Isoperibol Solution-reaction Calorimeter Research Articles

The Estimation of Standard Molar Enthalpies of Solution for VOSO4⋅nH2O(s) in Water and in Aqueous H2SO4

The molar enthalpies of solution of VOSO4⋅3.52H2O(s) at various molalities in water and in aqueous sulfuric acid (0.1 mol⋅kg−1), ΔsolHm, were measured by a solution-reaction isoperibol calorimeter at 298.15±0.01 K. An improved Archer’s method to estimate the standard molar enthalpy of solution, \(\Delta_{\mathrm{sol}}H^{0}_{\mathrm{m}}\), was put forward. In terms of the improved method, the values of \(\Delta_{\mathrm{sol}}H^{0}_{\mathrm{m}}=-24.12\pm 0.03~\mbox{kJ}{\cdot}\mbox{mol}^{-1}\) of VOSO4⋅3.52H2O(s) in water and \(\Delta_{\mathrm{sol}}H^{0}_{\mathrm{m}}=-15.38\pm 0.06~\mbox{kJ}{\cdot}\mbox{mol}^{-1}\) in aqueous sulfuric acid were obtained, respectively. The data indicates that the energy state of VOSO4 in aqueous H2SO4 is higher than that in pure water.

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 ethylenediammonium tetrachlorozincate chloride (C 2H 10N 2) 2(ZnCl 4)Cl 2

The ethylenediammonium tetrachlorozincate chloride (C 2H 10N 2) 2(ZnCl 4)Cl 2 was synthesized. Chemical analysis, elemental analysis, and X-ray crystallography were applied to characterize the composition and crystal structure of the complex. Low-temperature heat capacities of the compound were measured by a precision automatic adiabatic calorimeter over the temperature range from T = 77–377 K. A polynomial equation of heat capacities as a function of the reduced temperature was fitted by a least square method. Based on the polynomial equation, the smoothed heat capacities and thermodynamic functions of the title compound relative to the standard reference temperature 298.15 K were calculated at intervals of 5 K. A thermochemical cycle was designed and the enthalpy change of the solid phase reaction of ethylenediamine dihydrochloride with zinc chloride was determined to be Δ r H m ° = − ( 17.9 ± 0.6 ) kJ mo l − 1 by an isoperibol solution-reaction calorimeter. Finally, the standard molar enthalpy of formation of the title compound was derived to be Δ f H m ° [ ( C 2 H 10 N 2 ) 2 ( ZnC l 4 ) C l 2 , s ] = − ( 1514.4 ± 2.7 ) kJ mo l − 1 in accordance with Hess law.

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]−.

Thermochemistry of the solid-state coordination compounds (C 2H 10N 2)MCl 4(s) (M = Cd and Cu)

Tetrachlorocuprate (II) ethylenediammonium (C 2H 10N 2)CuCl 4(s) and tetrachlorocadmate (II) ethylenediammonium (C 2H 10N 2)CdCl 4(s) were synthesized. Chemical analysis, elemental analysis, and X-ray crystallography were applied to characterize the compositions and crystal structures of the two complexes. In accordance with Hess law, two thermochemical cycles were designed, and the enthalpy changes of the reactions of ethylenediamine dihydrochloride with CuCl 2·2H 2O(s) and CdCl 2·2.5H 2O(s) were determined as Δ r H m, 1 ∘ = ( 5.89 ± 0.22 ) kJ · mol - 1 and Δ r H m, 2 ∘ = - ( 2.88 ± 0.26 ) kJ · mol - 1 by use of an isoperibol solution–reaction calorimeter, respectively. The standard molar enthalpies of formation of the title complexes (C 2H 10N 2)CuCl 4(s) and (C 2H 10N 2)CdCl 4(s) were derived to be Δ f H m ∘ [(C 2H 10N 2)CuCl 4, s] = −(784.51 ± 1.35) kJ · mol −1 and Δ f H m ∘ [(C 2H 10N 2)CdCl 4, s] = −(960.99 ± 1.36) kJ · mol −1, respectively.

Synthesis, characterization, and thermodynamic study of ammonium benzoate C 7H 5O 2NH 4(s)

Benzoic acid and concentrated ammonia were chosen as reactants and a novel compound (ammonium benzoate) was synthesized using the method of liquid phase reaction. FTIR, elemental analysis and X-ray powder diffraction technique were applied to characterize the structure and composition of the compound. Low-temperature heat capacities of the solid compound were measured by a precision automated adiabatic calorimeter over the temperature range from 80 to 399 K. A polynomial equation of the heat capacities was fitted by the least-squares method. In accordance with Hess’ law, a thermochemical cycle was designed, the enthalpy change of the reaction of benzoic acid with ammonium acetate was determined as Δ r H m ° = ( 15.59 ± 0.50 ) kJ mo l − 1 , and the standard molar enthalpy of formation of the compound was calculated as Δ f H m ° [ C 7 H 5 O 2 N H 4 ,s ] = − ( 472.65 ± 0.62 ) kJ mo l − 1 by an isoperibol solution–reaction calorimeter.

Low-Temperature Heat Capacities and Standard Molar Enthalpy of Formation of Potassium Hydrogen Phthalate C8H5KO4(s)

Potassium hydrogen phthalate (KHP) was synthesized by the method of liquid-phase synthesis, in which phthalic acid and potassium hydroxide were chosen as the reactants. The structure and composition of the compound were characterized by chemical and elemental analyses, X-ray powder diffraction, and X-ray crystallography. Low-temperature heat capacities of the compound were measured by a precision automated adiabatic calorimeter over the temperature range from (78 to 400) K. A polynomial equation of the heat capacities as a function of the temperature was fitted by a least-squares method. The smoothed heat capacities and the thermodynamic functions of the compound relative to 298.15 K were calculated and tabulated at an interval of 5 K. In accordance with Hess’ law, a thermochemical cycle was designed. The enthalpy change of the reaction of phthalic acid with potassium acetate was determined to be ΔrHmo = −(4.298 ± 0.493) kJ·mol−1 by use of an isoperibol solution-reaction calorimeter, and the standard mola...

Lattice potential energy and thermochemical properties of ethylenediamine dihydrochloride (C 2H 10N 2Cl 2)

Ethylenediamine dihydrochloride (C 2H 10N 2Cl 2)(s) was synthesized. The crystal structure of the compound has been determined by X-ray crystallography. The lattice potential energy and ionic radius of the cation of the compound were obtained from the crystallographic data. Molar enthalpies of dissolution of the compound in double-distilled water under various values of molality were determined at T = 298.15 K by an isoperibol solution-reaction calorimeter. Following to Pitzer’s theory, the molar enthalpy of dissolution of the compound at infinite dilution ( Δ sol H m ∞ ) and the Pitzer parameters ( β MX ( 0 ) L and β MX ( 1 ) L ) were obtained. The values of relative apparent molar enthalpies ( Φ L ), relative partial molar enthalpies ( L ¯ 2 ) of the compound and relative partial molar enthalpies ( L ¯ 1 ) of the solvent at different concentrations m/(mol · kg −1) were derived from the experimental values of the enthalpies of dissolution of the compound. Finally, the hydration enthalpy of the cation of the substance was calculated by designing a thermochemical cycle.

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.

Crystal structure and thermochemical properties of 1-dodecylamine hydrochloride (C 12H 28NCl)(s)

Crystal structure of 1-dodecylamine hydrochloride (C 12H 28NCl)(s) has been determined by an X-ray crystallography. Lattice potential energy and the molar volumes of the solid compound and its cation were respectively obtained. The enthalpy of dissolution of the compound was measured by an isoperibol solution-reaction calorimeter at 298.15 K. The molar enthalpy of dissolution at infinite dilution was determined to be Δ s H m θ = 30.36 kJ mo l − 1 , and relative apparent molar enthalpies ( Φ L ), relative partial molar enthalpies ( L 2) of the compound and relative partial molar enthalpies ( L 1) of the solvent (double distilled water) at different concentrations m (mol kg −1) were obtained through fitted multiple regression equation by means of Pitzer's theory. Finally, hydration enthalpies of the substance and its cation were calculated by designing a thermochemical cycle in accordance with lattice potential energy and the molar enthalpy of dissolution at infinite dilution ( Δ s H m θ ) .

Thermochemistry on the Solid State Coordination Compounds M(Nic)2 · H2O(s) (M = Mn and Mg, Nic = Nicotinate)

Abstract Two novel solid state coordination compounds – manganese nicotinate monohydrate and magnesium nicotinate monohydrate were synthesized by the method of room temperature solid phase synthesis and ball grinder. FTIR, chemical and elemental analyses and X-ray powder diffraction techniques were applied to characterize the structure and composition of these complexes. In accordance with Hess’ law, hermochemical cycles were designed, the enthalpy changes of the solid phase reactions of nicotinic acid with manganese acetate tetrahydrate and magnesium acetate tetrahydrate were determined as Δr H 0 m,l = (39.66±0.36) kJ · mol–1 and Δr H 0 m,2 = (40.73±0.17) kJ · mol–1 by use of an isoperibol solution-reaction calorimeter, respectively. The standard molar enthalpy of formation of the title complexes M(Nic)2 · H2O(s) were calculated as Δf H 0 Mn(Nic)2·H2O = –(1165.01±2.01) kJ · mol–1 and Δf H 0 Mg(Nic)2·H2O = –(1390.49±1.99) kJ · mol–1 by use of the enthalpies of dissolution and other auxiliary thermodynamic data. In addition, the values of the standard molar enthalpies of formation of M(Nic)2·H2O(s) (M = Mg, Mn, Zn) were compared, a law of change of [–Δf H 0 Zn(Nic)2·H2O] < [–Δf H 0 Mn(Nic)2·H2O] < [–Δf H 0 Mg(Nic)2·H2O] can be obtained, and was in relation with the stability of the three monohydrated nicotinates.

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.

Thermochemistry on ephedrine hydrochloride and N-methylephedrine hydrochloride

The crystal structures of ephedrine hydrochloride and N-methylephedrine hydrochloride have been determined by X-ray crystallography. The molar enthalpies of dissolution of the two compounds with various molalities were measured at T = 298.15 K in distilled water by means of isoperibol solution-reaction calorimeter, respectively. According to the theory of Pitzer, the molar enthalpies of dissolution of the two compounds at infinite dilution, Δ s H m ∞ , and Pitzer’s parameters β MX ( 0 ) L , β MX ( 1 ) L , and C MX Φ L , were obtained. Then the values of apparent relative molar enthalpies ( Φ L ) , hydration heat, and relative partial molar enthalpies of the two compounds ( L ¯ 2 ) were derived from the experimental results of the enthalpies of dissolution of the two compounds. Finally, the ionic radius of the cations can be calculated from the data of the corresponding effective volume of the cations.

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.

Low temperature heat capacities and standard molar enthalpy of formation of sodium benzoate C 6H 5COONa (s)

Sodium benzoate was synthesized by the method of liquid phase synthesis, in which benzoic acid and anhydrous sodium carbonate were chosen as the reactants. The structure and composition of the compound were characterized by FTIR, chemical analysis, elemental analysis and X-ray powder diffraction techniques. Low temperature heat capacities of the compound were measured by a precision automated adiabatic calorimeter over the temperature range from 78 to 400 K. A polynomial equation of the heat capacities as a function of the temperature was fitted by least square method. The smoothed heat capacities and the thermodynamic functions of the compound relative to 298.15 K have been calculated based on the equation. In accordance with Hess law, the standard molar enthalpy of formation of the title compound C 6H 5COONa (s) was determined to be Δ f H ° m [ C 6 H 5 COONa , s ] = − ( 642.56 ± 0.64 ) kJ mo l − 1 by using an isoperibol solution-reaction calorimeter.

Studies on thermochemical properties of ionic liquids based on transition metal

Abstract A brown and transparent ionic liquid (IL), [C4mim][FeCl4], was prepared by mixing anhydrous FeCl3 with 1-butyl-3-methylimidazolium chloride ([C4mim][Cl]), with molar ratio 1/1 under stirring in a glove box filled with dry argon. The molar enthalpies of solution, Δs H m, of [C4mim][FeCl4], in water with various molalities were determined by a solution-reaction isoperibol calorimeter at 298.15 K. Considering the hydrolyzation of anion [FeCl4]− in dissolution process of the IL, a new method of determining the standard molar enthalpy of solution, Δs H m0, was put forward on the bases of Pitzer solution theory of mixed electrolytes. The values of Δs H m0 and the sum of Pitzer parameters: \documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{upgreek} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \b...

Synthesis, characterization, and thermochemistry of the solid state coordination compound Zn(Nic) 2 · H 2O(s) (Nic = nicotinic acid)

A novel compound, viz. zinc nicotinate monohydrate, was synthesized by the method of room temperature solid phase synthesis. The techniques of FT-IR chemical and elemental analyses and X-ray powder diffraction were applied to characterise the structure and composition of the complex. In accordance with Hess’ law, a thermochemical cycle was designed and the enthalpy change of the solid phase reaction of nicotinic acid with hydrated zinc acetate was determined to be Δ r H m ∘ = ( 46.71 ± 0.21 ) kJ · mol - 1 by use of an isoperibol solution-reaction calorimeter. The standard molar enthalpy of formation of the title complex Zn(Nic) 2 · H 2O(s) was calculated as −(1062.3 ± 2.0) kJ · mol −1 by use of the enthalpies of dissolution and other auxiliary thermodynamic data.

Synthesis, Characterization, and Thermodynamic Study of the Coordination Compound Cd(HNic)2Cl2(s)

Nicotinic acid and cadmium chloride were used as the reactants, absolute ethanol as solvent, and a novel coordination compound Cd(HNic)2Cl2 was synthesized by the method of liquid phase reaction. Chemical and elemental analyses, FTIR, and X-ray powder diffraction techniques were applied to characterize its composition and structure. Low-temperature heat capacities of the solid coordination compound have been measured by a precision automated adiabatic calorimeter over the temperature range from T = 78 K to T = 400 K. The experimental values of the molar heat capacities in the temperature region were fitted to a polynomial. Smoothed heat capacities and thermodynamic functions of the complex relative to 298.15 K were calculated based on the fitted polynomial and tabulated at 5 K intervals. In accordance with Hess’s law, a reasonable thermochemical cycle was designed based on the preparation reaction of the new substance, and 100 mL of 0.1 M HCl solution was chosen as the calorimetric solvent. 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. The enthalpy change of the liquid phase reaction was determined as ΔrHmo = (23.46 ± 0.30) kJ·mol−1, and the standard molar enthalpy of formation of the complex was determined to be −(1088.8 ± 1.9) kJ·mol−1 by means of the enthalpy change of the reaction and other auxiliary thermodynamic quantities.

Standard Molar Enthalpies of Formation for Ammonium/3d-Transition Metal Phosphates NH4MPO4·H2O (M = Mn2+, Co2+, Ni2+, Cu2+)

Ammonium/transition metal phosphate monohydrate NH4MPO4·H2O (M = Mn2+, Co2+, Ni2+, Cu2+) compounds were synthesized by solid-state reaction at low temperature and characterized by X-ray diffraction (XRD), FT-IR, and chemical analysis. Based on Hess’s law, the thermochemical cycles were designed for measuring the dissolution enthalpies of reactants and products using a solution-reaction isoperibol calorimeter at 298.15 K. From the dissolution enthalpies, the molar enthalpies of the five reactions designed were calculated individually. With these data and other auxiliary theromodynamic data, the standard molar enthalpies of formation of the title compounds were concluded as: ΔfHmΘ[NH4MnPO4·H2O] = (−1925.01 ± 0.25) kJ·mol−1, ΔfHmΘ[NH4CoPO4·H2O] = (−1754.91 ± 0.43) kJ·mol−1, ΔfHmΘ[NH4NiPO4·H2O] = (−1755.48 ± 0.39) kJ·mol−1, and ΔfHmΘ[NH4CuPO4·H2O] = (−1636.41 ± 0.36) kJ·mol−1.

A versatile and high-precision solution—reaction isoperibol calorimeter

A new solution-reaction isoperibol calorimeter was developed to measure enthalpies of solution and reaction. A new system of sample cell was developed to avoid the breaking of glass ampoules, hence making the sample cell reusable. The system is suitable for measuring molar enthalpies of solid-liquid and liquid-liquid interactions at different temperatures. The reproducibility and accuracy of the apparatus were tested by measuring the enthalpy of solution of KCl in water at 298.15 K and the enthalpy of protonation of THAM in HCl (0.1 M) at 298.15 K. The results showed the uncertainty taken as the reproducibility was ±0.3% and the difference with the literature values was within ±0.5%.