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Abstract  

Sr2CeO4 has been prepared by sol-combustion and co-precipitate routes and the resulting products have been characterized by XRD analysis. The molar enthalpies of solution of Sr2CeO4, Sr(NO3)2(s) and Ce(NO3)36H2O(s) in 0.150 dm3 of (4.41 mol dm3 H2O2+4.23 mol dm-3 of HNO3) solvent as well as the molar enthalpies of solution of Sr2CeO4(s), SrCl2(s) and CeCl3(s) in 0.150 dm3of (1.47 mol dm-3 H2O2+3.05 mol dm-3 of HClO4) solvent have been measured using an isoperibol type calorimeter. From these results and other auxiliary data, the standard molar enthalpy of formation of Sr2CeO4 has been derived to be -2277.33.1 kJ mol-1 at 298.15 K. This is the first reported thermodynamic data on this compound.

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Abstract  

The empirical regularities of the SEF for relative inorganic substances in binary and quasibinary systems (energetic and dimensional rules of linear approximation - ELAR and DLAR) are described.

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Abstract  

The heats of dissolution of the crystalline L-phenylalanine and D,L-phenylalanine in water and potassium hydroxide solutions at 298.15 K which were determined by direct calorimetric method are reported. These heats made available calculations the standard enthalpies of the phenylalanine isomers and the products of their dissociation in aqueous solutions.

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Abstract  

The standard enthalpies of tellurites of Y, La, Ce and Pr were determined by differential scanning calorimetric (DSC) method. The completeness of the chemical reactions between the metal oxides and tellurous oxide were checked by DSC and X-ray powder diffraction methods. The calculated standard enthalpies are presented.

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Abstract  

The constant-volume combustion energies of the lead salts of 2-hydroxy-3,5-dinitropyridine (2HDNPPb) and 4-hydroxy-3,5-dinitropyridine (4HDNPPb), ΔU c (2HDNPPb(s) and 4HDNPP(s)), were determined as –4441.922.43 and –4515.741.92 kJ mol–1 , respectively, at 298.15 K. Their standard enthalpies of combustion, Δc m H θ(2HDNPPb(s) and 4HDNPPb(s), 298.15 K), and standard enthalpies of formation, Δr m H θ(2HDNPPb(s) and 4HDNPPb(s), 298.15 K) were as –4425.812.43, –4499.631.92 kJ mol–1 and –870.432.76, –796.652.32 kJ mol–1 , respectively. As two combustion catalysts, 2HDNPPb and 4HDNPPb can enhance the burning rate and reduce the pressure exponent of RDX–CMDB propellant.

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Abstract  

Solid complexes of M(His)2Cl2 nH2O (M=Mn, Co, Ni, Cu) of MnCl26H2O, CoCl26H2O, NiCl26H2O, CuCl22H2O and L-α-histidine (His) have been prepared in 95% ethanol solution and characterized by elemental analyses, chemical analyses, IR and TG-DTG. The constant-volume combustion energies of the complexes have been determined by a rotating-bomb calorimeter. And the standard enthalpies of formation of the complexes have been calculated as well.

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Abstract  

The two complexes, [Ln(Ala)2(Im)(H2O)](ClO4)3 (Ln=Pr, Gd), were synthesized and characterized. Using a solution-reaction isoperibol calorimeter, standard enthalpies of reaction of two reactions: LnCl3⋅6H2O(s)+2Ala(s)+Im(s)+3NaClO4(s)=[Ln(Ala)2(Im)(H2O)](ClO4)3(s)+3NaCl(s)+5H2O(l) (Ln=Pr, Gd), at T=298.15 K, were determined to be (39.260.10) and (5.330.12) kJ mol–1 , respectively. Standard enthalpies of formation of the two complexes at T=298.15 K, Δf H Θ m {[Ln(Ala)2(Im)(H2O)](ClO4)3(s)} (Ln=Pr, Gd), were calculated as –(2424.23.3) and –(2443.43.3) kJ mol–1 , respectively.

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Summary A ternary solid complex Gd(Et2dtc)3(phen) has been obtained from reactions of sodium diethyldithiocarbamate (NaEt2dtc), 1,10-phenanthroline (phen) and hydrated gadolinium chloride in absolute ethanol. The title complex was described by chemical and elemental analyses, TG-DTG and IR spectrum. The enthalpy change of liquid-phase reaction of formation of the complex, Δr H Θ m(l), was determined as (-11.628±0.0204) kJ mol-1 at 298.15 K by a RD-496 III heat conduction microcalorimeter. The enthalpy change of the solid-phase reaction of formation of the complex, Δr H Θ m(s), was calculated as (145.306±0.519) kJ mol-1 on the basis of a designed thermochemical cycle. The thermodynamics of reaction of formation of the complex was investigated by changing the temperature of liquid-phase reaction. Fundamental parameters, the apparent reaction rate constant (k), the apparent activation energy (E), the pre-exponential constant (A), the reaction order (n), the activation enthalpy (Δr H Θ ), the activation entropy (Δr S Θ ), the activation free energy (Δr G Θ ) and the enthalpy (Δr H Θ ), were obtained by combination of the thermodynamic and kinetic equations for the reaction with the data of thermokinetic experiments. The constant-volume combustion energy of the complex, Δc U, was determined as (-18673.71±8.15) kJ mol-1 by a RBC-II rotating-bomb calorimeter at 298.15 K. Its standard enthalpy of combustion, Δc H Θ m, and standard enthalpy of formation, Δf H Θ m, were calculated to be (-18692.92±8.15) kJ mol-1 and (-51.28±9.17) kJ mol-1, respectively.

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Abstract  

The solid complexes of Cr(NO3)3 with L-α-amino acids (AA=Val, Leu, Thr, Arg, Phe and Try) have been prepared in 95% alcoholic, the compositions of which were identified as the general formula Cr(AA)2(NO3)32H2O by elemental and chemical analyses. The bonding characteristics of the title complexes were characterized by IR, indicating that nitrogen and oxygen atoms in the ligands coordinated to Cr3+ in a bidentate fashion. With the aid of TG-DTG and IR techniques, the complexes were subjected to thermal decomposition in an atmosphere of oxygen, presuming that the decompositions of the complexes consist of two steps and the complexes were decomposed into chromium hemitrioxide after undergoing dehydration and skeleton splitting of the complexes. The constant volume energies of combustion of the complexes were determined by a RBC-P type rotating-bomb calorimeter. According to Hess's law, the standard enthalpies of formation of the complexes were calculated as (-1831.404.40), (-2542.036.13), (-1723.813.99), (-2224.313.02), (-2911.616.53) and (-659.327.42) kJ mol-1, respectively.

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Abstract  

[Cd(NTO)4Cd(H2O)6]4H2O was prepared by mixing the aqueous solution of 3-nitro-1,2,4-triazol-5-one and cadmium carbonate in excess. The single crystal structure was determined by a four-circle X-ray diffractometer. The crystal is monoclinic, space group C2/c with crystal parameters of a=2.1229(3) nm, b=0.6261(8) nm, c=2.1165(3) nm, β=90.602(7), V=2.977(6) nm3, Z=4, Dc=2.055 gcm−3, μ=15.45 cm−1, F(000)=1824, λ(MoKα)=0.071073 nm. The final R is 0.0282. Based on the results of thermal analysis, the thermal decomposition mechanism of [Cd(NTO)4Cd(H2O)6]4H2O was derived. From measurements of the enthalpy of solution of [Cd(NTO)4Cd(H2O)6]4H2O in water at 298.15 K, the standard enthalpy of formation, lattice energy, lattice enthalpy and standard enthalpy of dehydration have been determined as -(1747.84.8), -2394, -2414 and 313.6 kJ mol−1 respectively.

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