Balanced solubility product and enthalpies of formation of Nb compounds in 0.09 % oriented silicon steel

Balance solubility products and enthalpy of for- mation for NbC0.75, NbC0.85, NbC0.88, NbC and NbN in oriented silicon steels were calculated and compared quali- tatively. Meanwhile, the mixing enthalpies of these five Nb compounds were calculated based on Miedema Model. The results show that the solubility products of Nb compounds in ferrite and austenite meet the following relationship, NbC0.75 〉 NbC0.85 〉 NbC0.88 〉 NbC 〉 NbN and NbN has the minimum enthalpy of formation. It indicates that NbN easily precipitate out, but it is more difficult for NbC0.75.

Standard energies of combustion and standard enthalpies of formation for the complexes RE (Et_2dtc)_3(phen) (RE = Ho,Er,Tm,Yb,Lu)

The treatment of RECl3.xH2O （RE = Ho, Er, Tm, Yb, Lu; x = 3-4） with sodium diethyldithiocarbamate （NaEtEdtc-3H2O） and 1,10-phenanthroline hydrate （o-phen.H2O） in absolute ethanol yielded five ternary solid complexes RE（EtEdtC）a（phen）. IR spectra of the complexes showed that RE^3＋ coordinated to two sulfur atoms in NaEt2dtc and two nitrogen atoms in o-phen. The constant-volume energies of combustion of the complexes have been determined by a precise rotating-bomb calorimeter at 298.15 K. The standard enthalpies of combustion and standard enthalpies of formation were calculated.

Determination of Standard Molar Enthalpies of Formation for "White Powdery Tungstic Acid" and for Dodecatungstophosphoric Acid by Solution Calorimetry

'White powdery tungstic acid' has been used for preparing various types of tungsten-containing compounds due to its high reactivity. The present paper covers the standard molar enthalpies of formation, △H0/f of three tungsten- containing acids. The values found for 'white powdery tungstic acid' WO3·1. 68H2O, 'yellow tungstic acid' WO3·1. 20H2O and dodecatungstophosphoric acid H3(PW12O40)·25H2O at 298. 15 K were-(1312±1), - (1192±1) and -(18150±13) kJ mol-1, respectively.

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.

Standard Enthalpies of Formation of Solid Complexes of Lanthanide Nitrates with Alanine

The combustion energies of fourteen solid complexes of lanthanide nitrate with alanine were determined. The standard enthalpies of combustion, Δ c,coor(s) H °, and standard enthalpies of formation, Δ f,coor(s) H °, were calculated for these complexes. The relationship of Δ c,coor(s) H ° and Δ f,coor(s) H ° with the atomic numbers of the elements in the lanthanide series were examined. The results show that a certain amount of covalence is present in the chemical bond between the lanthanide cations and alanine.

Enthalpies of Formation of Noble Metal Binary Alloys Bearing Rh or Ir

The modified embedded atom method proposed by authors has been applied to calculating the enthalpies of formation of random alloys and the ordered intermetallic compounds for noble metal binary systems bearing Rh or Ir. The present results are in good agreement with those of Miedema theory, available experiments and the first-principles quantum mechanics calculations. The present results indicate that Cu-Rh, Cu-lr, Ag-Rh, Ag-lr, Au-Rh, Au-lr, Pd-Rh and Pd-lr systems are repulsive, however, IMi-Rh, Ni-lr, Pt-lr, Pt-Rh and Rh-lr systems form solid solutions and Ni-Rh, Ni-lr and Pt-Rh show ordering tendency.

Determination of Standard Molar Enthalpies of Formation of Complexes of Rare Earth Bromides with Glycine

The integral heat of solution of REBr 3·3Gly·3H 2O(RE=La, Pr, Nd, Sm, Eu, Gd, Tb, Dy and Y; Gly is glycine) in water, REBr 3· n H 2O(RE=La, Ce and Pr, n =7; RE=Nd, Sm, Eu, Gd, Tb, Dy and Y, n =6) in aqueous glycine solution and glycine in water have been measured calorimetrically at 298 15±0 15 K. By means of a thermochemical cycle suggested in this paper, the standard molar enthalpies of formation of REBr 3·3Gly·3H 2O have been obtained and their lattice energies have been calculated.

Standard Enthalpies of Formation for Solid Complexes of Chromium Chloride with L-α-Amino Acids

The solid complexes of Cr(AA) 2Cl 3·nH 2O of CrCl 3 with L-α-amino acids (AA=Val, Leu, Thr, Met, Arg, Phe, Try and His) have been prepared in 95% EtOH medium, and characterized structurally by elemental analysis, chemical analysis, IR spectra and TG-DTG. The constant-volume combustion energies of the complexes have been determined by RBC-II type rotating-bomb calorimeter. The standard enthalpies of formation of the complexes have been calculated as well, which are ( -2543.16± 3.71) (Val), ( -2561.32± 4.06) (Leu), ( -2284.02± 2.95) (Thr), ( -1418.77± 4.60) (Met), ( -3218.91± 4.67) (Arg), ( -2643.90± 5.02) (Phe), ( -1707.18± 3.23) (Try) and ( -2838.05±3.45) (His) kJ/ mol, respectively.

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.

Enthalpy of formation of quasicrystalline phase and ternary solid solutions in the Al-Fe-Cu system

Standard enthalpies of formation of quasicrystalline phase and the ternary solid solutions in the Al-Fe-Cu system and the intermetaUic compound FeAI were determined by the means of solution calorimetry. The quasicrystalline phase was prepared using two different methods. The first method （I） consisted of ball milling the mixture of powders of pure aluminum copper and iron in a planetary mill with subsequent compacting by hot pressing and annealing. The second method （Ⅱ） consisted of arc melting of the components in argon atmosphere followed by annealing. The latter method was used for preparing the compound FeAl and the solid solutions. The phases were identified using the XRD method. The enthalpy of the formation was determined for the quasicrystalline phase of the composition Al62Cu25.5Fe12.5 and the temary BCC solid solutions Al35Cu14Fe51, Al40Cu17Fe43, and Al50.4Cu19.6Fe30. The measured enthalpy of formation of the intermetallic compound FeAl is in good agreement with the earlier published data. The enthalpies of formation of the quasicrystalline phases prepared using two different methods are close to each other, namely, -22.7±3.4 （method I） and -21.3±2.1 （method Ⅱ） kJ/mol.

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).

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.

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.

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.

Preparation and Standard Formation Enthalpy of 2-Amino-4,6-dimethylpyrimidine and Its Related Complexes of Copper

The complexes of hydrous copper chloride and copper nitrate with 2-amino-4,6-dimethylpyrimidine(ADMP) were prepared via reflux in alcohol. The compositions of the complexes were identified as Cu(ADMP) 2Cl 2·2H 2O(b) and Cu(ADMP)(NO 3) 2·H 2O(c) by chemical and elemental analyses. The complexes were characterized by IR, XPS, 1H NMR and TG-DTG techniques. The constant-volume combustion energies of ADMP and the complexes, Δ c E , were determined by a precise rotating-bomb calorimeter at 298 15 K. They were (-3664 53±1 18), (-4978 47±2 72) and (-1696 70±1 36) kJ/mol, respectively. Their standard enthalpies of combustion, Δ c H 0 m, and standard enthalpies of formation, Δ f H 0 m, were calculated to be (-3666 39±1 18), (-4977 23±2 72), (-1691 12±1 36) kJ/mol and (19 09±1 43), (-2041 80±3 29), (-2397 24±1 65) kJ/mol, respectively.

Standard Enthalpy of Formation of Monoclinic Ammonium Paratungstate

The enthalpy of reaction for the decomposition of monoclinic ammonium paratungstate,(NH_4 )_10 H_2, W_12 O_424H_2 O(s), was measured using a HT-1000 calorimeter. From the experimentalresults, the standard enthalpy of formation of ammonium paratlingstate at 298.15 K is obtained.

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.

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 Properties of the Complexes RE(HSal)_3·2H_2O (RE=La,Ce,Pr,Nd,Sm)

Five solid rare earth salicylate complexes were synthesized by low hydrated lathanide chloride and salicylic acid. The complexes in this experiment were identified as the general formula RE（HSal）3·2H2O（RE = La, Ce, Pr, Nd, Sm） by elemental analysis and EDTA volumetric analysis. IR spectra of the complexes show that carboxyl of salicylic acid coordinates to RE^3＋ ions. Electrochemical behaviors of the complexes on the glass-carbon electrode were researched with cyclic voltammetry （CV）. It is indicated that the electrochemical process of the complexes is a one-electron redox process and the electrochemical reversibility of complexes is less than that of the lanthanide chlorides. The constant-volume combustion energies of complexes,△c U, were determined with a precise rotating-bomb calorimeter at 298.15 K. Their standard molar enthalpies of combustion, △cH^θm, and standard molar enthalpies of formation, △fH^θm, were calculated.