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n-Alkanes have been widely used as phase change materials (PCMs) for thermal energy storage applications because of their exceptional phase transition performance, high chemical stability, long term cyclic stability and non-toxicity. However, the thermodynamic properties, especially heat capacity, of n-alkanes have rarely been comprehensively investigated in a wide temperature range, which would be insufficient for design and utilization of n-alkanes-based thermal energy storage techniques. In this study, the thermal properties of n-alkanes (C18H38-C22H46), such as thermal stability, thermal conductivity, phase transition temperature and enthalpy were systematically studied by different thermal analysis and calorimetry methods, and compared with previous results. Thermodynamic property of these n-alkanes was studied in a wide temperature range from 1.9 to 370 K using a combined relaxation (Physical Property Measurement System, PPMS), differential scanning and adiabatic calorimetry method, and the corresponding thermodynamic functions, such as entropy and enthalpy, were calculated based on the heat capacity curve fitting. Most importantly, the heat capacities and related thermodynamic functions of n-heneicosane and n-docosane were reported for the first time in this work, as far as we know. This research work would provide accurate and reliable thermodynamic properties for further study of n-alkanes-based PCMs for thermal energy storage applications.

Phase change materials (PCMs) generally offer high latent heats for a wide range of thermal energy storage technologies. As typical organic PCMs, polyethylene glycol (PEG) has been widely studied due to their high latent enthalpy, non-toxic and non-corrosive natures. However, the thermal properties especially the heat capacities of PEG, which would play a vital role in theoretically and technically investigating PCM thermal performance, have never been studied in a wide temperature region. Herein, we reported the heat capacities of PEG samples with the molar massvarying from 1000 to 20,000 for the first time in the temperature range from (1.9 to 400) K using a combination method of Physical Property Measurement System (PPMS) and differential scanning calorimeter (DSC). Furthermore, the standard molar heat capacity, entropy and enthalpy at 298.15 K and 0.1 MPa were calculated based on the heat capacity curve fitting. Meanwhile, the phase transition temperature and enthalpy, thermal conductivity and thermal stability of these PEG samples were measured using various thermal analysis methods, and these thermal properties were also compared with the previous results.

Four Zn, Cd and Mn based 1,10-phenanthroline and halogenated benzoic acid coordination compounds, formulated as Zn2II(H2O)3(phen)(SO4)·H2O (1, phen = 1,10-phenanthroline), ZnII(phen)(L2)2(H2O) (2, L2 = 2-chloro-4-fluorobenzoic acid), MnIV(phen)(L1)4 (3, L1 = 2-Chloro-4,5-difluorobenzoic acid) and CdII(phen)2(NO3)2 (4), were successfully synthesized and structurally characterized. The low temperature heat capacities of these four compounds were further investigated using a Physical Property Measurement System calorimetric method. The experimental heat capacities were fitted to a series of theoretical and empirical heat capacity models, and the corresponding thermodynamic functions were calculated in the temperature range from (0 to 300) K based on these models and fitting parameters. The low temperature fits indicated that compound 1 can be modeled using only lattice heat capacity contribution, compound 3 modeled using lattice and A-2 term or Schottky heat capacity contributions, and compound 2 and 4 modeled using contributions from lattice, vacancies and one-dimensional phonons with a finite energy onset or gap.

A new chiral mononuclear iron(II) compound, formulated as {[Fe(ACBP)3]·(ClO4)} (1, ACBP = (S,S)-3,3′-(1,2-dimethylpropanedioxy)-2,2′-bipyridine), has been synthesized and structurally characterized. The magnetic study revealed that compound 1 possesses antiferromagnetic exchange interactions between Fe(II) ions through the hydrogen bonds. The low-temperature heat capacity of compound 1 was measured in the temperature range from 1.9 to 300 K using the heat capacity option of a Quantum Design Physical Property Measurement System (PPMS). Additionally, the thermodynamic functions in the experimental temperature range have been derived by fitting the heat capacity data to a series of theoretical and empirical models. The standard molar heat capacity, entropy and enthalpy of compound 1 at 298.15 K and 0.1 MPa have been determined to be $$C_{\text{p,m}}^{\text{o}}$$ = (1036.9 ± 10.4) J mol−1 K−1, $$S_{\text{m}}^{\text{o}}$$ = (1059.6 ± 10.6) J mol−1 K−1 and $$H_{\text{m}}^{\text{o}}$$ = (160.29 ± 1.60) kJ mol−1, respectively.

Low temperature calorimetry is an experimental method of heat capacity measurements, and heat capacity is one of the most important and fundamental thermodynamic properties of substances. The heat capacity can provide an average evaluation of the thermal property of a sample since it is a bulk property of substances. In the other hand, the condensed states of substances could be mainly controlled by the molecular motions, intermolecular interactions, and interplay among molecular structures. The physical property reflected in a material may be closely related to the energy changes in these three factors, which can be directly observed in a heat capacity curve. Therefore, low temperature calorimetry has been used not only to obtain heat capacity, entropy, enthalpy and Gibbs free energy, but also to investigate and understand lattice vibrations, metals, superconductivity, electronic and nuclear magnetism, dilute magnetic systems and structural transitions. In this review, we have presented the concept of low temperature calorimetry and its applications in the related field of material researches, such as nano-materials, magnetic materials, ferroelectric materials, phase change materials and other materials.

Two novel mononuclear compounds, formulated as [Co(phen)(pae)(H2O)3] ∙ H2O (1) and [Ni(phen)(pae) (H2O)3] ∙ H2O (2) (phen = 1,10-phenanthroline, pae = o-pthalic acid), has been synthesized and structurally characterized. The magnetic measurement revealed that compound 1 and 2 could possess antiferromagnetic exchange interactions between CoII/NiII ions through the hydrogen bonds-bridging. The low temperature heat capacity of compound 1 and 2 were measured using the heat capacity option of a Quantum Design Physical Property Measurement System (PPMS) in the temperature range between (1.9–300) K. The measured heat capacities were fitted to a series of theoretical and empirical models, and the corresponding thermodynamic functions were consequently calculated based on the fitting parameters. Moreover, the heat capacities of these two compounds behave an upturn below 10 K, which could be attributed to the Schottky effect occurring at this low temperature region.

The heat capacities of d-ribose and d-mannose have been studied over the temperature range from 1.9 to 440 K for the first time using a combination of Quantum Design Physical Property Measurement System and a differential scanning calorimeter. The purity, crystal phase and thermal stability of these two compounds have been characterized using HPLC, XRD and TG–DTA techniques, respectively. The heat capacities of d-Mannose have been found to be larger than those of d-ribose due to its larger molecular weight, and the solid–liquid transition due to the sample melting has also been detected in the heat capacity curve. The heat capacities of these two compounds have been fitted to a series of theoretical models and empirical equations in the entire experimental temperature region, and the corresponding thermodynamic functions have been derived based on the curve fitting in the temperature range from 0 to 440 K. Moreover, the phase transition enthalpy and melting temperature of these two compounds have also been determined from the heat flows obtained in DSC measurements.

In recent years, sugar alcohols have attracted much attention due to their remarkable phase change properties for thermal energy storage applications. The thermodynamic properties especially the heat capacities would play a crucial role in theoretically and technically investigating the energy storage performance for sugar alcohols. However, as far as we known, the heat capacities of sugar alcohols have never been studied in a wide temperature region. In this study, we have measured the heat capacities of six sugar alcohols of D-mannitol, Myo-Inositol, xylitol, D-arabinitol, L-arabinitol and erythritol in the temperature range from T = (1.9 to 550) K for the first time using a combination of Physical Property Measurement System and differential scanning calorimeter. Based on the heat capacity curve fitting, the standard molar heat capacity, entropy and enthalpy at 298.15 K and 0.1 MPa, and melting temperature and transition enthalpy in the solid–liquid phase transition region were consequently obtained for these sugar alcohols. Moreover, the heat capacity and phase transition properties obtained in this work were also compared with previous results reported in literature.

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.

Metal-organic coordination compounds have been extensively concerned in recent years due to their attracting chemical and physical properties. However, their thermodynamic properties have not been well investigated compared with the other properties, which would limit understanding their relationship between molecular structure and functional performance from a basic thermodynamic view. In the present work, two crystalline compounds of Co3(BTC)2·12H2O (1) and Ni3(BTC)2·12H2O (2) (BTC = 1,3,5- benzenetricarboxylate) have been designed and synthesized using a solvothermal method. The variable-temperature magnetic susceptibilities of these two compounds have been measured and the results revealed that compounds 1 and 2 possessed antiferromagnetic interaction between CoII/NiII ions. Low temperature heat capacities of these two compounds have been measured using a heat capacity option of Physical Property Measurement System in the temperature range from (1.9 to 300) K, and a Schottky effect has been revealed in the heat capacity curve below 10 K. The experimental heat capacity data have been fitted to a series of theoretical and empirical heat capacity models, and the corresponding thermodynamic functions such as enthalpy and entropy have been calculated in the temperature range from (0–300) K based on these models and fitting parameters. Also, the entire Schottky effect peak has been well presented in the heat capacity curve using these fitted heat capacities. The thermodynamic properties obtained in this work may provide significant thermodynamic basis for further investigating the related functional properties of these two compounds.

We report the results of the study of thermodynamic properties for two difluorooxymethylene-bridged fluorinated liquid crystals. Isobaric heat capacities of the compounds were measured using a Quantum Design Physical Properties Measurement System with heat capacity measurement in the range of 1.9–300 K. Heat capacities of two compounds increased with the temperature increment, and no any thermal anomalies were observed in the whole temperature region, and also the heat capacity values of 5-CCXB(F,F)-F are larger than that of 3-CCXB(F,F)-F due to molecular weight difference even though they are homologs. Standard thermodynamic properties of the liquid crystals were evaluated from the experimental heat capacity temperature dependencies. From the heat capacity results, the standard molar entropies and enthalpies at 298.15 K were determined to be (657.32 ± 6.57), (741.81 ± 7.42) J K−1 mol−1 and (97.17 ± 0.97), (108.89 ± 1.09) kJ K−1 mol−1 for n-CCXB(F,F)-F (n = 3, 5), respectively. Finally, the phase transition sequences and thermodynamical stability of these two fluorinated liquid crystals were performed by differential scanning calorimetry measurements in the temperature range of 253–373 K.

Fatty alcohols (FAs) have been widely studied as typical phase-change materials for their high latent heat, low undercooling, non-toxicity, and low cost in thermal energy storage applications. The thermal properties, especially the heat capacity, play a vital role in designing-related energy storage techniques. However, there are few studies on the thermal properties of FAs systematically investigated in a wide temperature region, which greatly limit their application in thermal energy storage field. In this study, the thermal properties of even-numbered FAs (C12H25OH-C18H37OH), such as thermal stability, thermal conductivity, phase transition temperature, and enthalpy have been systematically investigated using a combination of various thermal analysis and calorimetry methods. The corresponding thermodynamic functions such as the standard molar heat capacity, entropy, and enthalpy at 273.15 K and 0.1 MPa have been calculated based on the heat capacity curve fitting. Most importantly, the heat capacities of 1-tetradecanol and 1-hexadecanol are reported for the first time in the wide temperature range of 1.9–370 K. Furthermore, by fitting the heat capacities of FAs, a function of molar heat capacities (Cp) related to the number of carbon atoms (n) and temperature (T) has been established, which can express the heat capacity of FAs between C12H25OH and C22H45OH reasonably in the temperature region of 50–240 K. This work provides accurate and systematic thermodynamic data of FA samples for the future study on their thermodynamic property and related processing design of thermal energy storage application.

The heat capacities of three difluoromethyleneoxy liquid crystalline compounds (n-BB(F)B(F,F)XB(F,F)-F; n = 3, 4, 5) were measured using a quantum design physical properties measurement system (PPMS) based on a heat-pulse relaxation method in the temperature range from 1.9 to 300 K. The experimental results showed that the heat capacities of these three compounds increased with the temperature increment and none of the thermal anomalies were observed in the entire temperature region; and also the heat capacity values of n-BB(F)B(F,F)XB(F,F)-F (n = 3, 5) are larger than those of 4-BB(F)B(F,F)XB(F,F)-F due to the odd–even carbon effect below 21 K. The standard molar entropies at 298.15 K and 0.1 MPa were determined to be (631.14 ± 6.31), (650.21 ± 6.50), and (697.49 ± 6.97) J K−1 mol−1 for n-BB(F)B(F,F)XB(F,F)-F (n = 3, 4, 5), respectively.

The heat capacities of D-galactose and galactitol were measured on a quantum design physical property measurement system(PPMS) over a temperature range of 1.9―300 K, and the experimental data were fitted to a function of T using a series of theoretical and empirical models in appropriate temperature ranges. The fit results were used to calculate thermodynamic function values, C p,m θ , Δ 0 S m θ , and Δ 0 H m θ from 0 K to 300 K. The standard molar heat capacity, entropy and enthalpy values of D-galactose and galactitol at 298.15 K and 0.1 MPa were determined to be C p,m θ =(227.96±2.28) and (239.50±2.40) J·K−1·mol−1, S m θ = (211.22±2.11) and (230.82±2.30) J·K−1·mol−1 and H m θ = (33.95±0.34) and (36.57± 0.37) kJ/mol, respectively.

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.

Low-temperature heat capacities of butyl 4-hydroxybenzoate have been measured by a high precision automated adiabatic calorimeter over the temperature range from 79 to 399 K. The melting temperature, the molar enthalpy and entropy of the phase transition were determined to be (342.227 ± 0.054) K, (26.122 ± 0.192) kJmol-1and (76.33 ± 0.55) JK-1mol-1.The thermodynamic functions (HT-H298.15K) and (ST-S298.15K) were calculated in the range from 80 to 400 K with the interval of 5 K. The constant-volume energy and standard molar enthalpy of combustion have been determined,cU (C11H14O3,s) =-(5760.30 ± 2.70) kJmol-1andcHm0(C11H14O3, s) =-(5765.26 ± 2.70) kJmol-1, by means of a precision oxygen-bomb combustion calorimeter atT= 298.15 K. The standard molar enthalpy of formation has been derived,fHm0(C11H14O3, s) =-( 564.16 ± 4.41) kJmol-1, from the standard molar enthalpy of combustion in combination with other auxiliary thermodynamic quantities through a Hess thermochemical cycle.

Molar heat capacities (Cp,m) of the ionic liquids (ILs) N-alkylpyridinium hexafluorophosphate [Cnpy][PF6] (n = 2, 3, 5) were measured with a high-precision automated adiabatic calorimeter (AC). The melting temperatures were determined. The molar enthalpy and entropy of phase transition were calculated according to the data obtained of the molar heat capacities by the empirical equation. The polynomial equations of molar heat capacity as a function of the temperature were fitted before and after the phase transition for each IL compounds. The thermodynamic functions (HT − H298.15) and (ST − S298.15) were derived from the molar heat capacity values over the temperature range from (80 to 400) K with an interval of 5 K.

The heat capacity of diethyl acetamidomalonate (DEAM) has been studied using an adiabatic calorimeter in the temperature range from (78 to 395) K. No thermal anomalies were observed in temperature regions from (78 to 344) K and from (375 to 395) K, where the heat capacity data were fit to two polynomial equations. A solid–liquid phase transition was detected in temperatures from (344 to 375) K. The phase transition temperature, enthalpy, entropy and mole fraction purity of this compound were determined to be 368.72 K, 34.3 kJ·mol–1, 93.0 J·K–1·mol–1 and 0.9997(mole fraction), respectively, based on the experimental data in the phase transition region. The thermodynamic functions of DEAM relative to the reference temperature of 298.15 K were derived based on the fitted heat capacity data in the entire experimental region.

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).

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.

An N-tert-butyloxycarbonylated organic synthesis intermediate, (S)-tert-butyl 1-phenylethylcarbamate, was prepared and investigated by means of differential scanning calorimetry (DSC) and thermogravimetry (TG). The molar heat capacities of (S)-tert-butyl 1-phenylethylcarbamate were precisely determined by means of adiabatic calorimetry over the temperature range of 80-380 K. There was a solid–liquid phase transition exhibited during the heating process with the melting point of 359.53 K. The molar enthalpy and entropy of this transition were determined to be 29.73 kJ mol−1 and 82.68 J K−1 mol−1 based on the experimental C p–T curve, respectively. The thermodynamic functions, [ $$ H_{T}^{0} - H_{298.15}^{0} $$ ] and [ $$ S_{T}^{0} - S_{298.15}^{0} $$ ], were calculated from the heat capacity data in the temperature range of 80–380 K with an interval of 5 K. TG experiment showed that the pyrolysis of the compound was started at the temperature of 385 K and terminated at 510 K within one step.

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.

The heat capacities of N-benzyloxycarbonyl-L-3-phenylahmine were measured by means of a fully automated adiabatic calorimeter over the temperature range from (79 to 395) K. A solid liquid phase transition corresponding to the melting process was observed. The temperature, the molar enthalpy, and entropy of the phase transition were determined to be 358.799 K. 31.787 kJ.mol(-1), and 88.594 J.K-1.mol(-1), respectively. The mole fraction purity or the sample used in the adiabatic calorimetric study was determined to be 0.9830 according to the Van't Hoff equation. Two equations of temperature dependence for heat capacities in the solid and liquid state are presented. The thermodynamic functions. (H-T - H-298.15K) and (S-T - S-298.15K). were calculated based on the heat capacity data in the temperature range from (80 to 400) K with an interval of 5 K. The standard molar enthalpies of combustion have been determined to be Delta H-c(m)0(C17H17NO4, s) = -(8308.52 +/- 3.22) kJ.mol(-1), with a precision oxygen-bomb combustion calorimeter at T = 298.15 K. The standard molar enthalpy of formation of the compound has been derived from the enthalpy of combustion, Delta H-f(m)0(C17H17NO4, s) = -(815.05 +/- 0.67) kJ.mol(-1). The thermal stability of Me compound was further studied using TG, and DSC, and a possible mechanism for thermal decomposition was suggested.

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.

The molar heat capacities of three different concentrations of aqueous SrCl2 solutions, 0.1212, 0.4615 and 1.878 mol⋅kg−1, were measured, using a precision automated adiabatic calorimeter in the temperature range from 80 to 320 K. Solid–liquid phase transitions were observed at 272.83, 270.18 and 255.15 K, respectively, for these three solutions. The molar enthalpies and entropies of the phase transitions were evaluated. The experimental heat capacity data were fitted to polynomial equations, and based on the polynomial equations and thermodynamic relationship, the thermodynamic functions relative to 298.15 K, [HT−H298.15 K] and [ST−S298.15 K], of the three solutions were derived in the range of 80 to 320 K with an interval of 5 K.

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.

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.

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...

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).

A novel compound-monohydrated nickel nicotinate was synthesized by the method of room temperature solid phase synthesis and ball grinder. FTIR, chemical and elemental analysis, TG/DTG, and X-ray powder diffraction technique were applied to characterize the structure and composition of the coordination compound. Low-temperature heat capacities of the solid coordination compound have been measured by a precision automated adiabatic calorimeter over the temperature range from 78 to 386 K. A solid-solid phase transition occurred in the temperature range of 328–358 K in the heat capacity curve, and the peak temperature, the molar enthalpy and molar entropy of the phase transition were determined to be Ttrs=(356.759±0.697) K, ΔtrsHm=(13.650±0.408) kJ· mol−1, and ΔtrsSm= (38.279±0.086) J·K−1·mol−1, respectively. The experimental values of the molar heat capacities in the temperature ranges of 78–328 K and 358–386 K were fitted to two polynomials, respectively. 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 the intervals of 5 K.

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.

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...

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.

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...

A calorimetric study and thermal analysis for 8-hydroxyquinoline were performed. The low-temperature heat capacity of this compound was measured with a precise automated adiabatic calorimeter over the temperature range from 78 to 370 K. The melting point T(fus), molar enthalpy Delta(fus)H(m) and molar entropy Delta(fus)S(m) of fusion of this substance were determined to be (345.74 +/- 0.15) K, (13.93 +/- 0.11) kJ center dot mol(-1) and (40.26 +/- 0.33) J center dot K(-1)center dot mol(-1), respectively. The thermodynamic functions of the substance, such as molar enthalpy and entropy of fusion, and thermodynamic functions [H(T)-H(298.15)] and [S(T)-S(298.15)] were derived from two polynomial equations of the experimental molar heat capacities against the reduced temperature fitted by the least square method. The melting temperatures for the sample and the absolutely pure compound have been obtained from fractional melting experiments to be 345.601 and 345.761 K, respectively, and the molar fraction purity of the sample was calculated to be 0.9978 according to the van't Hoff equation. The thermal stability of the compound was further investigated by differential scanning calorimetry (DSC).

A novel compound–monohydrated cupric nicotinate was synthesized by the method of room temperature solid phase reaction and a ball grinder. FTIR, chemical and elemental analyses and X-ray powder diffraction techniques 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 78 to 400 K. A melting process occurred in the temperature range of 326–346 K in the heat capacity curve, and the melting point, molar enthalpy and entropy of the fusion were determined to be Tfus= (341.290±0.873) K, ΔfusHm= (13.582±0.012) kJ·mol−1, ΔfusSm= (39.797±0.067) J·K−1·mol−1. The experimental values of the molar heat capacities in the temperature regions of 78–326 K and 346–400 K were respectively fitted to two polynomial equations. The polynomially 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 an interval of 5 K.

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.