Standard Molar Enthalpies Of Dissolution Research Articles

The standard enthalpy of formation of superionic solid electrolyte Li7La3Zr2O12

The standard enthalpy of formation of perspective solid electrolyte Li7La3Zr2O12 is determined using thermodynamic cycles based on the measurement of its enthalpy of dissolution. The standard molar enthalpies of dissolution in aqueous solution of 1moldm−3 HCl, formation from binary oxides and formation from elements for tetragonal form of Li7La3Zr2O12 are found to be −1547.6, −168.0 and −7152.6kJmol−1, respectively.

Crystal structure and thermochemistry of anhydrous potassium 2-pyrazine carboxylate (C5H3KN2O2)

Potassium 2-pyrazine carboxylate C5H3KN2O2 [abbreviated as K(PCA)(s)] was synthesized, and the synthesis was carried out in the mixed solvent of ethanol and water. Its crystal structure was characterized by X-ray crystallography. And its low-temperature heat capacities were measured by use of a precise automatic adiabatic calorimeter with a small sample in the temperature region of 78–400 K. A polynomial equation of experimental molar heat capacities as a function of the temperature has been obtained. The smoothed molar heat capacities and thermodynamic functions of the compound were calculated based on the fitted polynomial equation. A reasonable thermochemical cycle was designed on the basis of the synthesis reaction of the substance, and the standard molar enthalpies of dissolution for the reactants and products of the reaction in the selected solvent were measured by an isoperibol solution-reaction calorimeter, respectively. The enthalpy change of the reaction was calculated as—(65.396 ± 0.388) kJ mol−1. Finally, the standard molar enthalpy of formation of the title complex was calculated as—(532.106 ± 1.196) kJ mol−1 by using the Hess thermochemical cycle. Furthermore, the reliability of the designed thermochemical cycle was verified by UV–Vis spectra of the solutions obtained from the dissolution of reactants and products.

Crystal structure and thermochemical properties of 2-pyrazine carboxylate lithium monohydrate [Li(pyza)(H2O)] n (s)(pyza=2-pyrazine carboxylate)

A 2-pyrazine carboxylate lithium monohydrate [Li(pyza)(H2O)] n was synthesized in a mixed solution of redistilled water and anhydrous ethanol. X-Ray crystallography was applied to characterizing its crystal structure. Low temperature molar heat capacities were measured in a temperature range of from 78 K to 400 K with a precision automatic adiabatic calorimeter. Two polynomial equations of experimental molar heat capacity as a function of temperature were obtained by the least-squares method. The smoothed molar heat capacities and thermodynamic functions of the compound were calculated based on the fitted polynomial equations. In accordance with Hess’s law, a reasonable thermochemical cycle was designed based on the preparation reaction of the target compound. The standard molar enthalpies of dissolution for the reactants and products of the designed thermochemical reaction were measured by an isoperibol solution-reaction calorimeter, and the enthalpy change of the reaction was obtained, i.e., Δr H m θ =-(30.084±0.329) kJ/mol. The standard molar enthalpy of the formation of the target compound was determined as $\Delta _f H_{m\{ [Li(pyza)(H_2 O)]_n (s)\} }^\theta = - (260.844 \pm 1.178)$ kJ/mol based on the enthalpy change of the reaction and standard molar enthalpies of the formation of other reactants and products. In addition, UV-Vis spectroscopy and the data of the refractive indexes were used to confirm whether the designed Hess thermochemical cycle was reasonable and reliable.

Crystal structure and thermochemistry of a novel coordination compound 2-pyrazine carboxylate sodium

2-Pyrazine carboxylate sodium Na2(PCA)2(s) was synthesized. X-ray crystallography was applied to characterize its crystal structure. Chemical and elemental analyses were used to determine its composition and purity. A precise automatic adiabatic calorimeter was used to measure heat capacities in the temperature range from 78 to 400 K. A polynomial equation of experimental molar heat capacities as a function of the temperature was obtained. The smoothed molar heat capacities and thermodynamic functions of the compound were calculated. The standard molar enthalpies of dissolution for the reactants and products of the synthesis reaction in the selected solvent were measured by an isoperibol solution-reaction calorimeter. The enthalpy change of the reaction was determined to be (1.70 ± 0.82) kJ mol−1, and the standard molar enthalpy of formation of the complex was derived to be −(1,108.70 ± 2.51) kJ mol−1. In addition, the reliability of the designed thermochemical cycle was verified by UV–Vis spectra.

Synthesis, thermochemical and thermokinetic studies on the mononuclear copper Valen Schiff base complex

A mononuclear salen-type complex [Cu( vanen )(H 2 O)] was synthesized from the ligand [H 2 vanen = N , N - ethylene-bis(3-methoxysalicylideneimine)] and Cu(OAc) 2 ·H 2 O. Based on Hess law, a reasonable thermochemical cycle was designed. According to the cycle, the standard molar enthalpies of dissolution of samples in the calorimetric solvent of DMF ( N , N -dimethylformamide) were determined, respectively. The standard molar enthalpy change of the coordination reaction (Δ r H m θ ) was calculated to be -(16.61 ± 0.54) kJ/mol. Combined with some relevant literature data, the standard molar enthalpy of formation (Δ f H m θ ) of the complex was obtained to be -(756.5 ± 2.4) kJ/mol. At the temperature of 32 ℃, the metabolic thermogenetic curves of S. pombe under the influence of the complex with different concentration were determined by using a TAM air isothermal calorimeter. The relationships of the concentration of the complex with the microbial growth rate constant ( k ) of S. pombe , inhibition ratio (I), the half inhibition concentration (IC 50 ), the maximum heat output power ( P max ) and the time it took ( t max ) were analyzed. The results indicated that the complex possessed the Hormesis effect, which promoted the growth of S. pombe at lower concentration, but inhibited the growth at higher concentration.

Synthesis and thermodynamic stability of new phase BaCe0.6Y0.3In0.1O2.8

• We synthesized new phase BaCe 0.6 Y 0.3 In 0.1 O 2.8 . • We measured formation enthalpy of BaCe 0.6 Y 0.3 In 0.1 O 2.8 . • The phase is thermodynamically stable with respect to decomposition into binary oxides at room temperature. • BaCe 0.6 Y 0.3 In 0.1 O 2.8 is more thermodynamically favored than BaCe 0.9 In 0.1 O 2.95 . The preparation of BaCeO 3 doped by yttrium and indium oxides (BaCe 0.6 Y 0.3 In 0.1 O 2.8 ) has been performed by solid-state reaction from BaCO 3 , CeO 2 , Y 2 O 3 , and In 2 O 3 . The compound BaCe 0.6 Y 0.3 In 0.1 O 2.8 has been synthesized for the first time. The X-ray measurements have shown that BaCe 0.6 Y 0.3 In 0.1 O 2.8 has an orthorhombic structure (space group Pmcn ). The standard molar enthalpy of formation of BaCe 0.6 Y 0.3 In 0.1 O 2.8 has been determined by solution calorimetry combining standard molar enthalpies of dissolution of BaCe 0.6 Y 0.3 In 0.1 O 2.8 and BaCl 2 + 0.6CeCl 3 + 0.3YCl 3 + 0.1InCl 3 mixtures in 1 M HCl with 0.1 M KI at 298.15 K and literature data. It has been found out that the mixed oxide mentioned above is thermodynamically stable as to its decomposition into binary oxides at room temperature. It has also been shown that BaCe 0.6 Y 0.3 In 0.1 O 2.8 was more thermodynamically favored than BaCe 0.9 In 0.1 O 2.95 .

Synthesis, crystal structure and thermochemistry of the coordination compound of pyridine-2,6-dicarboxylic acid with barium ion

The complex of pyridine 2,6-dicarboxylate with Ba2+ ion Ba(HDPC)2·2H2O(s) was synthesized. X-ray crystallography was applied to characterize the crystal structure of the complex. Low-temperature heat capacities of the complex were measured with an automated adiabatic calorimeter in the temperature range from 78 to 360K. A polynomial equation of experimental molar heat capacities as a function of the temperature was obtained by the least-squares method. The smoothed heat capacities and thermodynamic functions of the complex were calculated based on the fitted polynomial equation. In addition, the standard molar enthalpies of dissolution for the reactants and products of the synthesis reaction in a selected solvent were measured by an isoperibol solution-reaction calorimeter, and the standard molar enthalpy of formation of the title complex was calculated as – (2993.0±3.0)kJmol−1 by the Hess thermochemical cycle. Furthermore, the reliability of the designed thermochemical cycle was verified by UV–vis spectroscopy.

Synthesis, crystal structure and thermochemistry of nickel hydrogen pyridine-2,6-dicarboxylate

Nickel hydrogen pyridine-2,6-dicarboxylate trihydrate (Ni(HDPC)2·3H2O) was synthesized by the method of liquid phase synthesis. The composition and crystal structure of the complex were determined by chemical analysis, elemental analysis, and X-ray crystallography. Low-temperature heat capacities of the complex were measured over the temperature range from 78 to 353K. Smoothed molar heat capacities and thermodynamic functions of the complex relative to the standard reference temperature 298.15K were calculated based on the fitted polynomial equation. A reasonable thermochemical cycle was designed, and the standard molar enthalpies of dissolution for the reactants and products of the synthesis reaction in a selected solvent were measured. Eventually, the standard molar enthalpy of formation of the title complex was derived to be −(2467.9±3.2)kJmol−1 in accordance with Hess's law.

Synthesis, structural characterization and thermochemistry of copper pyridine 2,6-dicarboxylate trihydrate

Copper pyridine 2,6-dicarboxylate trihydrate (Cu(H2DPC)(DPC)·3H2O) was synthesized. X-ray crystallography, chemical analysis, and elemental analysis were applied to characterize the structure and composition of the complex. Low-temperature heat capacities of the complex were measured with a small sample automated adiabatic calorimeter. The smoothed molar heat capacities and thermodynamic functions of the complex relative to the standard reference temperature 298.15K were calculated based on the fitted polynomial equation. A reasonable thermochemical cycle was designed, and the standard molar enthalpies of dissolution for the reactants and products of the synthesis reaction in a selected solvent were measured by an isoperibol solution-reaction calorimeter. Eventually, the standard molar enthalpy of formation of the title complex was calculated as −(2389.92±2.53)kJmol−1 by the Hess thermochemical cycle. In addition, the reliability of the designed thermochemical cycle was verified by UV–vis spectroscopy.

Synthesis, Structural Characterization, and Thermochemistry of Zinc Hydrogen Pyridine 2,6-Dicarboxylate

Zinc hydrogen pyridine 2,6-dicarboxylate trihydrate (Zn(HDPC)2 · 3H2O) was synthesized. The composition and crystal structure of the complex were determined by chemical analysis, elemental analysis, and X-ray crystallography. Low-temperature heat capacities of the complex were measured with a small sample automated adiabatic calorimeter over the temperature range from 78 K to 379 K. The experimental heat capacities of the complex were fitted by the least-squares method, and a polynomial equation of experimental molar heat capacities versus reduced temperature was obtained. The smoothed molar heat capacities and thermodynamic functions of the complex relative to the standard reference temperature 298.15 K were calculated based on the fitted polynomial equation. A reasonable thermochemical cycle was designed, and the standard molar enthalpies of dissolution for the reactants and products of the synthesis reaction in a selected solvent were measured by an isoperibol solution-reaction calorimeter. The enthalpy change of the synthesis reaction of the titled compound was calculated to be −(15.95 ± 0.43) kJ · mol−1. Eventually, the standard molar enthalpy of formation of the title complex was derived to be −(2582.60 ± 3.02) kJ · mol−1 by the Hess thermochemical cycle. In addition, the reliability of the designed thermochemical cycle was verified by UV–Vis spectroscopy.

Crystal Structures and Thermochemical Properties of n-Nonylammonium Dihydrogen Phosphate C9H19NH3·H2PO4(s) and n-Octylammonium Dihydrogen Phosphate C8H17NH3 ·H 2PO4(s)

The crystal structures of n-nonylammonium dihydrogen phosphate and n-octylammonium dihydrogen phosphate were determined by X-ray crystallography. Lattice potential energies of the compounds were obtained from the crystallographic data. The molar enthalpies of dissolution of the two compounds at various molalities in the double-distilled water were measured at T = 298.15 K by means of an isoperibol solution-reaction calorimeter, respectively. According to the Pitzer's electrolyte solution theory, the standard molar enthalpies of dissolution of the two compounds at infinite dilution were determined to be 34.50 kJ·mol–1 and 22.32 kJ·mol–1, and the Pitzer's parameters βMX(0)L and β MX(1)L were obtained. The values of apparent relative molar enthalpies (ΦL) of the title compounds and relative partial molar enthalpies (L2 and L1 of the solute and the solvent at different concentrations were derived from the experimental values of the enthalpies of dissolution of the two compounds.

Thermochemical properties and thermokinetic behavior of energetic triazole ionic salts

The properties of dissolution in different solvents, the specific heat capacity and thermal decomposition process under the non-isothermal conditions for energetic triazole ionic salts 1,2,4-triazolium nitrate (1a), 1,2,3-triazolium nitrate (1b), 3,4,5-triamino-1,2,4-triazolium nitrate (2a), 3,4,5-triamino-1,2,4-triazolium dinitramide (2b) were precisely measured using a Calvet Microcalorimeter. The thermochemical equation, differential enthalpies of dissolution (ΔdifHmΘ), standard molar enthalpies of dissolution (ΔdifHmΘ), apparent activation energy (E), pre-exponential constant (A), kinetic equation, linear relationship of specific heat capacity with temperature over the temperature range from 283 to 353 K, standard molar heat capacity (Cp,mΘ) and enthalpy, entropy and Gibbs free energy at 283–353 K, taking 298.15 K as the benchmark for 1a, 1b, 2a and 2b were obtained with treating experimental data and theoretical calculation method. The kinetic and thermodynamic parameters of thermal decomposition reaction, critical temperature of thermal explosion (Tb), self-accelerating decomposition temperature (TSADT) and adiabatic time-to-explosion (t) of 1a, 1b, 2a and 2b were calculated. Their heat-resistance abilities were evaluated. Information was obtained on the relation between molecular structures and properties of 1a, 1b, 2a and 2b.

Thermochemistry on K 2[M(DPA) 2]·7H 2O(s) (M = Cu and Ni, H 2DPA = pyridine-2,6-dicarboxylic acid)

Two hybrid transition-alkali metal complexes, K 2[M(DPA) 2]·7H 2O(s) (M = Cu and Ni, H 2DPA = pyridine-2,6-dicarboxylic acid), were structurally determined by X-ray crystallography. In accordance with Hess's law, two reasonable thermochemical cycles were designed and 100 cm 3 of 5% (v/v) dilute aquaammonia was chosen as the calorimetric solvent. The standard molar enthalpies of dissolution for the reactants and products of the supposed reactions in the selected solvent were measured at 298.15 K by means of isoperibol solution-reaction calorimeter, respectively. The standard molar enthalpies of formation of K 2[M(DPA) 2]·7H 2O(s) (M = Cu and Ni) were derived to be −(3947.7 ± 4.7) kJ mol −1 and −(4007.8 ± 4.7) kJ mol −1, respectively.

Low-Temperature Heat Capacities and Standard Molar Enthalpy of Formation of Dichloro Bis(2-aminopyridine) Zinc (II), ZnCl2(C5H6N2)2(s)

Dichloro bis(2-aminopyridine) zinc (II), ZnCl2(C5H6N2)2(s), was synthesized by the method of solvonthermal synthesis in which 2-aminopyridine and zinc chloride were chosen as the reactants. X-ray crystallography, chemical analysis, and elemental analysis were applied to characterize the structure and composition of the complex. Low-temperature heat capacities of the title compound were measured with a precise small-sample automated adiabatic calorimeter over the temperature range from 78 K to 398 K. A polynomial equation of the heat capacities as a function of temperature was fitted by a least-squares method. Smoothed heat capacities and thermodynamic functions of the compound relative to the standard reference temperature (298.15 K) were calculated and tabulated at intervals of 5 K based on the fitted polynomial. A reasonable thermochemical cycle was designed, and the standard molar enthalpies of dissolution for the reactants and products of the synthesis reaction in a selected solvent were measured by an isoperibol solution-reaction calorimeter. In addition, the enthalpy change of the reaction was calculated from the data of the above standard molar enthalpies of dissolution. Finally, the standard molar enthalpy of formation of the complex ZnCl2(C5H6N2)2(s) was determined to be −(400.52 ± 1.66) kJ · mol−1 in accordance with Hess’s law.

Synthesis, crystal structure and standard molar enthalpy of formation of bis( trans-bis( N, N-dimethyl-(1-( R)-phenyl-2-( S)-methyl-2-aminoethoxy-N,O))-copper(II)) heptahydrate

A novel complex, bis( trans-bis( N, N-dimethyl-(1-( R)-phenyl-2-( S)-methyl-2-aminoethoxy-N,O))-copper(II)) heptahydrate (abbreviated as Cu 2(C 11H 16NO) 4·7H 2O(cr)), was synthesized by the method of liquid phase reflux. The composition and structure of the complex were characterized by chemical analysis, elemental analysis, FTIR, and X-ray crystallography. A reasonable thermochemical cycle was designed based on the preparation reaction of the coordination compound, and standard molar enthalpies of dissolution of reactants and products were measured by an isoperibol solution-reaction calorimeter. Finally, the standard molar enthalpy of formation of the complex Cu 2(C 11H 16NO) 4·7H 2O(cr) was determined to be −(4525.22 ± 13.71) kJ · mol −1 in accordance with Hess’s law.

Thermochemical Study on Ternary Complexes of Dysprosium with Aromatic Acids and Phenanthroline

Three ternary Dy(III) complexes were synthesized with aromatic acids (p-nitrobenzoic acid, m-nitrobenzoic acid, and o-chlorobenzoic acid) as the first ligand and 1,10-phenanthroline as the second ligand. In accordance with Hess’s law, a reasonable thermochemical cycle was designed, and standard molar enthalpies of dissolution for the reactants and products of the coordination reactions in the selected solvent were measured by a solution-reaction isoperibol calorimeter, respectively. In addition, the enthalpy changes of the coordination reactions were determined. Finally, the standard molar enthalpies of formation of the three synthetic coordination complexes were estimated to be ΔfHmθ[[Dy(p-NBA)3phen]2·3H2O(s), 298.15 K] = −(5177 ± 8) kJ·mol−1, ΔfHmθ[[Dy(m-NBA)3phen]2·4H2O(s), 298.15 K] = −(5452 ± 6) kJ·mol−1, and ΔfHmθ[[Dy(o-ClBA)3phen]2(s), 298.15 K] = −(5317 ± 7) kJ·mol−1.

Crystal Structure, Lattice Energy, and Standard Molar Enthalpy of Formation of the Complex (C11H18NO)2CuCl4 (s)

AbstractThe complex (C11H18NO)2CuCl4 (s), which may be a potential effective drug, was synthesized. X‐ray crystallography, elemental analysis, and chemical analysis were used to characterize the structure and composition of the complex. Lattice energy and ionic radius of the anion of the complex were derived from the crystal data of the title compound. In addition, a reasonable thermochemical cycle was designed, and standard molar enthalpies of dissolution for reactants and products of the synthesis reaction of the complex were measured by an isoperibol solution‐reaction calorimeter. The enthalpy change of the reaction was calculated to be ΔrH⊖m=(2.69±0.02) kJ·mol−1 from the data of the above standard molar enthalpies of dissolution. Finally, the standard molar enthalpy of formation of the title compound was determined to be ΔrH⊖m[(C11 H18NO)2CuCl4, s]= − (1822.96±6.80) kJ·mol−1 in accordance with Hess law.

Low-Temperature Heat Capacities and Standard Molar Enthalpy of Formation of Ethylenediammonium Tetrachlorocobaltate(II) Chloride (H3NCH2CH2NH3)2[CoCl4]Cl2(s)

A coordination compound, ethylenediammonium tetrachlorocobaltate(II) chloride (H3NCH2CH2NH3)2[CoCl4]Cl2, was synthesized by the method of liquid phase synthesis, in which ethylenediamine, cobalt chloride hexahydrate, and concentrated hydrochloric acid were chosen as the reactants. X-ray crystallography, chemical analysis, and elemental analysis were applied to characterize the structure and composition of the complex. Low-temperature heat capacities of the complex were measured with a precise automated adiabatic calorimeter over the temperature range from (78 to 370) K. A polynomial equation of the heat capacities as a function of temperature was fitted by a least-squares method. Smoothed heat capacities and thermodynamic functions of the compound relative to the standard reference temperature of 298.15 K were calculated and tabulated at intervals of 5 K based on the fitted polynomial equation. A reasonable thermochemical cycle was designed, and the standard molar enthalpies of dissolution of the reactants and products of the synthesis reaction in the selected solvent were measured by an isoperibol solution-reaction calorimeter. The enthalpy change of the reaction was calculated to be ΔrHmo = −(17.612 ± 0.571) kJ·mol−1 from the data of the standard molar enthalpies of dissolution. The standard molar enthalpy of formation of the title compund was determined to be ΔfHmo{(NH3CH2CH2NH3)2[CoCl4]Cl2, s} = −(1499.54 ± 2.73) kJ·mol−1 in accordance with Hess’s law.

Low-Temperature Heat Capacities and Thermodynamic Properties of Triaquabenzoatocalcium Monobenzoate [Ca(Ben)(H2O)3](Ben)(s) (Ben = Benzoate)

Triaquabenzoatocalcium monobenzoate [Ca(Ben)(H2O)3](Ben)(s) was synthesized by the method of liquid phase reaction. Chemical and element analyses and X-ray crystallography were used to characterize the composition and structure of the complex. The lattice potential energy of the compound was calculated to be UPOT = 426.61 kJ·mol−1 on the basis of crystal structure information. Low-temperature heat capacities over the temperature range from (78 to 360) K were measured by an automated adiabatic calorimeter, and a polynomial equation was fitted by the least-squares method. On the basis of the fitted polynomial, the smoothed heat capacities and thermodynamic functions of the compound relative to the standard reference temperature 298.15 K were calculated at intervals of 5 K. The thermal decomposition of the complex was studied using TG and DSC analyses. In accordance with Hess’s law, a reasonable thermochemical cycle was designed based on the preparation reaction of the compound. The standard molar enthalpies of dissolution for the reactants and product of the reaction in the selected solvent were measured by an isoperibol solution-reaction calorimeter. The enthalpy change of the liquid phase reaction was calculated to be ΔrHmo = −(46.68 ± 0.40) kJ·mol−1, and the standard molar enthalpy of formation of the complex was determined to be ΔfHmo[Ca(Ben)(H2O)3](Ben),s = −(2088.2 ± 1.1) kJ·mol−1 by means of the enthalpy change of the reaction and other auxiliary thermodynamic quantities.

Low-Temperature Heat Capacities and Standard Molar Enthalpy of Formation of Potassium Benzoate C7H5O2K(s)

Potassium benzoate C7H5O2K (CAS Registry No. 582-25-2) was synthesized by the method of liquid phase reaction. Chemical and elemental analyses, FTIR, and X-ray powder diffraction (XRD) techniques were applied to characterize the composition and structure of the compound. Low-temperature heat capacities of the compound were measured by a precision automated adiabatic calorimeter over the temperature range from 78 K to 398 K. A polynomial equation of the heat capacities as a function of temperature was fitted by the least-squares method. Smoothed heat capacities and thermodynamic functions of the compound were calculated based on the fitted polynomial. In accordance with Hess’s law, a reasonable thermochemical cycle was designed, and 100 mL of 1 mol · dm−3 NaOH solution was chosen as the calorimetric solvent. The standard molar enthalpies of dissolution for the reactants and products of the supposed reaction in the selected solvent were measured by an isoperibol solution-reaction calorimeter. Finally, the standard molar enthalpy of formation of the title compound C7H5O2K (s) was derived to be -(610.94 ± 0.77) kJ · mol−1.