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1.
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
2.
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
3.
V. N. Belyaev N. L. Lebedeva 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2012,86(6):920-928
Sr+ + H2O ↔ SrOH+ + H equilibrium was studied spectrophotometrically. This reaction occurs in natural gas combustion products. Its enthalpy
Δr
H
○(0) = 61.4 ± 2.8 kJ/mol and bond energy D
0(Sr+-OH) = 432.6 ± 2.8 kJ/mol were determined using the third law of thermodynamics. The experimental data on this reaction obtained
earlier in hydrogen flames, Δr
H
○(0) = 55.3 ± 10.6 and D
0(Sr+-OH) = 438.7 ± 10.6 kJ/mol, were interpreted anew. The D
0(Sr+-OH) = 432.8 ± 2.7 kJ/mol value was eventually obtained. 相似文献
4.
The novel ternary solid complex Gd(C5H8NS2)3(C12H8N2) has been obtained from the reaction of hydrous gadolinium chloride, ammonium pyrrolidinedithiocarbamate (APDC), and 1,10-phenanthroline
(o-phen · H2O) in absolute ethanol. The complex was described by an elemental analysis, TG-DTG, and an IR spectrum. The enthalpy change
of the complex formation reaction from a solution of the reagents, Δr
H
m
ϑ
(sol), and the molar heat capacity of the complex, c
m
, were determined as being − 15.174 ± 0.053 kJ/mol and 72.377 ± 0.636 J/(mol K) at 298.15 K by using an RD496-III heat conduction
microcalorimeter. The enthalpy change of a complex formation from the reaction of the reagents in a solid phase, Δr
H
m
ϑ
(s), was calculated as being 52.703 ± 0.304 kJ/mol on the basis of an appropriate thermochemical cycle and other auxiliary
thermodynamic data. The thermodynamics of the formation reaction of the complex was investigated by the reaction in solution.
Fundamental parameters, the activation enthalpy (ΔH
≠
ϑ
), the activation entropy (ΔS
≠
ϑ
), the activation free energy (ΔG
≠
ϑ
), the apparent reaction rate constant (k), the apparent activation energy (E), the preexponential constant (A), and the reaction order (n), were obtained by the combination of the thermochemical data of the reaction and kinetic equations, with the data of thermokinetic
experiments. The constant-volume combustion energy of the complex, Δc
U, was determined as being −17588.79 ± 8.62 kJ/mol by an RBC-II type rotatingbomb calorimeter at 298.15 K. Its standard enthalpy
of combustion, Δc
H
m
ϑ
, and standard enthalpy of formation, Δf
H
m
ϑ
, were calculated to be −17604.28 ± 8.62 and −282.43 ± 9.58 kJ/mol, respectively.
The text was submitted by the authors in English. 相似文献
5.
N. N. Smirnova T. A. Bykova N. A. Polotnyanko N. D. Shikina I. L. Khodakovskii 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2010,84(11):1851-1855
The temperature dependence of the heat capacity C
p
o = f(T) of palladium oxide PdO(cr.) was studied for the first time in an adiabatic vacuum calorimeter in the range of 6.48–328.86
K. Standard thermodynamic functions C
p
o(T), H
o(T) — H
o(0), S
o(T), and G
o(T) — H
o(0) in the range of T → 0 to 330 K (key quantities in different thermodynamic calculations with the participation of palladium compounds) were
calculated on the basis of the experimental data. Based on an analysis of studies on determining the thermodynamic properties
of PdO(cr.), the following values of absolute entropy, standard enthalpy, and Gibbs function of the formation of palladium
oxide are recommended: S
o(298.15) = 39.58 ± 0.15 J/(K mol), Δf
H
o(298.15) = −112.69 ± 0.32 kJ/mol, Δf
G
o(298.15) = −82.68 ± 0.35 kJ/mol. The stability of Pd(OH)2 (amorph.) with respect to PdO(cr.) was estimated. 相似文献
6.
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
7.
G. Xie S. P. Chen S. L. Gao X. X. Meng Q. Z. Shi 《Journal of Thermal Analysis and Calorimetry》2006,83(3):693-700
A novel solid complex, formulated as Ho(PDC)3
(o-phen), has been obtained from the reaction
of hydrate holmium chloride, ammonium pyrrolidinedithiocarbamate (APDC) and
1,10-phenanthroline (o-phen·H2O)
in absolute ethanol, which was characterized by elemental analysis, TG-DTG
and IR spectrum. The enthalpy change of the reaction of complex formation
from a solution of the reagents, ΔrHmθ (sol), and the molar heat capacity of the complex, cm,
were determined as being –19.161±0.051 kJ mol–1
and 79.264±1.218 J mol–1 K–1
at 298.15 K by using an RD-496 III heat conduction microcalorimeter. The enthalpy
change of complex formation from the reaction of the reagents in the solid
phase, ΔrHmθ(s), was calculated as
being (23.981±0.339) kJ mol–1 on the
basis of an appropriate thermochemical cycle and other auxiliary thermodynamic
data. The thermodynamics of reaction of formation of the complex was investigated
by the reaction in solution at the temperature range of 292.15–301.15
K. The constant-volume combustion energy of the complex, ΔcU, was determined as being –16788.46±7.74
kJ mol–1 by an RBC-II type rotating-bomb
calorimeter at 298.15 K. Its standard enthalpy of combustion, ΔcHmθ, and standard enthalpy of formation,
ΔfHmθ, were calculated to be –16803.95±7.74 and –1115.42±8.94
kJ mol–1, respectively. 相似文献
8.
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
9.
Thermochemical
studies on the thioproline 总被引:3,自引:0,他引:3
The combustion energy of thioproline was determined
by the precision rotating-bomb calorimeter at 298.15 K to be Δc
U= –2469.30±1.44 kJ mol–1.
From the results and other auxiliary quantities, the standard molar enthalpy
of combustion and the standard molar enthalpy of formation of thioproline
were calculated to be Δc
H
m
θC4H7NO2S,
(s), 298.15 K= –2469.92±1.44 kJ mol–1
and Δf
H
m
θC4H7NO2S, (s), 298.15K= –401.33±1.54
kJ mol–1. 相似文献
10.
V. N. Belyaev N. L. Lebedeva 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2010,84(11):1841-1850
Using the third law of thermodynamics, we found the enthalpy Δr
H
o(0) = 71 ± 7 of the reaction Eu+ + H2O ↔ EuOH+ + H and the binding energies D
0(Eu+-OH) = 423 ± 7 and D
0(Eu-OH) = 389 ± 11 (kJ/mol). To determine the latter, we additionally used the ionization potential I
0(EuOH) = 5.32 ± 0.08 eV found using the Stark intramolecular effect. 相似文献
11.
G. V. Girichev V. V. Rybkin V. V. Tyunina A. V. Krasnov N. V. Tverdova N. P. Kuz’mina I. G. Zaitseva 《Russian Journal of Inorganic Chemistry》2011,56(1):99-103
A mass spectrometric study of the saturated vapor over ytterbium tris(hexafluoroacetylacetonate) Yb(hfa)3 (hfa = CF3-C(O)-CH-C(O)-CF3) and of the vapor overheated up to the thermal decomposition temperature of the complex is presented. The vapor composition
changes markedly with increasing temperature. At T ≈ 370 K, the mass spectrum of the vapor over Yb(hfa)3 indicates the presence of ions containing one to three metal atoms. As the temperature is raised, the ion currents due to
oligomer ions decrease. The oligomers are not detected at T > 440 K. The total decomposition temperature of Yb(hfa)3 is 663(9) K. The second-law enthalpy of sublimation (ΔH
so (380 K)) is 134 ± 7 kJ/mol for the monomer and 138 ± 10 kJ/mol for the dimer. The enthalpy of dissociation of the dimer into
monomer molecules is nearly equal to the enthalpy of sublimation of the monomer and dimer: ΔH
dis(380 K) = 130 ± 15 kJ/mol. 相似文献
12.
Pascale Bénézeth Donald A. Palmer David J. Wesolowski 《Journal of solution chemistry》1997,26(1):63-84
The three molal dissociation quotients for citric acid were measured potentiometrically with a hydrogen-electrode concentration
cell from 5 to 150°C in NaCl solutions at ionic strengths of 0.1, 0.3, 0.6, and 1 molal. The molal dissociation quotients
and available literature data at infinite dilution were fitted by empirical equations in the all-anionic form involving an
extended Debye-Hückel term and up to five adjustable parameters involving functions of temperature and ionic strength. This
treatment yielded the following thermodynamic quantitites for the first dissociation equilibrium at 25°C: logK
1a=−3.127±0.002, ΔH
1a
o
=4.1±0.2 kJ-mol−1, ΔS
1a
o
=−46.3±0.7 J-K−1-mol−1, and ΔCp
1a
o
=−162±7 J-K−1-mol−1; for the second acid dissociation equilibrium at 25°C: logK
2a
=−4.759±0.001, ΔH
2a
o
=2.2±0.1, ΔS
2a
o
=−83.8±0.4, and ΔCp
2a
o
=−192±15, and for the third dissociation equilibrium at 25°C: logK
3a=−6.397±0.002, ΔH
3a
o
=−3.6±0.2, ΔS
3a
o
=−134.5±0.7, and ΔCp
3a
o
=−231±7. 相似文献
13.
S. P. Chen X. X. Meng Q. Shuai B. J. Jiao S. L. Gao Q. Z. Shi 《Journal of Thermal Analysis and Calorimetry》2006,86(3):767-774
A
solid complex Eu(C5H8NS2)3(C12H8N2) has been obtained from reaction of
hydrous europium chloride with ammonium pyrrolidinedithiocarbamate (APDC)
and 1,10-phenanthroline (o-phen⋅H2O)
in absolute ethanol. IR spectrum of the complex indicated that Eu3+
in the complex coordinated with sulfur atoms from the APDC and nitrogen atoms
from the o-phen. TG-DTG investigation provided
the evidence that the title complex was decomposed into EuS.
The
enthalpy change of the reaction of formation of the complex in ethanol, Δr
H
m
θ(l), as –22.214±0.081 kJ mol–1,
and the molar heat capacity of the complex, c
m,
as 61.676±0.651 J mol–1 K–1,
at 298.15 K were determined by an RD-496 III type microcalorimeter. The enthalpy
change of the reaction of formation of the complex in solid, Δr
H
m
θ(s), was calculated as 54.527±0.314 kJ mol–1
through a thermochemistry cycle. Based on the thermodynamics and kinetics
on the reaction of formation of the complex in ethanol at different temperatures,
fundamental parameters, including the activation enthalpy (ΔH
≠
θ),
the activation entropy (ΔS
≠
θ),
the activation free energy (ΔG
≠
θ),
the apparent reaction rate constant (k),
the apparent activation energy (E), the
pre-exponential constant (A) and the reaction
order (n), were obtained. The constant-volume
combustion energy of the complex, Δc
U,
was determined as –16937.88±9.79 kJ mol–1
by an RBC-II type rotating-bomb calorimeter at 298.15 K. Its standard enthalpy
of combustion, Δc
H
m
θ,
and standard enthalpy of formation, Δf
H
m
θ,
were calculated to be –16953.37±9.79 and –1708.23±10.69
kJ mol–1, respectively. 相似文献
14.
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
15.
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
16.
M. R. Bissengaliyeva D. B. Gogol’ N. S. Bekturganov 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2011,85(2):157-163
The heat capacity of natural mineral, pyromorphite Pb5(PO4)3Cl, was measured over the temperature range 4.2–320 K using low-temperature adiabatic calorimetry. An anomalous temperature
dependence of heat capacity with a maximum at 273.24 K was observed between 250 and 290 K. The heat capacity, entropy, enthalpy,
and reduced thermodynamic potential of pyromorphite were calculated and tabulated over the temperature range 5–320 K. The
standard thermodynamic functions of the mineral are C
p298.15o = 414.98 ± 0.44 J/(mol K), S
298.15o = 585.31 ± 0.99 J/(mol K), H
298.15o − H
0o = 80.90 ± 0.08 kJ/mol, and Φ298.15o = 313.97 ± 0.84 J/(mol K). 相似文献
17.
S. N. Solov’yov A. A. Firer A. Ya. Dupal 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2009,83(4):689-691
The enthalpies of interaction of (XeF5)2[MnF6](cr) with a 0.0524 m solution of KOH and a 0.0300 m solution of H2SO4, the enthalpy of solution of KMnO4(cr) in a 0.0440 m solution of KOH, and the enthalpy of mixing of aqueous KF with alkaline KMnO4 were measured in isothermic-shell calorimeters at 298.15 K. The standard enthalpy of formation of the compound at 298.15
K was calculated by two independent procedures using the experimental values and literature data (Δf
H
o = −1185 ± 18 kJ/mol).
Original Russian Text ? S.N. Solov’yov, A.A. Firer, A.Ya. Dupal, 2009, published in Zhurnal Fizicheskoi Khimii, 2009, Vol.
83, No. 4, pp. 798–800. 相似文献
18.
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
19.
A. D. Chervonnyi 《Russian Journal of Inorganic Chemistry》2010,55(4):556-559
The A1, O, AlO, A12O, Al2O2, WO2, and WO3, partial pressures in the vapor over Al2O3 in a tungsten Knudsen effusion cell between 2300 and 2600 K were derived from A1+, O+, AlO+, A12O+, Al2O2+, WO2+, and WO3+, ion intensities. The mass spectrometer was calibrated against the equilibrium constant of the WO3(g) = WO2(g) + O(g) reaction. Refined values of the ionization cross sections of AlO and A12O2 were used in the partial pressure calculations. The enthalpies of atomization of aluminum suboxides were determined to be
Δat
H
o(AlO, g, 0) = 510.7 ± 3.3 kJ mol−1, Δat
H
o(Al2O, g, 0) = 1067.2 ± 6.9 kJ mol−1, and Δat
H
o(Al2O2, g, 0) = 1556.7 ± 9.9 kJ mol−1. 相似文献
20.
Y. Xu-Wu Z. Hang-Guo S. Wu-Juan W. Xiao-Yan G. Sheng-Li 《Journal of Thermal Analysis and Calorimetry》2008,92(3):961-965
The copper(II) complex of 6-benzylaminopurine (6-BAP) has been prepared with dihydrated cupric chloride and 6-benzylaminopurine.
Infrared spectrum and thermal stabilities of the solid complex have been discussed. The constant-volume combustion energy,
Δc
U, has been determined as −12566.92±6.44 kJ mol−1 by a precise rotating-bomb calorimeter at 298.15 K. From the results and other auxiliary quantities, the standard molar enthalpy
of combustion, Δc
H
m
θ, and the standard molar of formation of the complex, Δf
H
m
θ, were calculated as −12558.24±6.44 and −842.50±6.47 kJ mol−1, respectively. 相似文献