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BaZrO3 and PbZrO3 are both technologically important functional materials particularly with attracting paraelectric and antiferroelectric properties, respectively. However, the current heat capacity studies on these two compounds are insufficient to understand their intrinsic chemical or physical property on thermodynamics. Herein, we reported heat capacities of BaZrO3 and PbZrO3 measured using a relaxation calorimeter equipped on the Physical Property Measurement System in the temperature range from (1.9 to 300) K. The heat capacity data was fitted to a series of theoretical and empirical models, and the corresponding thermodynamic functions were calculated in the range from (0 to 300) K. The heat capacity contributions were extracted using the theoretical model and fitting parameters, revealing that the unusual large heat capacity of BaZrO3 compared with that of PbZrO3 below about 2.5 K is likely due to the dominant linear heat capacity contribution. Also, the heat capacity of BaZrO3 was compared with those previously reported in literate, and most importantly, the heat capacity of PbZrO3 is the first time reported in the temperature region from (40 to 300) K in this work, as far as we know.

A heptanuclear trigonal prismatic polyhedron, [EuCu6(μ-OH)3(Gly)6Im6](ClO4)6·3H2O, was synthesized and characterized by elemental analysis and X-ray single-crystal diffraction. The complex crystallize is the rhombohedral R3 space group (a = b = 15.8673 A, c = 23.4038 A, V = 5103.0(6) A3, Z = 3). In the clusters, Eu3+ ions are situated in the center of a prism formed by six copper atoms and coordinate to nine oxygen atoms with a tricapped trigonal prismatic coordination polyhedron. Six glycinato ligands and six imidazole terminal ligands (each coordinates to one Cu2+) were used in the construction of the cluster. The low-temperature molar heat capacity, C p,m, and thermodynamic properties of the complex were studied with an adiabatic calorimeter from 80 to 370 K. The thermodynamic functions [H T–H 298.15] and [S T–S 298.15] were derived in the temperature range from 80 to 370 K with a temperature interval of 5 K. The thermal properties of the complex from 300 to 800 K were studied by DSC and TG in nitrogen atmosphere.

Neodymium complex with glycine, Nd(Gly)2Cl3·3H2O, was synthesized and characterized by IR spectra. The thermal stability of the complex was tested through TG and DTG and a possible mechanism of thermal decomposition was proposed. The heat capacities of the complex were measured by using an automated adiabatic calorimeter over the temperature range from T = (80 to 380) K, the thermodynamic functions, [HT − H298.15] and [ST − S298.15], were calculated based on the heat capacity measurements. Two (solid + solid) phase transitions in the ranges of T = (170 to 247) K were observed with the peak temperatures of 184.896 K and 231.217, respectively. The standard molar enthalpy of formation of [Nd(Gly)2Cl3·3H2O] was determined to be (−3081.3 ± 1.1) kJ · mol−1 in terms of an isoperibol solution-reaction calorimeter.

The complex of pyridine 2,6-dicarboxylate with Ba2+ ion Ba(HDPC)(2)center dot 2H(2)O(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 360 K 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) kJ mol(-1) by the Hess thermochemical cycle. Furthermore, the reliability of the designed thermochemical cycle was verified by UV-vis spectroscopy. (C) 2013 Elsevier B.V. All rights reserved.

Copper pyridine 2,6-dicarboxylate trihydrate (Cu(H2DPC)(DPC)center dot 3H(2)O) 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 298.15 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. Eventually, the standard molar enthalpy of formation of the title complex was calculated as -(2389.92 +/- 2.53) kJ mol(-1) by the Hess thermochemical cycle. In addition, the reliability of the designed thermochemical cycle was verified by UV-vis spectroscopy. (C) 2013 Elsevier B.V. All rights reserved.

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).

Low-temperature heat capacities of gramine (c11h14n2) were measured by a precision automated adiabatic calorimeter over the temperature range from 78 to 401 k. a polynomial equation of heat capacities as a function of temperature was fitted by least squares method. based on the fitted polynomial, the smoothed heat capacities and thermodynamic functions of the compound relative to the standard reference temperature 298.15 k were calculated and tabulated at 5 k intervals. the constant-volume energy of combustion of the compound at t=298.15 k was measured by a precision oxygen-bomb combustion calorimeter as delta(c)u=-(35336.7 +/- 13.9) j center dot g-1. the standard molar enthalpy of combustion of the compound was determined to be ?chm0=-(6163.2 +/- 2.4) kj center dot mol-1, according to the definition of combustion enthalpy. finally, the standard molar enthalpy of formation of the compound was calculated to be;chm0=-(166.2 +/- 2.8) kj center dot mol-1 in accordance with hess law.

The heat capacities of N-(tert-butoxycarbonyl)-l-phenylalanine (abbreviated to NTBLP in this article), as an important chemical intermediates used to synthesize proteins and polypeptides, were measured by means of a fully automated adiabatic calorimeter over the temperature range from 78 to 350 K. The measured experimental heat capacities were fitted to a polynomial equation as a function of temperature. The thermodynamic functions, H T − H 298.15K and S T − S 298.15K, were calculated based on the heat capacity polynomial equation in the temperature range of (80–350 K) with an interval of 5 K. The thermal stability of the compound was further studied using TG and DSC analyses; a possible mechanism for thermal decomposition of the compound was suggested.

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.

An n-butanol-based nanofluid containing nanowire-shaped β-FeOOH was synthesized by a solvothermal method. The nanofluid was stable for 7 days without any precipitation with 3.0 mM SDBS as stabilizer. Uniform β-FeOOH nanowires with high aspect ratios were fabricated. The heat capacities of the obtained β-FeOOH sample, the base fluid, and the nanofluid were determined by an adiabatic calorimeter. 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 based on the fitted polynomials and the relationships of the thermodynamic functions. These results are very useful to apply to the as-produced nanowire-shaped β-FeOOH and the nanofluid in engineering fields.

Two sulfonate-containing zwitterions, 1-methylimidazolium-3-propylsulfonate zwitterion (MimC(3)SO(3), C(7)H(12)N(2)O(3)S; CAS 179863-07-1) and 1-methylimidazolium-3-butylsulfonate zwitterion (MimC(4)SO(3); C(8)N(14)O(3)S; CAS 148019-49-2), were prepared, and the structures were characterized by (1)H NMR and (13)C NMR and ESI-MS. The thermodynamic properties are investigated through adiabatic caloremetry (AC). differential scanning calorimetry (DSC). and thermogravimetric (TG) analysis. The low-temperature heat capacity (C(p,m)) of MimC(3)SO(3) and MimC(4)SO(3) was measured in the temperature range from (78 to 400) K with a high precision automated calorimeter. The thermodynamic functions [H(T) - H(298.15)] and [S(T) - S(298.15)] were calculated based on the heal capacity data in the range from (80 to 400) K with an interval of 5 K.

Rare earth elements have been widely used in many areas. Rare earth complex bearing an amino acid was synthesized to study the influence and the long-term effect of rare earth elements on environment and human beings, because amino acid is the basic unit of the living things. Previous work on these kinds of complex is focused on synthesis and characterization of them. But their thermodynamic data have seldom been reported. Here we present the thermodynamic study of [ Ho (Thr) (H2O)(5)] Cl-3. The heat capacity of Holmium complex with threonine, [ Ho (Thr) ((HO)-O-2)(5)] Cl-3, was measured with an automatic adiabatic calorimeter in the temperature range from 79 K to 330 K and no thermal anomaly was found in this range. Thermodynamic functions relative to standard state 298.15 K were derived from the heat capacity data. Thermal decomposition behavior of the complex in nitrogen atmosphere in the range from 300 K to 900 K was studied by thermogravimetric (TG) technique and a possible decomposition mechanism was proposed according to the TG-DTG results.

The molar heat capacity of the azeotropic mixture composed of water and benzene was measured by an adiabatic calorimeter in the temperature range from 80 to 320 K. The phase transitions took place in the temperature range from 265.409 to 275.165 K and 275.165 to 279.399 K. The phase transition temperatures were determined to be 272.945 and 278.339 K, which were corresponding to the solid-liquid phase transitions of water and benzene, respectively. The thermodynamic functions and the excess thermodynamic functions of the mixture relative to standard temperature 298.15 K were derived from the relationships of the thermodynamic functions and the function of the measured heat capacity with respect to temperature.

The ethylenediammonium tetrachlorozincate chloride (C2H10N2)2(ZnCl4)Cl2 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.

A coordination compound, ethylenediammonium tetrachlorocobaltate(II) chloride (H3NCH2CH2NH3)(2)[CoCl4]Cl-2, 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 Delta H-r(m)o = (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 Delta H-f(m)o {(NH3CH2CH2NH3)(2)[CoCl4]Cl-2, s} = (1499.54 +/- 2.73) kJ.mol(-1) in accordance with Hess's law.

The crystal structure and composition of (C12H25NH3)(2)ZnCl4(s) were characterized by chemical and elemental analysis. X-ray powder diffraction technique and X-ray crystallography. The lattice energy of the title compound was calculated to be U-POT=888.82 kJ.mol(-1). Low temperature heat capacities of the title compound have been measured by a precision automated adiabatic calorimeter over the temperature range from 80 to 403 K. An obvious solid to solid phase transition occurred in the heat capacity curve, and the peak temperature, molar enthalpy and molar entropy of the phase transition of the compound were determined to be T-trs=(364.02 +/- 0.03) K, Delta H-trs(m) = (77.567 +/- 0.341) kJ.mol(-1), and Delta S-trs(m)=(213.77 +/- 1.17) J.K-1.mol(-1), respectively. Experimental molar heat capacities before and after the phase transition were respectively fitted to two polynomial equations. The smoothed molar heat capacities and fundamental thermodynamic functions of the sample relative to the standard reference temperature 298.15 K were calculated and tabulated at an interval of 5 K.

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.

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.

Heat capacities of the rare-earth complex with glycine [Ho(Gly)3Cl3 · 3H2O] 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, (HT—H298.15) and (ST—S298.15), were calculated.

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...

1-Dodecylamine hydrochloride was synthesized by the solvent-thermal method. The structure and composition of the compound were characterized by chemical and elemental analyses, the X-ray powder diffraction technique, and X-ray crystallography. The main structure and performance of an improved automated adiabatic calorimeter are described. Low-temperature heat capacities of the title compound are measured by the new adiabatic calorimeter over the temperature range from 78 K to 397 K. Two solid-to-solid phase transitions have been observed at the peak temperatures of (330.78 ± 0.43) K and (345.09 ± 0.16) K. The molar enthalpies of the two phase transitions of the substance were determined to be (25.718 ± 0.082) kJ · mol−1 and (5.049 ± 0.055) kJ · mol−1, and their corresponding molar entropies were calculated as (77.752 ± 0.250) J · mol−1 · K−1 and (14.632 ± 0.159) J · mol−1 · K−1, respectively, based on the analysis of heat–capacity curves. Experimental values of heat capacities for the title compound have been fitted to two polynomial equations. In addition, two solid-to-solid phase transitions and a melting process of C12H25NH3Cl(s) have been verified by differential scanning calorimetry.

Different morphologies of beta-FeOOH including rod- and spindle-shaped crystals were synthesized via a hydrothermal reaction at low temperature. The molar heat capacities of the obtained samples were determined by a precision automated adiabatic calorimeter over the temperature range of (78 to 390) K. The observed results demonstrated that the change of the molar heat capacity with thermodynamic temperature was different for the rod and spindle-shaped beta-FeOOH crystals. Polynomial equations of the molar heat capacities as a function of temperature were fitted by a least-squares method for the rod- and spindle-shaped beta-FeOOH crystals. Smoothed heat capacities and thermodynamic functions of the obtained samples, such as H(T/K) - H(298.15) and S(T/K) - S(298.15), were Calculated on the basis of the fitted polynomials and the relationships of the thermodynamic functions. In addition, the as-prepared samples were also characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), and thermal gravimetric analysis (TGA).

The low-temperature heat capacity Cp,m of d-mannitol was measured in the temperature range from (80 to 390) K by means of a fully automated adiabatic calorimeter. The dependence of heat capacity on the temperature was fitted to a polynomial equation with the least-squares method. The thermodynamic functions (HT − H298.15 K) and (ST − S298.15 K) were derived from the heat capacity data in the temperature range of (80 to 390) K with an interval of 5 K. The melting temperature, molar enthalpy, and entropy of fusion were determined to be (437.25 ± 0.12) K, (54.69 ± 1.64) kJ·mol−1, and (125.08 ± 3.75) J·K−1·mol−1 by DSC measurements. The thermal stability and nonisothermal thermal decomposition kinetics of the compound were studied by the TG-DTG technique under atmospheric pressure and flowing nitrogen gas conditions. The thermal decomposition process had one mass loss stage, and the apparent activation energy Ea was obtained to be (120.61 ± 1.85) kJ·mol−1 by the Kissinger, Friedman, and Flynn−Wall−Ozawa metho...

A 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.

A novel and facile method for preparation of stable nanofluid is introduced, in which fecl(3)center dot 6h(2)o and urea were used as reactants without any surfactants. the obtained solid sample was proved to be beta-feooh by xrd technology and spindle-shaped by tem technology. the coexisting nh(3) molecules may be the main reason for the stable nanofluid. the weak bonding between nitrogen and iron atoms would be formed. the investigation on the excess heat capacity of the obtained nanofluid sustains this opinion. the heat capacities of the obtained beta-feooh particles and the nanofluid were determined by an adiabatic calorimeter. and these obtained results will help the applications of beta-feooh and the nanofluid to industry, and the establishment of the model of thermal conductivity of nanofluid. the thermodynamic properties of the obtained beta-feooh particles and the nanofluid were calculated based on the obtained functions of heat capacity with respective to thermodynamic temperature and the relationships between the thermodynamic properties.

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 C6H5COONa (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.

Benzoic acid and barium hydroxide octahydrate were used as reactants, and a compound Ba(C7H5O2)2(s) was synthesized by the method of hydrothermal reaction. Chemical and elemental analyses, FTIR, and X-ray powder diffraction 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 (77 to 402) 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 on the basis of the fitted polynomial. The enthalpy change of the reaction of benzoic acid with barium hydroxide octahydrate was determined to be (22.03 ± 0.30) kJ·mol−1 by respective measuring enthalpies of dissolution of benzoic acid and Ba(C7H5O2)2(s) in 0.1 mol·dm−3 HCl and barium hydroxide octahydrate in 0.1 mol·dm−3 HCl solution containing certai...

Molar heat capacities of 4-(aminomethyl)benzoic acid were precisely measured with a small sample precision automated adiabatic calorimeter over the temperature range from 80 to 400 K, and the heat capacity data were fitted to a polynomial equation: C(p,m) = 162.01+91.771X+6.4372X(2)+1.7517X(3)-4.991X(4)+8.909X(5)+1.585X(6), X = (T235)/155. The constant-volume energy of combustion of the compound was measured by means of a precision oxygen bomb combustion calorimeter. The standard enthalpy values of combustion and formation were determined to be: Delta(c)H(m)(circle minus) = -(4300 +/- 4) kJ.mol(-1) and Delta(f)H(m)(circle minus) = -(420 +/- 5) kJ.mol(-1).

Low-temperature molar heat capacities of the carbon nanotubes (CNTs) including single-walled carbon nanotubes (SWNTs) and multiwalled carbon nanotubes (MWNTs) were measured, respectively, by a precision automated adiabatic calorimeter over the temperature range of (78 to 398) K. The observed results demonstrated that the change in the molar heat capacity with thermodynamic temperature was different for the SWNTs and the MWNTs. Polynomial equations of the molar heat capacities as a function of the temperature were fitted by the least-squares method for SWNTs and MWNTs, respectively. Smoothed heat capacities and the changes in thermodynamic functions of the CNTs, such as ΔH = H(T/K) − H(298.15) and ΔS = S(T/K) − S(298.15), were calculated on the basis of the fitted polynomials and the relationships of the thermodynamic functions.

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.

A novel compound, anhydrous calcium nicotinate Ca(Nic)2(s) (Nic = nicotinate), was synthesized by the method of room-temperature solid phase synthesis. FTIR, chemical, and elemental analyses and an X-ray powder diffraction technique were applied to characterize the structure and composition of the complex. 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 regions of (78 ∼ 400) K were fitted to one polynomial. The polynomial fitted values of the molar heat capacities and fundamental thermodynamic functions of the sample relative to the standard reference temperature 298.15 K were calculated and tabulated at intervals of 5 K. In accordance with Hess’ law, a thermochemical cycle was designed; the enthalpy change of the solid phase reaction of nicotinic acid with calcium hydroxide was determined to be Δ...

The low-temperature heat capacity c(p,m) of 2-methyl-2-butanol was precisely measured in the temperature range from 80 to 305 k by means of a small sample automated adiabatic calorimeter. three solid-solid phase transitions and one solid-liquid phase transition were found at t = 146.355, 149.929, 214.395 and 262.706 k from the experimental c(p)-t curve, respectively. the dependence of heat capacity on temperature was fitted to the following polynomial equations with a least square method. in the temperature range of 80 to 140 k, c(p,m)=39.208+8.0724x-1.9583x(2)+10.06x(3)+1.799x(4)-7.2778x(5)+1.4919x(6),x=(t-110)/30; in the temperature range of 155 to 210 k, c(p,m) = 70.701+10.631x+12.767x(2)+0.3583x(3)-22.272x(4)-0.417x(5)+ 12.055x(6), x=(t-182.5)/27.5; in the temperature range of 220 to 250 k, c(p,m)= 99.176+7.7199x-26.138x(2)+28.949x(3)+0.7599x(4)-25.823x(5)+21.131x(6),x =(t-235)/15; and in the temperature range of 270 to 305 k, c(p,m)= 121.73+ 16.53x-1.0732x(2)-34.937x(3)-19.865x(4)+24.324x(5)+18.544x(6), x=(t- 287.5)/17.5. the molar enthalpies of these transitions were determined to be 0.9392, 1.541, 0.6646 and 2.239 kj center dot mol(-1), respectively. the molar entropies of these transitions were determined to be 6.417, 10.28, 3.100 and 8.527 j center dot k(-1)center dot mol(-1), respectively. the thermodynamic functions [h(t)-h(298.15)] and [s(t)-s(298.15)], were derived from the heat capacity data in the temperature range of 80 to 305 k with an interval of 5 k.

The heat capacities of (3,4-dimethoxyphenyl) acetonitrile were measured by a small sample precision automated adiabatic calorimeter over the temperature range from (78 to 399) K. A melting phase tr...

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 m...

Low-temperature heat capacities of the solid coordination compound trans-Cu(Gly)2·H2O(s) were measured by a precision automated adiabatic calorimeter over the temperature range from T = 78 K to T = 381 K. The initial dehydration temperature of the coordination compound was determined to be TD = 329.50 K, by analysis of the heat-capacity curve. The experimental values of the molar heat capacities in the temperature region of 78−328 K 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 complex trans-Cu(Gly)2·H2O(s) were calculated based on the fitted polynomial. The smoothed values of the molar heat capacities and fundamental thermodynamic functions of the sample relative to the standard reference temperature 298.15 K were tabulated with an interval of 5 K. Enthalpies of dissolution of {Cu(Ac)2·H2O(s) + 2Gly(s)} [ΔsHmϑ (1)] and HAc(l) [ΔsHmϑ (2)] in 100.0...

A fully automated adiabatic calorimeter controlled on line by a computer used for heat capacity measurements in the temperature range from 80 to 400 K was constructed. The hardware of the calorimetric system consisted of a Data Acquisition/Switch Unit, 34970A Agilent, a 7 1/2 Digit Nano Volt /Micro Ohm Meter, 34420A Agilent, and a P4 computer. The software was developed according to modern controlling theory. The adiabatic calorimeter consisted mainly of a sample cell equipped with a miniature platinum resistance thermometer and an electric heater, two (inner and outer) adiabatic shields, two sets of six junction differential thermocouple piles and a high vacuum can. A Lake Shore 340 Temperature Controller and the two sets of differential thermocouples were used to control the adiabatic conditions between the cell and its surroundings. The reliability of the calorimeter was verified by measuring the heat capacities of synthetic sapphire (α-Al2O3), Standard Reference Material 720. The deviation of the data obtained by this calorimeter from those published by NIST was within ±0.1% in the temperature range from 80 to 400 K.

The low-temperature heat capacities of 1-hexadecanol have been measured with an automatic adiabatic calorimeter over the temperature range from 80 to 370 K. A solid-liquid phase transition was observed at T-m=322.225 +/- 0.002 K and the molar enthalpy and entropy of fusion were determined to be 57.743 +/- 0.008 kJ mol(-1) and 179.19 +/- 0.04 J K-1 mol(-1), respectively. The purity, the real melting point (T-1) and the ideal melting point without any impurity or absolutely purity (To) of the sample under investigation were determined to be 99.162 mol%, 322.21 and 322.34 K, respectively, by fractional melting method. According to the polynomial equation of heat capacity and thermodynamic relationship, the thermodynamic functions of the compound relative to the reference temperature 298.15 K were calculated in the temperature ranges of 80 to 370 K with an interval of 5 K. In addition, further researches of thermal properties for this compound were carried out by means of TG/DTG.

Low-temperature heat capacities of l-3-(3,4-dihydroxyphenyl) alanine (C9H11NO4) were measured by a precision automated adiabatic calorimeter over the temperature range from (78 to 400) K. A polynomial equation of heat capacities as a function of temperature was fitted by the least-squares method. Based on the fitted polynomial, the smoothed heat capacities and thermodynamic functions of the compound relative to the standard reference temperature 298.15 K were calculated and tabulated at 5 K intervals. The constant-volume energy of combustion of the compound at T = 298.15 K was measured by a precision oxygen-bomb combustion calorimeter to be ΔcU = −(21183.5 ± 35.0) J·g−1. The standard molar enthalpy of combustion of the compound was determined to be ΔcH°m = −(4177.8 ± 6.9) kJ·mol−1, according to the definition of combustion enthalpy. Finally, the standard molar enthalpy of formation of the compound was calculated to be ΔfH°m = −(935.9 ± 7.0) kJ·mol−1 in accordance with Hess law.

Low-temperature heat capacities of the solid coordination compound Cr(C6H4NO2)3(s) have been measured by a precision automated adiabatic calorimeter over the temperature range T = 78 K to T = 391 K. The experimental values of the molar heat capacities in the temperature region 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 complex Cr(C6H4NO2)3(s) were calculated based on the fitted polynomial. The smoothed values of the molar heat capacities and fundamental thermodynamic functions of the sample relative to the standard reference temperature 298.15 K are tabulated with an interval of 5 K. Enthalpies of dissolution of {3C6H5NO2(s)} [ΔdHm⊖(1)] and Cr(C6H4NO2)3(s) [ΔdHm⊖(3)] in 100.00 mL of 0.1 mol·dm−3 HCl and {Cr(OH)3(s)} [ΔdHm⊖(2)] in 100.00 mL of 0.1 mol·dm−3 HCl solution containing certain amounts of nicotinic acid (named as solution A1) at T = 29...

Low-temperature heat capacity C-p.m of 2-amino-5-nitropyridine (C5H5N3O2; CAS 4214-76-0) was measured in the temperature range from 80 to 396 K with a high precision automated adiabatic calorimeter. No phase transition or thermal anomaly was observed in this range. The thermodynamic functions [HT - H298.1-5] and [S-T - S-298.15] were calculated in the range from 80 to 395 K based on the heat capacity data. The standard molar energy and standard molar enthalpy of combustion have been determined, Delta U-c (C5H5N3O2, s) = -(2676.26 +/- 0.24) U mol(-1) and Delta H-c(m)degrees (C5H5N3O2, s) = -(2673.16 +/- 0.24) U mol(-1), by means of a precision oxygen-bomb combustion calorimeter at T= 298.15 +/- 0.001 K. The standard molar enthalpy of formation has been derived, Delta H-f(m)degrees, (C5H5N3O2, s) = -(8.97 +/- 0.99) kJ mol(-1), from the standard molar enthalpy of combustion in combination with other auxiliary thermodynamic quantities through a Hess thermochemical cycle. The thermodynamic properties were further investigated through differential scanning calorimeter (DSC) and the thermogravimetric (TG) analysis. (C) 2007 Elsevier B.V. All rights reserved.

the heat capacities of artemisinin in crystal form were measured in the temperature range from 80 to 363 k by an adiabatic calorimeter. three thermal anomalies were observed at 198, 240, and 312 k. thermogravimetry and differential thermal analysis from 300 to 700 k showed melting at 420 k, loss of formic acid at 480 k, and further decomposition above 480 k. (c) 2007 elsevier b.v. all rights reserved.

Disodium hydrogen phosphate dodecahydrate (Na2HPO4 center dot 12H(2)O) is an attractive candidate for phase change materials. The main problem for its practical use comes from incongruent melting character during thermal cycling. Experimentally, heat of fusion of the pure salt decreased from 200 to 25 J center dot g (-1) in a four-run freeze-thaw cycling. Additives such as thickening agent or in-situ synthesized polyacrylate sodium in the molten salt can prevent its phase separation to some extent. In the test, sodium alginate 3.0% - 5.0% (w/w) thickened mixture containing Na2HPO4 center dot 12H(2)O and some water showed constant heat storage capacities. Polyacrylate sodium gelled salt was synthesized through polymerizing sodium acrylate in the melt of Na2HPO4 center dot 12H(2)O and some extra water at 50 degrees C. Optimum conditions composed of sodium acrylate 3.0%-5.0% (w/w), cross-linking agent N,N-methylenebis-acrylamide 0.10%-0.20% (w/w), K2S2O8 and Na2SO3 (mass ratio 1 : 1) 0.06%-0.12% (w/w). As opposed to normal large, crystals of pure Na2HPO4 center dot 12H(2)O in solid state, the gelled salt existed in a large number of tiny particles dispersed in the gel network at room temperature, commonly less than 2 mm. But only those sample particles with sizes less than 0.2 mm may have relatively stable thermal storage property. A problem encountered was the poor reproducibility of the synthesis method: heat storage capacity of the product was often very different even though the synthesis was carried out in the same conditions. An alternative gelling method by sodium alginate Grafted sodium acrylate was tried and it showed a fairly good effect. Heat capacities and heat of fusion of Na2HPO4 center dot 12H(2)O were measured by an adiabatic calorimeter.

The low-temperature heat capacity C p , m 0 of xylitol was precisely measured in the temperature range from 80 to 390 K by means of a small sample automated adiabatic calorimeter. A solid–liquid phase transition was found from the experimental Cp–T curve in the temperature range 360–375 K with the peak heat capacity at 369.04 K. The dependence of heat capacity on the temperature was fitted to the following polynomial equations with least square method. In the temperature range of 80–360 K, C p , m 0 ( J K − 1 mo l − 1 ) = 165.87 + 105.19 x + 1.8011 x 2 − 41.445 x 3 − 41.851 x 4 + 65.152 x 5 + 66.744 x 6 , x = [ T ( K ) − 220 ] / 140 . In the temperature range of 370–390 K, C p , m 0 ( J K − 1 mo l − 1 ) = 426.19 + 5.6366 x , x = [ T ( K ) − 380 ] / 10 . The molar enthalpy and entropy of this transition were determined to be 33.26 ± 0.17 kJ mol−1 and 90.12 ± 0.45 J K−1 mol−1, respectively. The standard thermodynamic functions ( H T 0 − H 298.15 0 ) and ( S T 0 − S 298.15 0 ) , were derived from the heat capacity data in the temperature range of 80 to 390 K with an interval of 5 K. The standard molar enthalpy of combustion and the standard molar enthalpy of formation of the compound have been determined, Δ c H m 0 (C5H12O5, cr) = (−2463.2 ± 1.2) kJ mol−1and Δ f H m 0 (C5H12O5, cr) = (−1219.3 ± 0.3) kJ mol−1, by means of a precision oxygen bomb combustion calorimeter at T = 298.15 K. DSC and TG measurements were performed to study the thermal stability of the compound. The results were in agreement with those obtained from heat capacity measurements.

The fast mixing of aqueous solutions of calcium chloride and sodium carbonate resulted in crystalline forms of vaterite and calcite under vigorous stirring. Then, the vaterite was transformed to pure calcite within about 180 min. The crystalline forms all grew with experimental time increase. Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), and X-ray diffraction spectroscopy (XRD) techniques were employed to characterize the as-prepared samples. The heat capacity of the stable as-synthesized calcite was determined by means of an adiabatic calorimeter from 80 to 390 K. The thermodynamic functions of the calcite were derived based on the relationships among the thermodynamic functions and the function of the measured heat capacity with respect to temperature.

The thermodynamic properties of 2-pyridinealdoxime were investigated through the thermogravimetric (TG) analysis and differential scanning calorimetry (DSC). Low-temperature heat capacity Cp,m of 2-pyridinealdoxime (C6H6N2O; CAS 873-69-8) was measured in the temperature range from (80 to 373) K with a high precision automated adiabatic calorimeter. No phase transition or thermal anomaly was observed in this range. The thermodynamic functions [HT − H298.15] and [ST − S298.15] were calculated in the range from (80 to 375) K. The constant-volume energy and standard molar enthalpy of combustion have been determined, Δ c U ( C 6 H 6 N 2 O,cr ) = Δ c H m ∘ (C6H6N2O, cr) = − (3297.11 ± 1.53) kJ · mol−1 (based on Δn being zero in reaction of the combustion), by means of a precision oxygen-bomb combustion calorimeter at T = (298.15 ± 0.001) K. The standard molar enthalpy of formation has been derived, Δ f H m ∘ (C6H6N2O, cr) = (78.56 ± 2.43) kJ · mol−1, from the standard molar enthalpy of combustion in combination with other auxiliary thermodynamic quantities through a Hess thermochemical cycle.

The constant-volume energy of combustion of crystalline anhydrous caffeine (C8H10N4O2) in α (lower temperature steady) crystal form was measured by a bomb combustion calorimeter, the standard molar enthalpy of combustion of caffeine at T = 298.15 K was determined to be −(4255.08 ± 4.30) kJ · mol−1, and the standard molar enthalpy of formation was derived as −(322.15 ± 4.80) kJ · mol−1. The heat capacity of caffeine in the same crystal form was measured in the temperature range from (80 to 387) K by an adiabatic calorimeter. No phase transition or thermal anomaly was observed in the above temperature range. The thermal behavior of the compound was further examined by thermogravimetry (TG), differential thermal analysis (DTA) over the range from (300 to 700) K and by differential scanning calorimetry (DSC) over the range from (300 to 540) K, respectively. From the above thermal analysis a (solid–solid) and a (solid–liquid) phase transition of the compound were found at T = (413.39 and 509.00) K, respectively; and the corresponding molar enthalpies of these transitions were determined to be (3.43 ± 0.02) kJ · mol−1for the (solid–solid) transition, and (19.86 ± 0.03) kJ · mol−1 for the (solid–liquid) transition, respectively.

Low-temperature heat capacity Cp,m of 2,6-dicarboxypyridine (C7H5NO4; CAS 499-83-2) was precisely measured in the temperature range from (80 to 378) K with a high precision automated adiabatic calorimeter. No phase transition or thermal anomaly was observed in this range. The thermodynamic functions [HT − H298.15] and [ST − S298.15] were calculated in the range from (80 to 378) K. The standard molar enthalpy of combustion and the standard molar enthalpy of formation of the compound have been determined, Δ c H m ∘ ( C 7 H 5 NO 4 , cr ) = - ( 2741.41 ± 0.49 ) kJ · mol - 1 and Δ f H m ∘ ( C 7 H 5 NO 4 , cr ) = - ( 727.74 ± 1.50 ) kJ · mol - 1 , by means of a precision oxygen-bomb combustion calorimeter at T = 298.15 K. The thermodynamic properties of the compound were further investigated through differential scanning calorimeter (DSC) and the thermogravimetric (TG) analysis.

Molar heat capacities of the pure samples of acetone, methanol and the azeotropic mixture composed of acetone, cyclohexane and methanol were measured by an adiabatic calorimeter from 78 to 320 k. the solid-solid and solid-liquid phase transitions of the pure samples and the mixture were determined based on the curve of the heat capacity with respect to temperature. the phase transitions took place at (126.16 +/- 0.68) and (178.96 +/- 1.47) k for the sample of acetone, (157.79 +/- 0.95) and (175.93 +/- 0.95) k for methanol, which were corresponding to the solid-solid and the solid-liquid phase transitions of the acetone and the methanol, respectively. and the phase transitions occurred in the temperature ranges of 120 to 190 k and 278 to 280 k corresponding to the solid-solid and the solid-liquid phase transitions of mixture of acetone, cyclohexane and methanol, respectively. the thermodynamic functions and the excess thermodynamic functions of the mixture relative to standard temperature of 298.15 k were derived based on the relationships of the thermodynamic functions and the function of the measured heat capacity with respect to temperature.

The molar heat capacities of the room temperature ionic liquid 1-ethyl-3-methylimidazolium ethyl sulfate (EMIES) were measured by an adiabatic calorimeter in temperature range from 78 to 390 K. The dependence of the molar heat capacity on temperature was given as a function of the reduced temperature X by polynomial equations, Cp,m (J K−1 mol−1) = 178.6 + 50.28X + 2.886X2 − 1.362X3 + 0.6616X4 + 7.155X5 [X = (T − 132.5)/54.5] for the solid phase (78–187 K) and Cp,m (J K−1 mol−1) = 376.2 + 25.94X − 3.397X2 − 0.6407X3 + 0.8091X4 + 0.9869X5 [X = (T − 292.5)/97.5] for the liquid phase (195–390 K), respectively. According to the polynomial equations and thermodynamic relationship, the values of thermodynamic function of the EMIES relative to 298.15 K were calculated in temperature range from 80 to 390 K with an interval of 5 K. The glass translation of EMIES was observed at 192.85 K. Using oxygen-bomb combustion calorimeter, the molar enthalpy of combustion of EMIES was determined to be Δ c H m ° = − 5152.6 ± 4.6 kJ mo l − 1 . The standard molar enthalpy of formation of EMIES was evaluated to be Δ f H m ° = − 579.13 ± 0.51 kJ mo l − 1 at T = 298.150 ± 0.001 K.

The molar heat capacity, C-p,C-m, of a complex of erbium chloride coordinated with L-proline, [Er(Pro)(2)(H2O)(5)]Cl-3, was measured from T) 80 K to T) 400 K with an automated adiabatic calorimeter. The temperature, the molar enthalpy, and the entropy of fusion and decomposition were calculated using equations and diagrammatic area integration. The thermodynamic functions [H-T-H-298.15] and [S-T-S-298.15] were derived from T = 80 K to T = 360 K with a temperature interval of 5 K. The thermal stability of the compound was investigated by differential scanning calorimetry and the thermogravimetric techniques.