between the investigated solutes in water. The group contributions illustrating the interactions of KCl, urea and ethanol with selected functional groups in the peptide molecules, namely CH2, “pep,” and “ion” groups, were calculated and discussed.

The Enthalpy of Solution of the Alanine-Based Ionic Liquid [C4mim][Ala

The molar enthalpies of solution of an alanine-based ionic liquid (IL) [C4mim][Ala], 1-butyl-3-methylimidazolium alanine, containing various amount of water and various molalities ΔsolHm(wc), were measured with a solution-reaction isoperibol calorimeter at (298.15±0.01) K, where wc denotes water content. According to Archer’s method, the standard molar enthalpies of solution of [C4mim][Ala] containing known amounts of water, \(\Delta_{\mathrm{sol}}H_{\mathrm{m}}^{\mathrm{o}}(\mathrm{wc})\) , were obtained. In order to eliminate the effect of the small amount of residual water in the source [C4mim][Ala], a linear fitting of \(\Delta_{\mathrm{sol}}H_{\mathrm{m}}^{\mathrm{o}}(\mathrm{wc})\) against water content was carried out, yielding a good straight line where the intercept is the standard molar enthalpy of solution of anhydrous [C4mim][Ala], \(\Delta_{\mathrm{sol}}H_{\mathrm{m}}^{\mathrm{o}}(\mathrm{pure}\ \mathrm{IL})=-(61.42\pm 0.08)\) kJ⋅mol−1. The hydration enthalpy of the alanine anion [Ala]− was estimated using Glasser’s lattice energy theory.

Enthalpy of Dilution of Aqueous [C4mim][Gly] at 298.15 K

A novel amino acid ionic liquid [C4mim][Gly] (1-butyl-3-methylimidazolium glycine) was prepared by a neutralization method. The molar enthalpies of dilution, ΔDHm(mi→mf), of aqueous [C4mim][Gly] at various molalities were measured at (298.15 ± 0.01) K. The values of the apparent relative molar enthalpy, φL, were calculated by using both the extended Debye−Huckel equation and the Pitzer equation, which were in good agreement within experimental error. In terms of φL, the molar enthalpies of solution of [C4mim][Gly], ΔsHm, at various molalities were estimated. The estimated values of ΔsHm were consistent with the experimental values previously obtained.

Mass-Fraction Activity Coefficients at Infinite Dilution Measurements for Organic Solutes and Water in the Hyperbranched Polymer Boltorn W3000 Using Inverse Gas Chromatography

Thermodynamic properties of hyperbranched polymer, Boltorn BW3000, were investigated by inverse chromatography with 42 different solvents: alkanes (C5−C10), cycloalkanes (C5−C8), alkenes (C5−C8), alkynes (C5−C8), aromatic hydrocarbons (benzene, toluene, ethylbenzene, o-, m-, p-xylene, thiophene), alcohols (C1−C5) and water, ethers (diethyl-, di-n-propyl-, di-n-butylether, methyl-tert-butylether, MTBE, tetrahydrofuran, THF), and ketones (propanone, 2-pentanone, 3-pentanone, 2-hexanone, 3-hexanone, cyclopentanone) at the temperatures ranging from (308.15 to 348.15) K. The density and thermophysical properties of polymer were described. The specific retention volume (Vg), the mass-fraction activity coefficient at infinite dilution (Ω13∞), the Flory−Huggins parameter (χ13∞), the molar enthalpy of solute’s absorption in the polymer (ΔsH), the partial molar excess enthalpy at infinite dilution (ΔH1E,∞), the partial molar Gibbs excess energy at infinite dilution (ΔG1E,∞), and the solubility parameter of the poly...

Hydrophobic−Hydrophilic Solvation of Variously Substituted N-Alkylureas in Aqueous Solution: A Calorimetric Study at a Temperature of 298.15 K

Enthalpies of solution, ΔsolHm, in water, of some di-, tri-, and tetra-substituted N-alkylureas were measured by isothermal calorimetry at T = (296.84, 306.89, and 316.95) K. The molar enthalpies of solution at infinite dilution (i.d.), ΔsolHm∞, and molar heat capacity changes for the solution process at i.d., ΔsolCp,m∞, were obtained at T = 298.15 K. Molar enthalpies of solvation, ΔsolvHm∞, and partial molar heat capacities, Cp,2∞, at i.d. were then calculated from the molar enthalpies of sublimation or vaporization and molar heat capacities, Cp,m, of pure compounds in solid or liquid states, respectively. The methylene group contributions to the enthalpy of solvation was −3.7 kJ·mol−1 for di- and tri-N-alkylureas and −3.2 kJ·mol−1 for tetra-N-alkyureas, whereas the contribution to partial molar heat capacity was 91 J·K−1·mol−1 and 93 J·K−1·mol−1, respectively, in very good agreement with our earlier data for monosubstituted N-alkylureas and the literature data for various homologous series of alkyl-substituted compounds. Contributions of the functional groups of N-alkylureas were derived and compared with our earlier data for mono-N-alkylureas.

Molar Enthalpy of Solution of a Gas in Polymer near Glass Transition Point

Molar Enthalpy of Solution of a Gas in Polymer near Glass Transition Point

Phase equilibrium system of RbCl-PrCl3-HCl(12.86 mass %)-H2O at 298.15 K and standard molar enthalpy of formation of new solid-phase compound

The equilibrium solubility of the quaternary system RbCl-PrCl3-HCl-H2O was determined at 298.15 K and the corresponding equilibrium diagram was constructed in this paper. The quaternary system is complicated with three equilibrium solid phases, RbCl, RbPrCl4 · 4H2O (1:1 type) and PrCl3 · 6H2O, of which the new compound RbPrCl4 · 4H2O was found to be congruently soluble in the system. The new compound obtained was identified and characterized by the methods of X-ray diffraction, thermogravimetry, and differential thermogravimetry. The compound loses its crystal water by one step at 343 K to 453 K. The standard molar enthalpy of solution of RbPrCl4 · 4H2O in deionized water was measured to be −24.53 ± 0.22 kJ mol−1 by heat conduction microcalorimetry. Its standard molar enthalpy of formation was calculated to be −2743.20 ± 1.09 kJ mol−1.

Investigation on the Equilibrium Phase Diagram of the Ternary System TmCl3−CdCl2−H2O at 298.15 K and Standard Molar Enthalpy of Formation of Cd3TmCl9·15H2O

Equilibrium phase relation and solubility data for the rare earth trichloride TmCl3·6H2O and cadmium chloride in aqueous media were investigated. The corresponding equilibrium phase diagram in the ternary system TmCl3−CdCl2−H2O at 298.15 K was constructed. The results showed that the system was complicated and consisted of four stable equilibrium solid phases [CdCl2·2.5H2O, CdCl2·H2O, Cd3TmCl9·15H2O (3:1 type), TmCl3·6H2O]. The new compound Cd3TmCl9·15H2O was found to be congruently soluble in the system. The 3:1 type compound obtained was identified and characterized by the method of X-ray diffraction, X-ray diffraction single-crystal structure analysis, thermogravimetry, and differential thermogravimetry (TG, DTG). It belongs to a monoclinic system, with space group P2(1)/n, a = 1.2267(4) nm, b = 2.0034(7) nm, c = 1.2321(4) nm, β = 113.793(5)°, V = 2.7706(17) nm3, Dc = 2.554 g·cm−3, Z = 4. The standard molar enthalpy of solution of Cd3TmCl9·15H2O in deionized water was measured to be (29.73 ± 0.40) kJ·mol−1 by heat conduction microcalorimetry. Its standard molar enthalpy of formation was calculated to be −(6747.2 ± 1.2) kJ·mol−1.

D 2O–H 2O solvent isotope effects on the volumetric properties of aqueous 1,3-dimethyl-2-imidazolidinone between (278.15 and 318.15) K

Densities of dilute solutions of 1,3-dimethyl-2-imiazolidinone in H 2O and D 2O, with the solute mole-fractions ranging up to 0.01, have been measured with an error of 1.5 · 10 −5 g · cm −3 at (278.15, 288.15, 298.15, 308.15, 313.15, and 318.15) K and atmospheric pressure using a vibrating-tube densimeter. The partial molar volumes of the dissolved DMI (down to the infinite dilution) and solvent (H 2O or D 2O) as well as the excess molar volumes of the isotopically distinguishable solutions have been calculated. The effects of the solvent isotope substitution, solute concentration and temperature on the volume changes caused by DMI hydration have been considered. The obvious relationship between the D 2O–H 2O solvent isotope effects on the partial molar volume and enthalpy of solution of DMI has been discovered.

Thermodynamic properties of solvation of aromatic compounds in cyclohexane, heptane, benzene, 1,4-dioxane, and chloroform at 298.15 K

In order to investigate the solvation behavior of polycyclic aromatic compounds in cyclohexane and heptane, molar enthalpies of solution, Δ soln H m , densities, and sound velocities have been measured for dilute mixtures. And to make the difference in solvation thermodynamic properties between cata-condensed and polyphenyl aromatic compounds clear, the measurements of these properties were carried out for polyphenyl compounds with some aprotic solvents. Molar enthalpies of solvation, Δ solv H m , apparent partial molar volumes at infinite dilution, V m , 1 ∞ , and apparent partial molar isentropic compressions at infinite dilution, K s , m , 1 ∞ , were calculated from the measured thermodynamic quantities. The aromatic compounds investigated were benzene, naphthalene, phenanthrene, biphenyl, and o-, m-, and p-terphenyl. Solvents studied were cyclohexane, heptane, benzene, 1,4-dioxane, and chloroform. The values of Δ soln H m for the polyphenyl compounds were endothermic for all the solvents. The values of V m , 1 ∞ of the polycyclic aromatic compounds in cyclohexane were relatively larger than those in benzene, 1,4-dioxane and chloroform measured in the previous work [M. Ohba, T. Takigawa, H. Ogawa, S. Murakami, Fluid Phase Equilib. 136 (1997) 289–297]. It was found that the values of Δ solv H m , V m , 1 ∞ and K s , m , 1 ∞ depend linearly on the number of carbon atoms in the solute molecule, except for those of o- and p-terphenyl. This supports the group contribution principle. Δ solv H m per carbon atom for cata-condensed matter shows an absolute value that is almost the same as that shown by Δ solv H m per carbon atom for polyphenyl one. The value of V m , 1 ∞ per carbon atom is slightly larger for polyphenyl matter than for cata-condensed one. Solvation behavior of the polycyclic aromatic compound molecule in each of the solvent molecules was characterized by plots of the partial isentropic compressibility, κ s , 1 ∞ , against the cohesive energy density at infinite dilution, ε ∞. The strength of solvation of the polycyclic aromatic compound in a non-polar solvent is not larger than that in a polar one.

Thermodynamic characterization of poly (caprolactonediol) by inverse gas chromatography

Specific retention volumes, V 0 , were determined for 21 solute probes on poly (caprolactonediol) (PCLD) in the temperature range 323.15–403.15 K by inverse gas chromatography. The retention diagrams drawn between ln V 0 versus 1/T are linear for all the solutes since PCLD with ten repeating units in its chain behaving like a non polymeric material under the conditions applied. The stationary phase with melting temperature ~321 K is in the liquid state in the GC column over the temperature range studied and hence found to be suitable to determine infinite dilution partial molar thermodynamic properties of mixing for solutes on PCLD. The V 0 values have been used to calculate weight fraction activity coefficients Ω∞ and Flory–Huggins interaction parameters, χ 12 ∞ . The average partial molar enthalpy of solution, $$ \overline{\Updelta H}_{1}^{S} , $$ and partial molar enthalpy of mixing, $$ \overline{\Updelta H}_{1}^{\infty } , $$ are calculated using V 0 and Ω∞ respectively. The average molar enthalpy of vaporization ΔH 1 for solutes have been calculated using $$ \overline{\Updelta H}_{1}^{\infty } $$ and $$ \overline{\Updelta H}_{1}^{S} $$ values and compared with the literature values at 363.15 K which is the average column temperature. The partial molar entropy of mixing, $$ \overline{\Updelta S}_{1}^{\infty } $$ calculated at 363.15 K are in good correlation with the average $$ \overline{\Updelta H}_{1}^{\infty } $$ values. The total solubility parameter due to Guillet and the Hansen solubility parameters (HSP) are calculated for PCLD using χ 12 ∞ values. In the present work the Hansen solubility parameters have been calculated using a new method following the Hansen theory and Huang method with less weight on polar and hydrogen bonding components. The errors in the solubility HSP are lower and the correlation coefficients are better in both the methods compared to unweighted three dimensional model.

Phase Equilibrium System of RbCl−SmCl3−HCl(12.84, 22.66 % by Mass)−H2O at 298.15 K and Standard Molar Enthalpy of Formation of RbSmCl4·4H2O

Solubility of the quaternary system RbCl−SmCl3−HCl(12.84, 22.66 % by mass)−H2O was determined at 298.15 K, and corresponding equilibrium diagrams were constructed. The quaternary system is complicated with three equilibrium solid phases RbCl, RbSmCl4·4H2O (1:1 type), and SmCl3·6H2O. The solubilities of RbCl, RbSmCl4·4H2O, and SmCl3·6H2O decreased with an increase of the concentration of HCl. The crystallization field decreased for RbCl and SmCl3·6H2O and increased for RbSmCl4·4H2O with an increase in the HCl concentration. The new solid-phase compound RbSmCl4·4H2O was found to be uncongruently soluble in the system. The compound RbSmCl4·4H2O was characterized by the methods of X-ray diffraction, thermogravimetry, and differential thermogravimetry. The compound loses its crystal water by one step at (359 to 457) K. The standard molar enthalpy of solution of RbSmCl4·4H2O in deionized water was measured to be −(29.40 ± 0.26) kJ·mol−1 by heat conduction microcalorimetry. Its standard molar enthalpy of formation was calculated to be −(2725.3 ± 1.0) kJ·mol−1.

Effect of intramolecular cyclization on the enthalpy of dissolution (solvation) of N,N’-dimethylurea in water and methanol at 298.15 K

The heat effects of dissolution of ethyleneurea (2-imidazolidinone) in water and methanol were measured (with an error not higher than 0.2%) at 298.15 K by using a hermetic isothermal calorimeter. The limiting (standard) molar solution enthalpies of the specified cyclic compound in different solvents were determined. Considerable weakening of the solvation of the solute was established in the case of both cyclization of dimethylurea molecules and replacement of the aqueous medium by a methanolic solution.

Hydrothermal synthesis and thermodynamic properties of 2ZnO · 3B 2O 3 · 3H 2O

The important zinc borate of 2ZnO · 3B 2O 3 · 3H 2O has been synthesized and characterized by means of chemical analysis, XRD, FT-IR, and DTA–TG techniques. The molar enthalpies of solution of H 3BO 3(s) in HCl · 54.561H 2O, of ZnO(s) in the mixture of HCl · 54.561H 2O and calculated amount of H 3BO 3, and of 2ZnO · 3B 2O 3 · 3H 2O(s) in HCl · 54.604H 2O were measured, respectively. With the use of the standard molar enthalpies of formation for ZnO(s), H 3BO 3(s), and H 2O(l), the standard molar enthalpy of formation of −(5561.7 ± 4.9) kJ · mol −1 for 2ZnO · 3B 2O 3 · 3H 2O(s) was obtained. Thermodynamic properties of this compound were also calculated by a group contribution method.

Synthesis and thermochemistry of two zinc borates, Zn 2B 6O 11·7H 2O and Zn 3B 10O 18·14H 2O

Two pure zinc borates, Zn 2B 6O 11·7H 2O and Zn 3B 10O 18·14H 2O have been synthesized and characterized by XRD, FT-IR, DTA–TG techniques and chemical analysis. The molar enthalpies of solution of Zn 2B 6O 11·7H 2O(s) and Zn 3B 10O 18·14H 2O(s) in 1 mol dm −3 HCl(aq) were measured to be 15.42 ± 0.03 kJ mol −1 and 57.78 ± 0.11 kJ mol −1, respectively. The molar enthalpy of solution of ZnO(s) in (HCl + H 3BO 3)(aq) was determined to be −80.01 ± 0.15 kJ mol −1. With incorporation of the previously determined enthalpy of solution of H 3BO 3(s) in 1 mol dm −3 HCl(aq), and the standard molar enthalpies of formation for ZnO(s), H 3BO 3(s), and H 2O(l), the standard molar enthalpies of formation of −6738.1 ± 4.8 kJ mol −1 for Zn 2B 6O 11·7H 2O and −11,786.4 ± 8.0 kJ mol −1 for Zn 3B 10O 18·14H 2O were obtained.