Synthesis,Characterization and Standard Molar Formation Enthalpy of [Sm(C_7H_5O_3)_2(C_4H_6NO_2S)]·2H_2O

[Sm（C7H5O3）2（C4H6NO2S）]·2H2O was synthesized from the reaction of samarium chloride hexahydrate with salicylic acid and thioproline,and characterized by IR,elemental analysis and thermogravimatric analysis.The standard molar enthalpies of the solutions of SmCl3·6H2O（s）,2[C7H6O3（s）],[C4H7NO2S（s）] and [Sm（C7H5O3）2·（C4H6NO2S）·2H2O（s）] in a mixed solvent of absolute ethyl alcohol,dimethyl formamide（DMF） and 3 mol/L HCl were,respectively,determined by calorimetry to be ΔsHm^Θ [SmCl3·6H2O（s）,298.15 K]=（-46.68±0.15） kJ/mol,ΔsHm^Θ [2C7H6O3（s）,298.15 K]=（25.19±0.02） kJ/mol,ΔsHm^Θ [C4H7NO2S（s）,298.15 K]=（16.20±0.17） kJ/mol and ΔsHm^Θ {[Sm（C7H5O3）2（C4H6NO2S）]·2H2O（s）,298.15 K}=（-81.24±0.67） kJ/mol.The enthalpy change of the reaction SmCl3·6H2O（s）＋2C7H6O3（s）＋C4H7NO2S（s）=[Sm（C7H5O3）2（C4H6NO2S）]·2H2O（s）＋3HCl（g）＋4H2O（l） was determined to be ΔrHm^Θ =（123.45±0.71） kJ/mol.From the data in the literature,the standard molar formation enthalpy of [Sm（C7H5O3）2（C4H6NO2S）]·2H2O（s） was estimated to be Δf Hm^Θ {[Sm（C7H5O3）2（C4H6NO2S）]·2H2O（s）,298.15 K}=（-2912.03±3.1） kJ/mol through Hess＇ law.

Low-temperature heat capacities and standard molar enthalpy of formation of pyridine-2,6-dicarboxylic acid

This paper reports that the low-temperature heat capacities of pyridine-2,6-dicarboxylic acid were measured by a precision automatic calorimeter over a temperature range from 78 K to 380 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 intervals of 5 K. The constant-volume energy of combustion of the compound was determined by means of a precision rotating-bomb combustion calorimeter. The standard molar enthalpy of combustion of the compound was derived from the constant-volume energy of combustion. The standard molar enthalpy of formation of the compound was calculated from a combination of the datum of the standard molar enthalpy of combustion of the compound with other auxiliary thermodynamic quantities through a Hess thermochemical cycle.

Standard Molar Enthalpy of Formation of RE(C_5H_8NS_2)_3(C_(12)H_8N_2)

Four solid ternary complexes of RE (C_5H_8NS_2)_3(C_(12)H_8N_2) (RE=Eu, Gd, Tb, Dy) were synthesized in absolute ethanol by rare earth chloride low hydrate with the mixed ligands of ammonium pyrrolidinedi-thiocarbamate (APDC) and 1, 10-phenanthroline·H_2O (o-phen·H_2O) in the ordinary laboratory atmosphere without any cautions against moisture or air sensitivity. IR spectra of the complexes show that the RE^(3+) coordinated with six sulfur atoms of three PDC^- and two nitrogen atoms of o-phen·H_2O. It was assumed that the coordination number of RE^(3+) is eight. The constant-volume combustion energies of the complexes, Δ_cU, were determined as (-16937 88±9 79 ), (-17588 79±8 62 ), ((-17747 14±)8 25 ) and (-17840 37±8 87 ) kJ·mol^(-1), by a precise rotating-bomb calorimeter at 298.15 K. Its standard molar enthalpies of combustion, Δ_cH~θ_m, and standard molar enthalpies of formation, Δ_fH~θ_m, were calculated as (-16953 37±9 79), (-17604 28±8 62), (-17762 63±8 25), (-17855 86±8 87) kJ·mol^(-1) and (-857.04±10.52), (-282.43±9.58), (-130.08±9.13), (-55.75±9.83) kJ·mol^(-1).

Lattice potential energy and standard molar enthalpy in the formation of 1-dodecylamine hydrobromide (1-C_(12)H_(25)NH_3 ·Br)(s)

This paper reports that 1-dodecylamine hydrobromide （1 C12H25NH3.Br）（s） has been synthesized using the liquid phase reaction method. The lattice potential energy of the compound 1-C12H25NH3.Br and the ionic vol- ume and radius of the 1-C12H25NH3＋ cation are obtained from the crystallographic data and other auxiliary ther- modynamic data. The constant-volume energy of combustion of 1 C12H25NH3.Br（s） is measured to be AcUo（1 C12H25NH3.Br, s） = （7369.03-4-3.28） kJ.mo1-1 by means of an RBC-II precision rotating-bomb combustion calorime- ter at T=（298.15~0.001） K. The standard molar enthalpy of combustion of the compound is derived to be △cHo（1- C12H25NH3.Br, s）=- （7384.52±3.28） kJ.mo1-1 from the constant-volume energy of combustion. The standard molar enthalpy of formation of the compound is calculated to be △fHo（1-C12H25NH3.Br, s）=-（1317.86~3.67） kJ.mo1-1 from the standard molar enthalpy of combustion of the title compound and other auxiliary thermodynamic quantities through a thermochemical cycle.

Low-temperature heat capacities and standard molar enthalpy of formation of 4-(2-aminoethyl)-phenol (C_8H_(11)NO)

This paper reports that low-temperature heat capacities of 4-（2-aminoethyl）-phenol （C8H11NO） are 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 the temperature was fitted by the least square method. Based on the fitted polynomial, the smoothed heat capacities and thermodynamic functions of the compound relative to the standard reference temperature 298.15K were calculated and tabulated at the interval of 5K. The energy equivalent, εcalor, of the oxygen-bomb combustion calorimeter has been determined from 0.68g of NIST 39i benzoic acid to be εcalor=（14674.69±17.49）J·K^-1. 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=-（32374.25±12.93）J·g^-1. The standard molar enthalpy of combustion for the compound was calculated to be ΔcHm = -（4445.47 ± 1.77） kJ·mol^-1 according to the definition of enthalpy of combustion and other thermodynamic principles. Finally, the standard molar enthalpy of formation of the compound was derived to be ΔfHm（C8H11NO, s）=-（274.68 ±2.06） kJ·mol^-1, in accordance with Hess law.

Standard Molar Enthalpy of Formation of Morin Studied by Rotating-Bomb Combustion Calorimetry

Flavonols are plant nature. Morin and other related pigments that are ubiquitous in plant flavonols have come into recent prominence because of their usefulness as anticancer, antitumor, anti-AIDS, and other important therapeutic activities of significant potency and low systemic toxicity. The heat of combustion of morin （molecular formula, C15H10O7·H2O） in oxygen was measured by a rotating-bomb type combustion calorimeter, the standard molar enthalpy of combustion of morin at T = 298.15 K was determined to be △cH^ m （C15H10O7·H2O, s） = - （5 937.99±2.99） kJ·mol^-1. The derived standard molar enthalpy of the formation of morin in solid powder state at T = 298.15 K, △fH^ m（C15H10O7·H2O, s）, was -（1 682.12 ± 3.58） kJ·mol^1, which provide an accurate data of the stability of morin to the pharmacy and pharmacology.

Low-temperature heat capacities and standard molar enthalpy of formation of N-methylnorephedrine C11H17NO（s）

This paper reports that low-temperature heat capacities of N-methylnorephedrine C11H17NO（s） have been measured by a precision automated adiabatic calorimeter over the temperature range from T=78K to T=400K. A solid to liquid phase transition of the compound was found in the heat capacity curve in the temperature range of T=342-364 K. The peak temperature, molar enthalpy and entropy of fusion of the substance were determined. The experimental values of the molar heat capacities in the temperature regions of T=78-342 K and T=364-400 K were fitted to two poly- nomial equations of heat capacities with the reduced temperatures by least squares method. The smoothed molar heat capacities and thermodynamic functions of N-methylnorephedrine C11H17NO（s） relative to the standard refer- ence temperature 298.15 K were calculated based on the fitted polynomials and tabulated with an interval of 5 K. The constant-volume energy of combustion of the compound at T=298.15 K was measured by means of an isoperibol precision oxygen-bomb combustion calorimeter. The standard molar enthalpy of combustion of the sample was calculated. The standard molar enthalpy of formation of the compound was determined from the combustion enthalpy and other auxiliary thermodynamic data through a Hess thermochemical cycle.

Synthesis and Determination of Standard Molar Enthalpies of Formation for Complexes of Rare Earth Isothiocyanates with Glycine

Four solid complexes of rare earth isothiocyanates with glycine were synthesized. They were characterized by chemical analysis, elemental analysis, Infrared spectra, X-ray powder diffraction and TO-DSC analysis. Their chemical formulae were proved to be RE(NCS)2.Gly .H2O, where RE is La, Ce, Pr or Nd. The integral heats of solution of RE(NCS)3.3Gly. H2O in water, of RE(NCS)2. 7H2O in aqueous glycine solution and of glycine in water have been measured calorimetricaliy at 298. 15K. By means of a thermochemical cycle suggested in this paper, the standard molar enthalpies of formation for RE(NCS)2. 3Gly.H2O(c) were obtained and their lattice energies were calculated.

Low-temperature Heat Capacity and Standard Molar Enthalpy of Formation of Potassium L-Threonate Hydrate K（C4H7O5）·H2O

The solid potassium L-threonate hydrate, K（C4H7O5）·H2O, was synthesized by the reaction of L-threonic acid with aqueous potassium hydrogen carbonate and characterized by means of chemical and elemental analyses, IR and TG-DTG. Low-temperature heat capacity of K（C4H7O5）·H2O has been precisely measured with a small sample precise automated adiabatic calorimeter over the temperature range from 78 to 395 K. An obvious process of the dehydration occurred in the temperature region of 364-382 K. The peak temperature of the dehydration of the compound has been observed to be （380.524±0.093） K by means of the heat capacity measurements. The molar enthalpy, △dHm, and molar entropy, △dSm, of the dehydration of K（C4H7O5）·H2O were calculated to be （19.655 ± 0.012） kJ/mol and （51.618 ± 0.051） J/（K·mol） by the analysis of the heat-capacity curve. The experimental molar heat capacities of the solid from 78 to 362 K and from 382 to 395 K have been respectively fitted to two polynomial equations of heat capacities against the reduced temperatures by least square method. The constant-volume energy of combustion of the compound, △cUm, has been determined to be （- 1749.71 ±0.91） kJ·mol^-1 by an RBC-Ⅱ precision rotary-bomb combustion calorimeter at 298.15 K. The standard molar enthalpy of formation of the compound, △fHm , has been calculated to be （- 1292.56± 1.06） kJ·mol^-1 from the combination of the standard molar enthalpy of combustion of the compound with other auxiliary thermodynamic quantities.

Crystal Structure, Thermal Decomposition Behavior and the Standard Molar Enthalpy of Formation of a Novel 3D Hydrogen- Bonded Supramolecular [Co（HnicO）2·（H2O）2]

Hydrothermal synthesis and X-ray characterized 3D supramolecular networks were constructed by [Co（HnicO）2·（H2O）2] （HnicOH=2-hydroxynicofinic acid） （1） as building block via abundant dimeric homomeric （N--H…O） and unusually cyclic tetrameric heteromeric （O-H…O） hydrogen-bonds. It is noted that there exist unusually linear metal-water chains comprised of tetrameric units linked by vertexes sharing cobalt centers through hydrogen-bonding. TG-DTG curves illustrated that thermal decomposition was completed by two steps, one is the loss of two terminal water molecules in the range of 156--234℃, and the other is the pyrolysis of HnicO ligand in the range of 234--730 ℃. The standard molar enthalpy of formation of the complex was determined to be （-1845.43± 2.77） kJ·mol^-1 by a rotary-bomb combustion calorimeter.

Low-Temperature Heat Capacities and Standard Molar Enthalpy of Formation of Gramine （C11H14N2）

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 △cU=-（35336.7±13.9） j·g^-1. The standard molar enthalpy of combustion of the compound was determined to be △cHm=-（6163.2±2.4） kJ·mol^-1, according to the definition of combustion enthalpy. Finally, the standard molar enthalpy of formation of the compound was calculated to be △cHm=-（166.2±2.8） kJ·mol-1 in accordance with Hess law.

A Thermochemical Study of the Reaction of Lanthanum Nitrate with Alanine

The standard molar reaction enthalpy of the solid-solid coordination reaction La(NO3)3. 6H2O (s) +4Ala(s) (Ala is Alanine)=La(NO3)3·(Ala)4·H2O(s) + 5H2O(1) was studied by using classical solution calorimetry. The molar dissolution enthalpies of the reactants and the product of the solid-solid coordination reaction in 2 mol/L HCl were measured by using an isoperibol calorimeter. From the results and other auxiliary quantities, the standard molar formation enthalpy of [La (NO3)3·(Ala)4·H2O, s, 298. 15 K] has been determined to be △fHm[La(NO3)3·(Ala)4·H2O, s, 298. 15 K]=-3 864. 248 kJ/mol.

Thermochemical Study on Coordination Complex of Samarium with Salicylic Acid and 8-Hydroxyquinoline

The coordination complex Sm（C7H5O2）2·（C9H6NO）, synthesized from the reaction of samarium chloride sixhydrate with salicylic acid and 8-hydroxyquinoline, was characterized with IR, elemental analysis, molar conductance, and thermogravimatric analysis. The standard molar enthalpies of solution of [ SmCl3·6H2O （s） ], [ 2C7H6O3 （s） ], [ C9H7NO （ s ） ] and [ Sm （C7H5O3） 2·（ C9H6NO ） （ s ） ] in the calorimetric solvent were determined with the solution-reaction isoperibol calorimeter at 298.15 K to be △sHm^- [ SmCl3·6H2O （s）, 298.15 K ] = - 103.98 ± 0.04 kJ·mol^-1, △sHm^- [2 C7H6O3 （s）, 298.15 K] = 16.35±0.14 kJ·mol^-1,△sHm^-[C9H7NO （s）, 298.15 K] = -6.11±0.08 kJ·mol^-1 and △sHm^-[Sm（C7H5O3）2·（C9H6NO） （s）, 298.15 K] = - 130.08 ± 0.04 kJ·mol^-1, respectively. The enthalpy was determined to be △rHm^- = 89.59 ±0.18 kJ·mol^-1 for the reaction SmCl3·6H2O（s） ＋ 2C7H6O3（s） ＋ C9H7NO（s） = Sm （C7H5O3） 2·（C9H6NO） （ s ） ＋ 3HCl （g） ＋ 6H2O （ l ）. According to the above results and the data given in literature and through Hess＇ law, the standard molar enthalpy of formation of Sin（ C7H5O3 ）2·（C9H7NO）（s） was estimated to be △rHm^- [ Sm （C7H5O3）2·（C9H6NO） （s）, 298.15 K] = - 2055.9 ± 3.03 kJ·mol^-1.

Thermochemical Study on Ternary Solid Complex of La(Gly)_2(Ala)_3Cl_3·2H_2O(s)

The complex of lanthanum chloride with Glycine and Alanine,La（Gly）2（Ala）3Cl3·2H2O,was synthesized and characterized by IR,elementary analysis,thermogravimetric analysis,and chemical analysis.The dissolution enthalpies of LaCl3 ·7H2O（s）,2Gly（s）＋ 3Ala（s）and La（Gly）2（Ala）3Cl3 ·2H2O（s）were determined in 2 mol·L-1 HCl by a solution-reaction isoperibol calorimeter.By designing a thermochemical cycle in terms of Hess＇ Law and through calculation,the reaction enthalpy of lanthanum chloride seven-hydrate with Glycine and Alanine was obtained：ΔrHθm（298.15 K）=（29.652±0.504）kJ·mol-1,and the standard enthalpy of formation of La（Gly）2（Ala）3Cl3·2H2O（s）ΔfHθm [La（Gly）2（Ala）3Cl3·2H2O,s,298.15 K]=-4467.6±8.3 kJ·mol-1.

Thermochemical Study of Lanthanum Complex Crystal with β-Alanine

Lanthanum complex crystal with β alanine (1∶3) was synthesized. Through the DTA,TG,chemistry analysis and comparison with literature, it shows that its form is {[La 2(β ala) 6· (H 2O) 4](ClO 4) 6·H 2O} n , and its purity is 98.86%. The dissolution enthalpy of the reactants and products in 2 mol·L -1 HCl solution (298.15K) was measured by using the isoperibol reaction calorimetry. Δ rH m was calculated by a designed thermochemical cycle of the coordination reaction. From the results and other auxiliary quantities, the standard molar enthalpy of formation of [La 2(β ala) 6·(H 2O) 4](ClO 4) 6·H 2O is obtained to be Δ fH m°{[La 2(β ala) 6·(H 2O) 4](ClO 4) 6·H 2O} = - 7062.911 kJ·mol -1 .

Synthesis,Characterization and Calorimetry of Ni(C_4H_8N_2O_3)_2Cl_2

A coordination complex was synthesized from NiCl2 and dipeptide glycylglycine（GG）. It was characterized by element analysis, NMR and TG methods, and then was determined to be Ni（C4HsN2O3）2Cl2. Using an isoperibolic reaction calorimeter, the standard molar enthalpy of formation of Ni（GG）2Cl2（solid） has been determined to be -（1 674.66±2.02） kJ · mol^-1 at 298.15 K.

Thermochemistry of the Ternary Complex Nd(Et_2dtc)_3(phen)

The ternary solid complex has been synthesized with sodium diethyldithiocarbamate (NaEt2dtc?3H2O), 1,10-phenanthroline (o-phen?H2O) and hydrated neodymium chloride in absolute ethanol. The title complex was identified as the general formula of Nd(Et2dtc)3(phen) by chemical and elemental analyses. IR spectrum of the complex showed that the Nd3+ coordinated with six sulfur atoms of three NaEt2dtc and two nitrogen atoms of o-phen. It was assumed that the coordination number of Nd3+ is eight.The enthalpy change of liquid-phase reaction of formation, ?rHm (l), was determined as (-12.274±0.050) kJ?mol-1 at 298.15 K by a microcalorimeter, the Θ enthalpy change of the solid-phase reaction of formation, ?rHm (s), was calculated as (149.069±0.314) kJ?mol-1 Θ on the basis of a thermochemical cycle. The thermodynamics of reaction of formation was studied by changing the temperature of liquid-phase reaction. The constant-volume combustion energy of the complex, ?cU , was deter- mined as (-18674.22±8.33) kJ?mol-1 by a precise rotating-bomb calorimeter at 298.15 K. Its standard enthalpy of combustion, ?cHm , and standard enthalpy of formation, ?fHm , were calculated as (-18693.43±8.33) kJ?mol-1 Θ Θ and (-47.03±9.17) kJ?mol-1, respectively.

Crystal Structure and Thermochemical Properties of 2-Pyrazine Carboxylate Lithium Monohydrate [Li（pyza）（H2O）]n（S）（pyza=2-Pyrazine Carboxylate）

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

Synthesis,Characterization and Thermochemistry of 2MgO·B_2O_3·1.5H_2O

A new magnesium borate 2MgO·B_ 2 O_ 3 ·1.5H_ 2 O has been synthesized by the method of phase transformation of double salt under hydrothermal condition and characterized by XRD,IR,Raman spectra and TG. The enthalpy of solution of 2MgO· B_ 2 O_ 3 ·1.5H_ 2 O in 2.9842 mol·L -1 HCl was determined. From a combination of this result with measured enthalpies of solution of H_ 3 BO_ 3 in 2.9842 mol·L -1 HCl(aq.) and of MgO in (HCl+H_ 3 BO_ 3 ) solution,together with the standard molar enthalpies of formation of MgO(s),H_ 3 BO_ 3 (s),and H_ 2 O(l),the standard molar enthalpy of formation of -(3019.76±1.79) kJ· mol -1 of 2MgO·B_ 2 O_ 3 ·1.5H_ 2 O was obtained.

Thermochemistry on the Complex of Erbium Perchlorate with L-α-Glutamic Acid [Er2（L-Glu）2（H2O）6]（ClO4）4·6H2O（s）

A coordination compound of erbium perchlorate with L-α-glutamic acid, [Er2（Glu）2（H2O）6]（ClO4）4·6H2O（s）, was synthesized. By chemical analysis, elemental analysis, FTIR, TG/DTG, and comparison with relevant literatures, its chemical composition and structure were established. The mechanism of thermal decomposition of the complex was deduced on the basis of the TG/DTG analysis. Low-temperature heat capacities were measured by a precision automated adiabatic calorimeter from 78 to 318 K. An endothermic peak in the heat capacity curve was observed over the temperature region of 290-318 K, which was ascribed to a solid-to-solid phase transition. The temperature Ttrans, the enthalpy △transHm and the entropy △transSm of the phase transition for the compound were determined to be： （308.73±0.45） K, （10.49±0.05） kJ·mol^-1 and （33.9±0.2） J·K^-1·mol^-1. Polynomial equation of heat capacities as a function of the temperature in the region of 78-290 K was fitted by the least square method. Standard molar enthalpies of dissolution of the mixture [2ErCl3·6H2O（s）＋2L-Glu（s）＋6NaClO4·H2O（s）] and the mixture {[Er2（Glu）2（H2O）6]（ClO4）4·6H2O（s）＋6NaCl（s）} in 100 mL of 2 mol·dm^-3 HClO4 as calorimetric solvent, and {2HClO4（1）} in the solution A＇ at T=298.15 K were measured to be, △dHm,1=（31.552±0.026） kJ·mol^-1, △dHm,2 = （41.302±0.034） kJ·mol^-1, and △dHm,3 = （ 14.986 ± 0.064） kJ·mol^-1, respectively. In accordance with Hess law, the standard molar enthalpy of formation of the complex was determined as △fHm-=-（7551.0±2.4） kJ·mol^-1 by using an isoperibol solution-reaction calorimeter and designing a thermochemical cycle.