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1.
M. I. Ivanov V. V. Berezutskii V. G. Kudin M. A. Shevchenko V. S. Sudavtsova 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2011,85(12):2068-2073
Partial and integral enthalpies of mixing of melts of the Eu-Pd system were determined by calorimetry at 1300 K in the concentration
interval of 0 < x
Pd < 0.37. It was established that the first partial enthalpy of mixing of Pd was −158 ± 2 kJ/mol. The thermodynamic properties
of Eu-Pd melts were simulated according to the theory of ideal associated solutions over a wide interval of concentrations
and temperatures. It was shown that the activities of components display strong negative deviations from Raoult’s law, and
the minima of the integral Gibbs energies and enthalpies of mixing were found at x
Pd = 0.65. 相似文献
2.
V. S. Sudavtsova N. V. Kotova V. G. Kudin L. A. Romanova T. N. Zinevich 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2010,84(2):176-179
The partial mixing enthalpies of the components (Δm
$
\bar H
$
\bar H
i
) of the Ni-Ga melts were measured using the high-temperature isoperibolic calorimetry at 1770 ± 5 K in wide concentration
interval. The limiting partial mixing enthalpy of gallium in a liquid nickel (Δm
$
\bar H
$
\bar H
Ga∞) is −95.5 ± 19.8 kJ mol−1, and similar function of nickel in liquid gallium (Δm
$
\bar H
$
\bar H
Ni∞) is −74.5 ± 16.4 kJ mol−1. The integral mixing enthalpy of liquid alloys of this system was calculated from partial enthalpies for the whole concentration
area (Δm
H
min = −32.1 ± 2.7 kJ mol−1 at x
Ni = 0.5). The Δm
H value of liquid nickel-gallium alloys independence of the temperature is confirmed. Enthalpies of formation of liquid (Δm
H) phases of Ni-Ga system were compared with ones for solid (Δf
H) phases of this system. An analysis of d-metals influence on formation energy of Ga-d-Me melts was made using the values of Δf
H for intermediate phases of these systems. The article was translated by the authors. 相似文献
3.
V. S. Sudavtsova M. A. Shevchenko N. V. Kotova L. A. Romanova 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2011,85(1):1-8
The thermochemical properties of Al-Y melts were determined by isoperibolic calorimetry. It was established that the minimal
value of integral mixing enthalpies is equal to −40.8 + 0.4 kJ/mol at 1770 K and x
Y = 0.41. The thermodynamic properties of liquid alloys were modeled by the developed procedure using the coordinates of a
liquidus line in the phase diagram of the Al-Y system, and by the theory of ideal associated solutions. The component activities
exhibit high negative deviations from the Raoult law. The Gibbs energies of mixing of Al-Y melts have a minimum of −30.6 kJ/mol
at x
Y = 0.48. 相似文献
4.
B. A. Knyazev V. F. Vakher 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2011,85(5):804-810
The heats of the reaction of sodium with ethyl and methyl alcohol were determined by calorimetry. The difference in the standard
heats of the formation of triethylarsenite and arsenic trichloride was obtained by calorimetration of the reaction of arsenic
trichloride with sodium ethylate, the value of which was −382.42 ± 3.60 kJ/mol. The standard enthalpies of formation were
determined from a critical analysis of all data on thermochemistry of trialkylarsenites for the following compounds: triethylarsenite
Δf
H
298ℴ [(C2H5O)3As(liquid)] = (−704.38 ± 3.85) kJ/mol; trimethylarsenite Δf
H
298ℴ [(CH3O)3As(liquid)] = (−599.36 ± 1.88) kJ/mol. The values of standard enthalpies of formation were not adjusted for the following
substances in liquid state: arsenic trichloride (−321.96 ± 3.85 kJ/mol), tris-(diethylamido)arsenic(III) As(NEt2)3(liquid) (−129.81 ± 4.41 kJ/mol), tri-n-propylarsenite (−720.61 ± 4.49 kJ/mol), triisopropylarsenite (−756.11 ± 4.65 kJ/mol), tri-n-butylarsenite (−775.11 ± 4.53 kJ/mol), and triisobutylarsenite (−809.71 ± 4.59 kJ/mol). The use of sodium alcoxide solutions
for the calorimetration of halogen anhydrides of various acids was demonstrated. 相似文献
5.
V. N. Emel’yanenko S. P. Verevkin C. Schick E. N. Stepurko G. N. Roganov M. K. Georgieva 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2010,84(9):1491-1497
The enthalpies of combustion and formation of S-lactic acid at 298.15 K, Δc
H
mo(cr.) = −1337.9 ± 0.8 and Δf
H
mo(cr.) = −700.1 ± 0.9 kJ/mol, were determined by calorimetry. The temperature dependence of acid vapor pressure was studied
by the transpiration method, and the enthalpy of its vaporization was obtained, Δvap
H
o(298.15 K) = 69.1 ± 1.0 kJ/mol. The temperature and enthalpy of fusion, T
m (330.4 K) and Δm
H
o(298.15 K) = 14.7 ± 0.2 kJ/mol, were determined by differential scanning calorimetry. The enthalpy of formation of the acid
in the gas phase was obtained. Ab initio methods were used to perform a conformational analysis of the acid, calculate fundamental
vibration frequencies, moments of inertia, and total and relative energies of the stablest conformers. Thermodynamic properties
were calculated in the ideal gas state over the temperature range 0–1500 K. A thermodynamic analysis of mutual transformation
processes (the formation of SS- and RS(meso)-lactides from S-lactic acid and the racemization of these lactides) and the formation
of poly-(RS)-lactide from S-lactic acid and SS- and RS(meso)-lactides was performed. 相似文献
6.
M. R. Bisengalieva L. V. Mel’chakova L. P. Ogorodova M. F. Vigasina 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2010,84(9):1481-1484
A thermal and thermochemical study of natural aqueous hydroxyl-containing diorthosilicate, hemimorphite Zn4[Si2O7](OH)2 · H2O, was performed. The step character of its thermal decomposition was studied using FTIR spectroscopy. Melt solution calorimetry
was used to determine the enthalpies of formation from oxides Δf
H
OOX (298.15 K) = −69.3 ± 9.9 kJ/mol and elements {ie1481-2} (298.15 K) = −3864.3 ± 10.2 kJ/mol. 相似文献
7.
M. R. Bisengalieva L. P. Ogorodova M. F. Vigasina L. V. Mel’chakova 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2010,84(11):1838-1840
A calorimetric study of natural pyromorphite Pb5[PO4]3Cl was performed. Its enthalpy of formation was determined by melt solution calorimetry from elements Δf
H
el∘(298.15 K) = −4124 ± 20 kJ/mol. Value Δf
G
elo(298.15 K) = −3765 ± 20 kJ/mol was calculated. 相似文献
8.
Nonempirical methods are used to calculate the geometric parameters, the frequencies of normal vibrations, and thermochemical
characteristics of ions existing in saturated vapors over sodium bromide and iodide: Na2X+, NaX2−, Na3X2+, and Na2X3− (X = Br, I). According to the calculations, Na2X+ and NaX2− triatomic ions have a linear equilibrium configuration of D
∞h
symmetry. Pentaatomic ions can exist in the form of three isomers: linear with D
∞h
symmetry, planar cyclic with C
2v
symmetry, and bipyramidal with D
3h
symmetry. At a temperature of ∼1000 K, Na3X2+ and NaX3− pentaatomic ions are shown to be present in vapor mainly in the form of linear isomers. The energies and enthalpies of ion
molecular reactions with the participation of the above ions are calculated, and the formation enthalpies of the ions are
determined, Δ
f
H
o(0 K): 293±2 kJ/mol (Na2Br+), 354±2 kJ/mol (Na2I+), −536±2 kJ/mol (NaBr2−, −458±2 kJ/mol (NaI2−, 24±5 kJ/mol (Na3Br2+, 143±5 kJ/mol (Na3I2+, −810±5 kJ/mol (Na2Br3−, and −675±5 kJ/mol (Na2I3−. 相似文献
9.
L. P. Ogorodova I. A. Kiseleva 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2011,85(10):1857-1859
The standard dehydroxylation enthalpy of natural talc Mg3[Si4O10](OH)2 (87.8 ± 9.0 kJ/mol at 298.15 K) and the enthalpy of formation of dehydrated talc from the elements (Δf
H
elo (298.15 K) = −5527.0 ± 9.0 kJ/mol) were determined for the first time using Hess’s law, based on the total values of the
enthalpy increments in heating a sample from room temperature to 973 K and the enthalpies of dissolution at 973 K for dehydrated
talc measured in this work and those previously determined for talc and corresponding oxides. 相似文献
10.
M. F. Butman D. N. Sergeev V. B. Motalov L. S. Kudin A. S. Kryuchkov K. W. Krämer 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2011,85(6):922-925
A procedure for determining the formation enthalpies of LnX
n
(n = 1–3) molecules of thermally unstable lanthanide di- and trihalides that is based on measuring the equilibrium constants
of reactions in Ln-X systems of various content and solving a system of thermochemical equations is suggested. The procedure
is used to determine the enthalpies of formation Δf
H
298o of molecules and negative ions found in the vapors of ytterbium bromides: YbBr (20 ± 3), YbBr2 (−135 ± 10), YbBr3 (−233 ± 12), YbBr3− (−615 ± 31), and YbBr4− (−766 ± 23) kJ/mol. 相似文献
11.
Stefan Perişanu Iulia Contineanu Mircea D. Banciu Hui Zhao Nigam Rath James Chickos 《Structural chemistry》2006,17(6):639-648
Condensed and gas phase enthalpies of formation of 3:4,5:6-dibenzo-2-hydroxymethylene-cyclohepta-3,5-dienenone (1, (−199.1 ± 16.4), (−70.5 ± 20.5) kJ mol−1, respectively) and 3,4,6,7-dibenzobicyclo[3.2.1]nona-3,6-dien-2-one (2, (−79.7 ± 22.9), (20.1 ± 23.1) kJ mol−1) are reported. Sublimation enthalpies at T=298.15 K for these compounds were evaluated by combining the fusion enthalpies at T = 298.15 K (1, (12.5 ± 1.8); 2, (5.3 ± 1.7) kJ mol−1) adjusted from DSC measurements at the melting temperature (1, (T
fus, 357.7 K, 16.9 ± 1.3 kJ mol−1)); 2, (T
fus, 383.3 K, 10.9 ± 0.1) kJ mol−1) with the vaporization enthalpies at T = 298.15 K (1, (116.1 ± 12.1); 2, (94.5 ± 2.2) kJ mol−1) measured by correlation-gas chromatography. The vaporization enthalpies of benzoin ((98.5 ± 12.5) kJ mol−1) and 7-heptadecanone ((94.5 ± 1.8) kJ mol−1) at T = 298.15 K and the fusion enthalpy of phenyl salicylate (T
fus, 312.7 K, 18.4 ± 0.5) kJ mol−1) were also determined for the correlations. The crystal structure of 1 was determined by X-ray crystallography. Compound
1 exists entirely in the enol form and resembles the crystal structure found for benzoylacetone. 相似文献
12.
R. P. Tarasov A. V. Volkov M. I. Bazanov A. S. Semeikin 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2009,83(5):868-869
The energy of combustion of cobalt tetrakis(4-metoxyphenyl)porphin was determined in an isothermic-shell liquid calorimeter
with a stationary calorimetric bomb. The standard enthalpies of combustion and formation of the complex were calculated, −Δ
c
H
o = 27334.06 ± 50.98 kJ/mol and Δf
H
o = 3062.90 ± 50.97 kJ/mol.
Original Russian Text ? R.P. Tarasov, A.V. Volkov, M.I. Bazanov, A.S. Semeikin, 2009, published in Zhurnal Fizicheskoi Khimii,
2009, Vol. 83, No. 5, pp. 993–995. 相似文献
13.
V. P. Kheidorov Yu. A. Ershov G. Yu. Chalyi O. V. Titorovich 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2011,85(8):1358-1362
The kinetics of the oxidative conversion of 1,3,7-trimethylxanthine upon treatment with hypochlorite ions (OCl−) in aqueous medium at 283–298 K and pH 8.2 was studied. The reaction order with respect to each component was determined
and proved to be 1. It was established that the temperature dependence of the reaction rate follows the Arrhenius equation.
The activation parameters of the reaction were measured: E
a
= 33.58 kJ/mol, ΔH
≠ = 31.12 kJ/mol, ΔS
≠ = −170.02 J/(K mol), ΔG
≠ = 81.45 kJ/mol. The stoichiometry of the reaction was studied, and the chemistry of the oxidative conversion of caffeine
treated with OCl− is discussed. 相似文献
14.
M. F. Butman L. S. Kudin V. B. Motalov D. A. Ivanov V. V. Sliznev K. W. Krämer 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2008,82(5):767-772
The thermodynamic stability of the LaBr 4 ? anion was for the first time studied by high-temperature mass spectrometry and nonempirical quantum-chemical methods. The experimental and theoretical enthalpies of the reaction $ LaBr_4^ - = Br^ - + LaBr_3 The thermodynamic stability of the LaBr4− anion was for the first time studied by high-temperature mass spectrometry and nonempirical quantum-chemical methods. The
experimental and theoretical enthalpies of the reaction were Δr
H°(298.15 K) = 302 ± 14 and 303 kJ/mol, respectively. The value Δf
H° (LaBr4−, g, 298.15 K) = −1105 ± 14 kJ/mol was recommended as the enthalpy of formation of the LaBr4− anion.
Original Russian Text ? M.F. Butman, L.S. Kudin, V.B. Motalov, D.A. Ivanov, V.V. Sliznev, K.W. Kr?mer, 2008, published in
Zhurnal Fizicheskoi Khimii, 2008, Vol. 82, No. 5, pp. 885–890. 相似文献
15.
The relative enthalpies, ΔHo (0) and ΔHo (298.15), of stationary points (four minimum and three transition structures) on the •O3H potential energy surface were calculated with the aid of the G3MP2B3 as well as the CCSD(T)–CBS (W1U) procedures from which
we earlier found mean absolute deviations (MAD) of 3.9 kJ mol−1 and 2.3 kJ mol−1, respectively, between experimental and calculated standard enthalpies of the formation of a set of 32 free radicals. For
CCSD(T)-CBS (W1U) the well depth from O3 + H• to trans-•O3H, ΔHowell(298.15) = −339.1 kJ mol−1, as well as the reaction enthalpy of the overall reaction O3 + H•→O2 + •OH, ΔrHo(298.15) = −333.7 kJ mol−1, and the barrier of bond dissociation of trans-•O3H → O2 + •OH, ΔHo(298.15) = 22.3 kJ mol−1, affirm the stable short-lived intermediate •O3H. In addition, for radicals cis-•O3H and trans-•O3H, the thermodynamic functions heat capacity Cop(T), entropy So (T), and thermal energy content Ho(T) − Ho(0) are tabulated in the range of 100 − 3000 K. The much debated calculated standard enthalpy of the formation of the trans-•O3H resulted to be ΔfHo(298.15) = 31.1 kJ mol −1 and 32.9 kJ mol −1, at the G3MP2B3 and CCSD(T)-CBS (W1U) levels of theory, respectively. In addition, MR-ACPF-CBS calculations were applied
to consider possible multiconfiguration effects and yield ΔfHo(298.15) = 21.2 kJ mol −1. The discrepancy between calculated values and the experimental value of −4.2 ± 21 kJ mol−1 is still unresolved.
Note added in proof: Yu-Ran Luo and J. Alistair Kerr, based on the discussion in reference 12, recently presented an experimental
value of ΔfHo(298.15) = 29.7 ± 8.4 kJ mol−1 in the 85th edition of the CRC Handbook of Chemistry and Physics (in progress). 相似文献
16.
Polymorphism of paracetamol 总被引:1,自引:0,他引:1
G. L. Perlovich Tatyana V. Volkova Annette Bauer-Brandl 《Journal of Thermal Analysis and Calorimetry》2007,89(3):767-774
The thermodynamic relationship between crystal modifications of paracetamol was studied by alternative methods. Temperature
dependence of saturated vapor pressure for polymorphic modifications of the drug paracetamol (acetaminophen) was mea sured
and thermodynamic functions of the sublimation process calculated. Solution calorimetry was carried out for the two modifications
in the same solvent. Thermodynamic parameters for sublimation for form I (monoclinic) were found: ΔG
sub298=60.0 kJ mol−1; ΔH
sub298=117.9±0.7 kJ mol−1; ΔS
sub298=190±2 J mol−1 K−1. For the orthorhombic modification (form II), the saturated vapor pressure could only be studied at 391 K. Phase transition
enthalpy at 298 K, ΔH
tr298(I→II)=2.0±0.4 kJ mol−1, was derived as the difference between the solution enthalpies of the noted polymorphs in the same solution (methanol). Based
on ΔH
tr298 (I→II), differences between temperature dependencies of heat capacities of both modifications and the vapor pressure value
of form II at 391 K, the temperature dependence of saturated vapor pressure and thermodynamic sublimation parameters for modification
II were also estimated (ΔG
sub298=56.1 kJ mol−1; ΔH
sub298=115.9±0.9 kJ mol−1; ΔS
sub298=200±3 J mol−1 K−1). The results indicate that the modifications are monotropically related, which is in contrast to findings recently reported
found by classical thermochemical methods. 相似文献
17.
Wincel H 《Journal of the American Society for Mass Spectrometry》2011,22(9):1570-1576
The thermochemical properties ΔH
o
n
, ΔS
o
n
, and ΔG
o
n
for the hydration of sodiated and potassiated monosaccharides (Ara = arabinose, Xyl = xylose, Rib = ribose, Glc = glucose,
and Gal = galactose) have been experimentally studied in the gas phase at 10 mbar by equilibria measurements using an electrospray
high-pressure mass spectrometer equipped with a pulsed ion beam reaction chamber. The hydration enthalpies for sodiated complexes
were found to be between −46.4 and −57.7 kJ/mol for the first, and −42.7 and −52.3 kJ/mol for the second water molecule. For
potassiated complexes, the water binding enthalpies were similar for all studied systems and varied between −48.5 and −52.7
kJ/mol. The thermochemical values for each system correspond to a mixture of the α and β anomeric forms of monosaccharide
structures involved in their cationized complexes. 相似文献
18.
M. A. Shevchenko M. I. Ivanov V. V. Berezutski V. G. Kudin V. S. Sudavtsova 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2012,86(12):1779-1784
Partial and integral mixing enthalpies of melts of binary systems Mn-Sc and Mn-Y at 1873 and 1830 K, respectively, are determined by calorimetry. It is found that the minima of the mixing enthalpies are ?7.1 ± 0.4 and -3.2 ± 0.2 kJ/mol at x Mn = 0.60 and 0.61, respectively. The initial partial mixing enthalpies of Sc and Y are ?33.2 ± 2.1 and ?16.6 ± 0.8 kJ/mol, respectively. The thermodynamic properties of melts of binary Mn-Sc(Y) systems are calculated using the ideal associated solution (IAS) model. It is found that the activities of the components exhibit slight negative deviations from the ideal solutions, and the excess Gibbs energies reach ?3.0 and ?1.6 kJ/mol, respectively. 相似文献
19.
Relative enthalpies for low-and high-temperature modifications of Na3FeF6 and for the Na3FeF6 melt have been measured by drop calorimetry in the temperature range 723–1318 K. Enthalpy of modification transition at 920
K, δtrans
H(Na3FeF6, 920 K) = (19 ± 3) kJ mol−1 and enthalpy of fusion at the temperature of fusion 1255 K, δfusH(Na3FeF6, 1255 K) = (89 ± 3) kJ mol−1 have been determined from the experimental data. Following heat capacities were obtained for the crystalline phases and for
the melt, respectively: C
p(Na3FeF6, cr, α) = (294 ± 14) J (mol K)−1, for 723 = T/K ≤ 920, C
p(Na3FeF6, cr, β) = (300 ± 11) J (mol K)−1 for 920 ≤ T/K = 1233 and C
p(Na3FeF6, melt) = (275 ± 22) J (mol K)−1 for 1258 ≤ T/K ≤ 1318. The obtained enthalpies indicate that melting of Na3FeF6 proceeds through a continuous series of temperature dependent equilibrium states, likely associated with the production of
a solid solution.
相似文献
20.
L. Peng X. Jiangjun M. Fangquan L. Xi Z. Chaocan 《Journal of Thermal Analysis and Calorimetry》2008,93(2):485-488
The standard molar enthalpy of combustion of cholesterol was measured at constant volume. According to value of Δr
U
mθ(−14358.4±20.65 kJ mol−1), Δr
H
mθ(−14385.7 kJ mol−1) of combustion reaction and Δf
H
mθ(2812.9 kJ mol−1) of cholesterol were obtained from the reaction equation. The enthalpy of combustion reaction of cholesterol was also estimated
by the average bond enthalpies. By design of a thermo-chemical recycle, the enthalpy of combustion of cholesterol were calculated
between 283.15∼373.15 K. Besides, molar enthalpy and entropy of fusion of cholesterol was obtained by DSC technique. 相似文献