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Molar Enthalpies (molar + enthalpy)

Distribution by Scientific Domains
Chemistry87%

Kinds of Molar Enthalpies

  • standard molar enthalpy
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    Selected Abstracts

    Determination of Standard Molar Enthalpies of Formation for the Two Barium Borates BaB2O4×xH2O (x = 4, 0) by Microcalorimetry.

    CHEMINFORM, Issue 22 2007
    Zhi-Hong Liu
    Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source]

    Crystal Structure, Lattice Energy, and Standard Molar Enthalpy of Formation of the Complex (C11H18NO)2CuCl4 (s)

    CHINESE JOURNAL OF CHEMISTRY, Issue 7 2010
    Wenyan Dan
    Abstract The complex (C11H18NO)2CuCl4 (s), which may be a potential effective drug, was synthesized. X-ray crystallography, elemental analysis, and chemical analysis were used to characterize the structure and composition of the complex. Lattice energy and ionic radius of the anion of the complex were derived from the crystal data of the title compound. In addition, a reasonable thermochemical cycle was designed, and standard molar enthalpies of dissolution for reactants and products of the synthesis reaction of the complex were measured by an isoperibol solution-reaction calorimeter. The enthalpy change of the reaction was calculated to be ,rH,m=(2.69±0.02) kJ·mol,1 from the data of the above standard molar enthalpies of dissolution. Finally, the standard molar enthalpy of formation of the title compound was determined to be ,rH,m[(C11 H18NO)2CuCl4, s]= , (1822.96±6.80) kJ·mol,1 in accordance with Hess law. [source]

    Thermodynamic and Structural Properties of Sodium Lithium Niobate Solid Solutions

    JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 2 2002
    Irina Pozdnyakova
    Thermodynamics of the Na1,xLixNbO3 system is investigated by high-temperature drop-solution calorimetry in molten 3Na2O,4MoO3 solvent at 973 K. Standard molar enthalpies of formation are derived. The estimated heats of transition between hypothetical and stable structures, lithium niobate and perovskite for NaNbO3 and vice versa for LiNbO3 are ,6 kJ/mol and ,10 kJ/mol, respectively. X-ray diffraction studies at room temperature showed for 0 ,x, 0.14 there are three phases based on different ordering of the perovskite type lattice: orthorhombic with a quadrupled reduced perovskite cell at 0 ,x, 0.02, orthorhombic with a doubled reduced perovskite cell at 0.015 ,x, 0.14, and rhombohedral at 0.08 ,x, 0.13. There are two two-phase (morphotropic) regions with coexistence of the two orthorhombic phases at 0.015 ,x, 0.02 and with the second orthorhombic phase coexisting with the rhombohedral phase at 0.08 ,x, 0.13. A reproducible anomaly in specific heat at ,600 K, not reported previously, has been observed in pure NaNbO3. Heat-capacity measurements confirm a phase transition at 553 K for 0.07 ,x, 0.09. With increasing lithium concentration, a gradual disappearance of high-temperature phase transitions associated with tilting of oxygen octahedra has been observed. [source]

    Energetic N,N,N,,N, -Tetraaminopiperazinium Salts

    CHEMSUSCHEM CHEMISTRY AND SUSTAINABILITY, ENERGY & MATERIALS, Issue 3 2008
    Haixiang Gao Prof.
    Abstract The formation of tetraaminopiperazinium salts using water as solvent provides a green, straightforward approach to highly energetic salts that exhibit good thermal stabilities and moderate densities. The N,N,N,,N, -tetraaminopiperazinium cation was selected for this study because of its high nitrogen,nitrogen bond content and its high positive heat of formation. Theoretical and empirical calculations on energetic salts based on this nitrogen-rich cation reveal them to have high positive molar enthalpies of formation, as high as 1034.0,kJ,mol,1, supporting the application of these new salts as potential energetic materials. [source]

    Crystal Structure, Lattice Energy, and Standard Molar Enthalpy of Formation of the Complex (C11H18NO)2CuCl4 (s)

    CHINESE JOURNAL OF CHEMISTRY, Issue 7 2010
    Wenyan Dan
    Abstract The complex (C11H18NO)2CuCl4 (s), which may be a potential effective drug, was synthesized. X-ray crystallography, elemental analysis, and chemical analysis were used to characterize the structure and composition of the complex. Lattice energy and ionic radius of the anion of the complex were derived from the crystal data of the title compound. In addition, a reasonable thermochemical cycle was designed, and standard molar enthalpies of dissolution for reactants and products of the synthesis reaction of the complex were measured by an isoperibol solution-reaction calorimeter. The enthalpy change of the reaction was calculated to be ,rH,m=(2.69±0.02) kJ·mol,1 from the data of the above standard molar enthalpies of dissolution. Finally, the standard molar enthalpy of formation of the title compound was determined to be ,rH,m[(C11 H18NO)2CuCl4, s]= , (1822.96±6.80) kJ·mol,1 in accordance with Hess law. [source]

    Thermochemical Properties and Decomposition Kinetics of Ammonium Magnesium Phosphate Monohydrate

    CHINESE JOURNAL OF CHEMISTRY, Issue 1 2007
    Jian Wu
    Abstract Ammonium magnesium phosphate monohydrate NH4MgPO4·H2O was prepared via solid state reaction at room temperature and characterized by XRD, FT-IR and SEM. Thermochemical study was performed by an isoperibol solution calorimeter, non-isothermal measurement was used in a multivariate non-linear regression analysis to determine the kinetic reaction parameters. The results show that the molar enthalpy of reaction above is (28.795±0.182) kJ/mol (298.15 K), and the standard molar enthalpy of formation of the title complex is (,2185.43±13.80) kJ/mol (298.15 K). Kinetics analysis shows that the second decomposition of NH4MgPO4·H2O acts as a double-step reaction:an nth-order reaction (Fn) with n=4.28, E1=147.35 kJ/mol, A1=3.63×1013 s,1 is followed by a second-order reaction (F2) with E2=212.71 kJ/mol, A2=1.82×1018 s,1. [source]