Automatic Adiabatic Calorimeter Research Articles

Comprehensive comparisons of crystal structure, Hirshfeld surface and thermochemical properties of two succinic acid metal complexes [LiC2H2O2]2(s) and [NaC2H2O2·3H2O]2(s)

In this work, two aqueous and nonaqueous metal complexes of succinic acid were synthesized, namely Li-succinate (CCDC: 2284044) and hexahydrate Na-succinate (CCDC: 2296979). Their crystal structures were determined by single crystal X-ray crystallography. The Li-succinate crystallizes in trigonal space group R3¯ and the hexahydrate Na-succinate in triclinic P1¯. The Hirshfeld surfaces and the corresponding 2D fingerprints of the two complexes were recorded, showing that the nature of the intermolecular interactions between Li-succinate are mainly coordination bonds and that the intermolecular interactions between hexahydrate Na-succinate are mainly intermolecular hydrogen formation. The experimental heat capacities of the two complexes in the low-temperature interval were determined using a precise automatic adiabatic calorimeter, and the polynomial equations for the variation of the heat capacities with the folding transition temperature were obtained by fitting the measured experimental heat capacities using the least squares method, on the basis of which the values of their Sulpine heat capacities at intervals of 5 K in the low temperature interval and the values of their thermodynamic functions with respect to 298.15 K were calculated. The TG/DSC curves also reveal the molecular structure of the title complexes.

Low-temperature heat capacity and standard thermodynamic functions of 1-butyl-3-methylimidazolium lactate

The heat capacities of 1-butyl-3-methylimidazolium lactate ionic liquids ([C4mim][Lact]) were measured with a highly accurate automatic adiabatic calorimeter over the temperature range from 79 to 406 K. And the experimental values of molar heat capacities were fitted to a polynomial equation using least square method in the appropriate temperature ranges. The standard molar heat capacity was determined to be 1734.46 ± 5.12 J K−1 mol−1 at 298.15 K. The molar enthalpy and molar entropy of the transition were determined to be 15.575 ± 0.045 and 64.44 ± 0.14 J K−1 mol−1. Other thermodynamic properties, such as (HT − H298.15) and (ST − S298.15), were also calculated. Furthermore, when the temperature reaches 241.87 K, the strongest peaks appeared by analysis of the heat capacity curve. This phenomenon could be explained from the interionic interaction, which is the hydrogen bond between the anions and cations.

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.

Crystal structures and solid–solid phase transitions on phase change materials (1−CnH2n+1NH3)2CuCl4(s) (n=10 and 11)

Two novel crystalline complexes (C10H21NH3)2CuCl4(s) and (C11H23NH3)2CuCl4(s) (abbreviated as C10Cu(s) and C11Cu(s)), which may be used as the phase change materials, were synthesized by liquid phase reaction. Crystal structures and chemical compositions of the two complexes were determined by X-ray single crystal diffraction technique, chemical analysis and elemental analysis. Low-temperature heat capacities of the two new phase change materials were measured by a precise automatic adiabatic calorimeter in the temperature range from 78 to 395K. The temperatures, molar enthalpies and entropies of the phase transitions for each of the two complexes were determined to be: for (C10Cu(s)), 310.64±0.05K, 81.12±0.11kJ/mol, and (261.24±0.06) J/Kmol for the first peak, 315.17±0.04K, 10.17±0.52kJ/mol, and 32.28±1.66J/Kmol for the second peak; for (C11Cu(s)), they were 311.39±0.69K, 70.17±0.25kJ/mol, and 225.36±0.66J/Kmol for the first peak, 321.85±0.46K, 10.58±0.26kJ/mol, and 32.86± 0.07J/Kmol for the second peak, respectively. Two polynomial equations of the heat capacities as a function of temperature were fitted by the least-square method. Smoothed heat capacities and thermodynamic functions of the two phase change materials were calculated based on the fitted polynomial equations. In addition, the solid–solid phase transitions and melting processes of the two complexes were verified by DSC and TG techniques, and the reversibility and repeatability of the two phase transitions for each of the two complexes were discussed.

Crystal structure and thermodynamic properties of phase change material bis(1-dodecylammonium) tetrachlorochromate (C12H25NH3)2CdCl4(s)

A novel complex bis(1-dodecylammonium) tetrachlorochromate (C12H25NH3)2CdCl4(s) (abbreviated as C12Cd(s)) was synthesized by liquid phase reaction. Crystal structure and composition of the complex were determined by X-ray crystallography, chemical analysis, and elemental analysis. It is triclinic, the space group is P−1 and Z = 2. Lattice potential energy (LPE) of the complex was calculated to be kJ·mol−1 from crystallographic data. Low-temperature heat capacities were measured by a precise automatic adiabatic calorimeter over the temperature range from 78 to 370 K. The temperature, molar enthalpy, and entropy of the phase transition of the complex were determined to be 331.88 ± 0.02 K, 55.79 ± 0.46 kJ·mol−1, and 168.10 ± 1.38 J·K−1·mol−1, respectively. Two polynomial equations of the heat capacities as a function of temperature were fitted by least-square method. Smoothed heat capacities and thermodynamic functions of the complex were calculated.

Molar heat capacity and thermodynamic properties of crystalline Eu(C2H5O2N)2Cl3·3H2O

A complex of europium hydrochloric acid coordinated with 2-aminoacetic acid (C2H5O2N), Eu(C2H5O2N)2Cl3·3H2O was synthesized and characterized by IR and elements analysis. The heat capacities of the complex was measured with an automatic adiabatic calorimeter, and the thermodynamic functions [H T − H 298.15] and [S T − S 298.15] were derived in the temperature range from 80 to 340 K with temperature interval of 5 K. Thermal decomposition behavior of the complex in nitrogen atmosphere was studied by thermogravimetric (TG) analysis and differential scan calorimeter (DSC).

Crystal structures and thermodynamic properties of phase change materials (1-CnH2n+1NH3)2CdCl4(s) (n = 15 and 16)

Abstract Two novel crystalline compounds (1-C15H31NH3)2CdCl4(s) and (1-C16H33NH3)2CdCl4(s), which may be used as the solid–solid phase change materials, were synthesized. X-ray crystallography was applied to characterize crystal structures of the two compounds. Both of them are monoclinic, the space group is both C2/c, and Z = 4. Lattice potential energies (UPOT) of the title compounds were calculated to be 832.31 kJ mol−1 for (1-C15H31NH3)2CdCl4(s) and 814.26 kJ mol−1 for (1-C16H33NH3)2CdCl4(s). Low-temperature heat capacities of the two compounds were measured by a precise automatic adiabatic calorimeter in the temperature range from 78 to 395 K. The temperatures, molar enthalpies and entropies of two phase transitions for each of the two compounds were determined. The smoothed heat capacities and thermodynamic functions of the two compounds relative to the standard reference temperature 298.15 K were calculated and tabulated at 5 K intervals based on experimental heat capacities.

Crystal structure and thermochemical properties of bis(1-octylammonium) tetrachlorochromate phase change materials

A new crystalline complex (C8H17NH3)2CdCl4(s) (abbreviated as C8Cd(s)) is synthesized by liquid phase reaction. The crystal structure and composition of the complex are determined by single crystal X-ray diffraction, chemical analysis, and elementary analysis. It is triclinic, the space group is P−1 and Z = 2. The lattice potential energy of the title complex is calculated to be UPOT (C8Cd(s))=978.83 kJ·mol−1 from crystallographic data. Low-temperature heat capacities of the complex are measured by using a precision automatic adiabatic calorimeter over a temperature range from 78 K to 384 K. The temperature, molar enthalpy, and entropy of the phase transition for the complex are determined to be 307.3±0.15 K, 10.15±0.23 kJ·mol−1, and 33.05±0.78 J·K−1·mol−1 respectively for the endothermic peak. Two polynomial equations of the heat capacities each as a function of temperature are fitted by using the least-square method. Smoothed heat capacity and thermodynamic functions of the complex are calculated based on the fitted polynomials.

Low-temperature heat capacities, and thermodynamic properties of solid–solid phase change material bis(1-octylammonium) tetrachlorocuprate

A new crystalline complex (C8H17NH3)(2)CuCl4(s) (abbreviated as C8Cu(s)) was synthesized by liquid phase reaction. 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 complex were measured by a precision automatic adiabatic calorimeter over the temperatures ranging from 78 to 395 K, and two solid-solid phase changes appeared in the heat capacity curve. The temperatures, molar enthalpies and entropies of the two phase transitions of the complex were determined to be: T (trs, 1) = 309.4 +/- A 0.35 K, Delta(trs) H (m, 1) = 16.55 +/- A 0.41 kJ mol(-1), and Delta(trs) S (m, 1) = 53.49 +/- A 1.3 J K-1 mol(-1) for the first peak; T (trs, 2) = 338.5 +/- A 0.63 K, Delta(trs) H (m, 2) = 6.500 +/- A 0.10 kJ mol(-1), and Delta(trs) S (m, 2) = 19.20 +/- A 0.28 J K-1 mol(-1) for the second peak. Two polynomial equations of the heat capacities as a function of the temperature were fitted by least-square method. Smoothed heat capacities and thermodynamic functions of the complex relative to the standard reference temperature of 298.15 K were calculated based on the fitted polynomial equations.

Synthesis, Crystal Structure and Low-temperature Heat Capacities of Bis(n-undecylammonium)tetrachlorocadmiumate

The crystalline bis(n-undecylammonium)tetrachlorocadmiumate (C11H23NH3)2CdCl4(s) (abbre- viated as C11Cd(s)) was synthesized. The crystal structure and composition of the complex were determined by single crystal X-ray diffraction, chemical analysis and elementary analysis. The lattice potential energy was calculated to be UPOT=908.18 kJmol -1 from crystallographic data. Low-temperature heat capacities of the complex were measured by a precision automatic adiabatic calorimeter over the temperature range from 78 to 395 K. The experimental results show that there are two continuous phase changes appearing in the temperature region. The peak temperatures, molar enthalpies and entropies of two phase transitions for the complex were determined to be: Ttrs,1=(321.88±0.07) K, ΔtrsHm,1=(37.59±0.17) kJmol -1 and ΔtrsSm,1=

Crystal structures and thermochemistry on phase change materials ( n-C nH 2 n+1 NH 3) 2CuCl 4(s) ( n=14 and 15)

Crystalline compounds (C 14H 29NH 3) 2CuCl 4(s) and (C 15H 31NH 3) 2CuCl 4(s) were synthesized. X-ray crystallography was applied to characterize crystal structures of the two compounds. The crystal system is both monoclinic, the space group is both C2/ c, and Z=4. The lattice potential energies of the title compounds were calculated to be U POT [(C 14H 29NH 3) 2CuCl 4, s]=853.12 kJ/mol and U POT [(C 15H 31NH 3) 2CuCl 4, s]=854.93 kJ/mol. Low-temperature heat capacities of the two compounds were measured by a precision automatic adiabatic calorimeter over the temperature range from 78 to 395 K. The temperatures, molar enthalpies, and entropies of two phase transitions for each of the two complexes were determined to be: for (C 14H 29NH 3) 2CuCl 4(s), 342.35±0.11 K, 76.17±0.40 kJ/mol, and 222.49±1.20 J/K mol for the first peak; 352.61±0.09 K, 27.83±0.27 kJ/mol, and 78.92±0.78 J/K mol for the second peak, and for (C 15H 31NH 3) 2CuCl 4(s), they were 345.40±0.93 K, 62.06±1.07 kJ/mol, and 179.67±2.63 J/K mol for the first peak; 360.98±0.25 K, 21.66±0.76 kJ/mol, and 60.00±2.09 J/K mol for the second peak, respectively. The smoothed heat capacities and thermodynamic functions ( H T ο − H 298.15 ο ) and ( Δ trs S m = Δ trs H m / T trs ) of the two compounds were calculated with an interval of 5 K based on the experimental heat capacities.

Low‐temperature Heat Capacities and Thermodynamic Properties of the Solid State Complexes (C2H10N2)MCl4 (s) (M=Cu and Cd)

AbstractThe tetrachlorocuprate(II) ethylenediammonium and tetrachlorocadmate(II) ethylenediammonium were synthesized. Chemical analysis, elemental analysis, and X‐ray crystallography were applied to characterize the compositions and crystal structures of the two complexes. The lattice potential energies and the radiuses of the anions of two complexes were calculated to be UPOT[(C2H10N2)CuCl4]=1810.19 kJ·mol−1, UPOT[(C2H10N2)CdCl4]=1784.39 kJ·mol−1, r[(CuCl4)2−]=0.308 nm, and r[(CdCl4)2−]=0.321 nm from the data of the crystal structure, respectively. Low‐temperature heat capacities of the two complexes were measured by a precision automatic adiabatic calorimeter with the small sample over the temperature range from 78 to 400 K, respectively. Two polynomial equations of heat capacities against the temperatures were fitted by least square method: Cp,m[(C2H10N2)CuCl4, s] =213.553+118.578X−5.816X2+4.392X3+0.276X4 and Cp,m[(C2H10N2)CdCl4, s] =190.927+98.501X−7.931X2+0.657X3+3.834X4, in which X= (T−239)/161. Based on the fitted polynomial equations, the smoothed heat capacities and thermodynamic functions of the two complexes relative to the standard reference temperature 298.15 K were calculated at intervals of 5 K.

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.

Investigation on Thermodynamic Properties of a Water-Based Hematite Nanofluid

A friendly environmental method was used to prepare a water-based hematite (α-Fe2O3) nanofluid through a simple biomolecule-assisted hydrothermal process. The molar heat capacities of the obtained nanofluids, base fluids, and hematite nanoparticles were measured by a high-precision automatic adiabatic calorimeter over the temperature range of (290 to 335) K, respectively. Polynomial equations of the molar heat capacities as a function of temperature were fitted by a least-squares method for the solid and nanofluid samples. Smoothed heat capacities and thermodynamic functions of the obtained samples, such as H(T/K) − H(298.15 K) and S(T/K) − S(298.15 K), were calculated on the basis of the fitted polynomials and the relationships of the thermodynamic functions. On the basis of the as-obtained molar heat capacities, the excess heat capacities of the nanofluids were calculated. These excess heat capacities reveal that the stable hematite nanofluids exhibit unique properties compared with the unstable one.

Low-temperature heat capacities of crystalline Ho(Gly) 3Cl 3 · 3H 2O from 78 to 348 K

Heat capacities of the rare-earth complex with glycine [Ho(Gly) 3Cl 3 · 3H 2O] were measured with a high-precision automatic adiabatic calorimeter over the temperature range from 78 to 348 K. In the experimental temperature range, the heat capacities increased in a smooth and continuous manner and no phase transition or thermal anomaly occurred. Therefore, the sample was stable in the above temperature range. The values of experimental heat capacities were fitted to a polynomial equation with least square method and the thermodynamic functions, ( H T—H 298.15) and ( S T—S 298.15), were calculated.

Thermodynamic Study on Complex of Terbium with Glycine Tb(Gly)2Cl3·3H2O

AbstractA terbium complex with glycine Tb(Gly)2Cl3·3H2O was synthesized and its IR spectrum was determined. The heat capacity of the complex was measured with a high‐precision automatic adiabatic calorimeter over the temperature range from 81 to 378 K. From 170 to 247 K, two solid‐solid phase transitions occurred at 186.054 and 244.063 K, respectively. Thermal decomposition of the complex was studied by thermogravimetric (TG) techniques and a possible mechanism for the decomposition was suggested. By isoperibol solution‐reaction calorimetry, the standard molar enthalpy of formation of Tb(Gly)2Cl3·3H2O was derived to be − (3109.5±3.1) kJ·mol−1.

Molar heat capacity and thermodynamic properties of crystalline [Nd(Glu)(H2O)5(Im)3](ClO4)6·2H2O

A complex of neodymium perchloric acid coordinated with L-glutamic acid and imidazole, [Nd(Glu)(H2O)5(Im)3](ClO4)6·2H2O was synthesized and characterized by IR and elements analysis for the first time. The thermodynamic properties of the complex were studied with an automatic adiabatic calorimeter and differential scanning calorimetry (DSC). Glass transition and phase transition were discovered at 221.83 and 245.45 K, respectively. The glass transition was interpreted as a freezing-in phenomenon of the reorientational motion of ClO4− ions and the phase transition was attributed to the orientational order/disorder process of ClO4− ions. The heat capacities of the complex were measured with the automatic adiabatic calorimeter and the thermodynamic functions [HT-H298.15] and [ST-S298.15] were derived in the temperature range from 80 to 390 K with temperature interval of 5 K. Thermal decomposition behavior of the complex in nitrogen atmosphere was studied by thermogravimetric (TG) analysis and differential scanning calorimetry (DSC).

Heat capacities and thermodynamic properties of trans-(R)-3-(2,2-dichloroethenyl)-2,2-dimethylcyclopropanecarboxylic acid

The heat capacities of trans-(R)-3-(2,2-dichloroethenyl)-2,2-dimethylcyclopropanecarboxylic acid in the temperature range from 78 to 389 K were measured with a precise automatic adiabatic calorimeter. The sample was prepared with the purity of 0.9874 mole fraction. A solid-liquid fusion phase transition was observed in the experimental temperature range. The melting point, Tm, enthalpy and entropy of fusion, fusHm, fusSm, were determined to be 344.750.02 K, 13.750.07 kJ mol -1 , 39.880.21 J K -1 mol -1 , respec- tively. The thermodynamic functions of the sample, H(T)-H(298.15), S(T)-S(298.15) and G(T)-G(298.15), were reported with a temperature interval of 5 K. The thermal decomposition of the sample was studied by TG analysis, the thermal decomposition starts at ca. 421 K and terminates at ca. 535 K, the maximum decomposition rate was obtained at 525 K. The order of reaction, pre-exponential factor and activation energy, are n=0.14, A=1.15·10 8 min -1 , E=66.27 kJ mol -1 , respectively.