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1.
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
2.
Wenshen C. Yi L. Chuanpei Z. Songsheng Q. 《Journal of Thermal Analysis and Calorimetry》2001,66(2):463-468
The solid-state coordination reaction: Nd(NO3)3·6H2O(s)+4Ala(s) → Nd(Ala)4(NO3)3·H2O(s)+5H2O(l) and Er(NO3)3·6H2O(s)+4Ala(s) → Er(Ala)4(NO3)3·H2O(s)+5H2O(l) have been studied by classical solution calorimetry. The molar dissolution enthalpies of the reactants and the products
in 2 mol L–1 HCl solvent of
these two solid-solid coordination reactions have been measured using a calorimeter. From the results and other auxiliary
quantities, the standard molar formation enthalpies of [Nd(Ala)4(NO3)3·H2O, s, 298.2 K] and[Er(Ala)4(NO3)3·H2O, s,298.2 K] at 298.2 K have been determined to be Δf
H
m
0 [Nd(Ala)4(NO3)3·H2O,s, 298.2 K]=–3867.2 kJ mol–1, and Δf
H
m
0 [Er(Ala)4(NO3)3·H2O, s, 298.2 K]=–3821.5 kJ mol–1.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
3.
The stepwise acid dissociation constants for p-benzohydroquinone (QH2) in aqueous media have been explicitly calculated for the first time, with the INDO parametrized SCF –MO method. We have optimized the geometries of QH2, QH?, and Q2? and of the QH2 · 6H2O, QH? · (H3O+) · 5H2O, and Q2? · (H3O+)2 · 4H2O systems that model the solvated species. The presence of the associated water molecules (and hydronium ions) account for the stabilization due to hydrogen bonding as well as for a part of the effect of interaction of these molecules with the respective reaction fields in an aqueous medium. To simulate the first solvation shell in a more complete manner, four more water molecules have been considered to be placed above and below the quinonoid ring and the optimized geometries of the resulting hydrated species, QH2 · 10H2O, QH? · (H3O+) · 9H2O, and QH? · (H3O+) · 8H2O, have been determined. The standard free-energy changes calculated for the dissociation of QH2 into QH? and H+ is 0.0251 Hartree (65.9 kJ mol?1) and that of QH? into Q2? and H+ is 0.0285 Hartree (74.8 kJ mol?1). Experimentally observed dissociation constants for these two steps correspond to free-energy changes of 0.0214 Hartree (56.2 kJ mol?1) and 0.0248 Hartree (65.1 kJ mol?1), respectively. © 1995 John Wiley & Sons, Inc. 相似文献
4.
Y. R. Zhao J. X. Dong Y. Liu S. S. Qu 《Journal of Thermal Analysis and Calorimetry》2007,90(2):565-568
The two complexes, [RE(Gly)4(Im)(H2O)](ClO4)3(s)(RE = Eu, Sm), have been synthesized and characterized. The standard molar enthalpies of reaction for the following reactions,
RECl3·6H2O(s)+4Gly(s)+Im(s)+3NaClO4(s) = =[RE(Gly)4(Im)(H2O)](ClO4)3(s)+3NaCl(s)+5H2O(l), were determined by solution-reaction colorimetry. The standard molar enthalpies of formation of the two complexes at
T = 298.15 K were derived as Δf
H
mΘ {Eu(Gly)4(Im)(H2O)}(ClO4)3(s)} = = −(3396.6±2.3) kJ mol−1 and Δf
H
mΘ {Sm(Gly)4(Im)(H2O)}(ClO4)3(s)} = −(3472.7±2.3) kJ mol−1, respectively. 相似文献
5.
V. A. Lukyanova T. S. Papina K. V. Didenko A. S. Alikhanyan 《Journal of Thermal Analysis and Calorimetry》2008,92(3):743-746
The standard enthalpy of combustion of crystalline silver pivalate, (CH3)3CC(O)OAg (AgPiv), was determined in an isoperibolic calorimeter with a self-sealing steel bomb, Δc
H
0 (AgPiv, cr)= −2786.9±5.6 kJ mol−1. The value of standard enthalpy of formation was derived for crystalline state: Δf
H
0(AgPiv,cr)= −466.9±5.6 kJ mol−1. Using the enthalpy of sublimation, measured earlier, the enthalpy of formation of gaseous dimer was obtained: Δf
H
0(Ag2Piv2,g)= −787±14 kJ mol−1. The enthalpy of reaction (CH3)3CC(O)OAg(cr)=Ag(cr)+(CH3)3CC(O)O.(g) was estimated, Δr
H
0=202 kJ mol−1. 相似文献
6.
Wen-Sheng C. Yi L. Chuan-Pei Z. Qiang-Guo L. Song-Sheng Q. 《Journal of Thermal Analysis and Calorimetry》2003,73(1):285-291
The solid-state coordination reactions of lanthanum chloride with alanine and glycine, and lanthanum nitrate with alanine
have been studied by classical solution calorimetry. The molar dissolution enthalpies of the reactants and the products in
2 mol L-1 HCl solvent of these three solid-solid coordination reactions have been measured using an isoperibol calorimeter. From the
results and other auxiliary quantities, the standard molar formation enthalpies have been determined to be Δf
H
m
θ[La(Ala)3Cl3·3H2O(s), 298.2 K]= -3716.3 kJ mol-1, Δf
H
m
θ [La(Gly)3Cl3·5H2O(s), 298.2 K]= -4223.0 kJ mol-1 and Δf
H
m
θ [La(Ala)4(NO3)3·H2O(s), 298.2 K]= -3867.57 kJ mol-1, respectively.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
7.
Y. Y. Di Z. C. Tan L. W. Li S. L. Gao L. X. Sun 《Journal of Thermal Analysis and Calorimetry》2007,87(2):545-551
Low-temperature heat capacities of a solid
complex Zn(Val)SO4·H2O(s) were measured by a precision automated adiabatic
calorimeter over the temperature range between 78 and 373 K. The initial dehydration
temperature of the coordination compound was determined to be, T
D=327.05
K, by analysis of the heat-capacity curve. The experimental values of molar
heat capacities were fitted to a polynomial equation of heat capacities (C
p,m) with the reduced temperatures
(x), [x=f (T)], by least
square method. The polynomial fitted values of the molar heat capacities and
fundamental thermodynamic functions of the complex relative to the standard
reference temperature 298.15 K were given with the interval of 5 K.
Enthalpies of dissolution of the [ZnSO4·7H2O(s)+Val(s)] (Δsol
H
m,l
0)
and the Zn(Val)SO4·H2O(s) (Δsol
H
m,2
0) in 100.00 mL of 2 mol dm–3 HCl(aq) at T=298.15
K were determined to be, Δsol
H
m,l
0=(94.588±0.025) kJ mol–1 and Δsol
H
m,2
0=–(46.118±0.055)
kJ mol–1, by means of a homemade isoperibol
solution–reaction calorimeter. The standard molar enthalpy of formation
of the compound was determined as: Δf
H
m
0
(Zn(Val)SO4·H2O(s), 298.15 K)=–(1850.97±1.92) kJ mol–1,
from the enthalpies of dissolution and other auxiliary thermodynamic data
through a Hess thermochemical cycle. Furthermore, the reliability of the Hess
thermochemical cycle was verified by comparing UV/Vis spectra and the refractive
indexes of solution A (from dissolution of the [ZnSO4·7H2O(s)+Val(s)] mixture
in 2 mol dm–3 hydrochloric acid) and solution
A’ (from dissolution of the complex Zn(Val)SO4·H2O(s) in 2 mol dm–3
hydrochloric acid). 相似文献
8.
R. Srikanth K. Bhanuprakash R. Srinivas Cathy Y. Wong Johan K. Terlouw 《Journal of mass spectrometry : JMS》2004,39(3):303-311
Protonated silanoic acid, HSi(OH)2+, 1a +, is cleanly generated by the dissociative electron ionization of triethoxysilane, HSi(OC2H5)3, and tetraethoxysilane, Si(OC2H5)4. This follows from tandem mass spectrometric experiments and CBS-QB3 model chemistry calculations. The calculations predict that 1a + (ΔHf(298 K) = 205 kJ mol−1) is separated by high barriers from its isomers HOSiOH2+, 1b + and HSi(O)OH2+, 1c +. Low-energy (metastable) ions 1a + dissociate by loss of H2O via the pathway 1a + → 1b + → SiOH+ + H2O. Analysis of the metastable peak for this process confirms that the isomerization step 1a + → 1b + is rate determining. The calculations further predict that the incipient ions 1b + communicate via a low barrier with the proton-bound dimer SiO···H···OH2+, 1d +. This dimer ion is much lower in energy than its counterpart OSi···H···OH2+, 1e +, which is calculated to be only marginally stable. A comparison of the potential energy diagram for the silicon-containing ions 1a +– 1e + with that of their carbon analogues reveals that the dissociation chemistries of HSi(OH)2+ and HC(OH)2+ are only superficially similar. Neutralization–reionization experiments confirm the theoretical prediction that the HSi(OH)2• radical (ΔHf(298 K) = −455 kJ mol−1) is a stable species in the rarefied gas phase. However, owing to a mismatch of Franck–Condon factors a large fraction of the neutralized ions dissociates by loss of H• yielding Si(OH)2. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
9.
Y. M. Dan Y. R. Zhao Y. Liu S. S. Qu 《Journal of Thermal Analysis and Calorimetry》2006,84(3):531-534
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 (39.26±0.10)
and (5.33±0.12) kJ mol–1 , respectively.
Standard enthalpies of formation of the two complexes at T=298.15
K, ΔfHΘm
{[Ln(Ala)2(Im)(H2O)](ClO4)3(s)} (Ln=Pr, Gd),
were calculated as –(2424.2±3.3) and –(2443.4±3.3)
kJ mol–1 , respectively. 相似文献
10.
A. N. Zakharov A. F. Maiorova A. N. Kharlanov K. B. Kalmykov 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2011,85(10):1679-1688
Nanoparticles of NiC2O4 · 2H2O were obtained within the interspheric voids of synthetic opal polycrystalline samples based on SiO2. The thermal decomposition of NiC2O4 · 2H2O inclusions within the pores of crystallites was studied by means of thermal gravimetry and differential scanning calorimetry
under static conditions in atmospheres of He and air. The efficient activation energy of dehydration (180 ± 10 kJ mol−1) and dehydration enthalpy of nickel oxalate crystalline hydrate (69.9 kJ mol−1) within the pores of photonic crystals based on SiO2 were calculated. Pyrolysis of the nickel oxalate led to the formation
of NiO nanoparticles within the voids and on the external surface of the photonic crystallites. The behavior of polycrystalline
samples of the photonic crystals in a medium of immersion liquids was studied. It was shown that the partial population of
the interspheric pores of photonic crystals with NiC2O4 · 2H2O, NiO, and Ni that diffuse visible light do not lead to a total loss of light conductivity in the immersion medium. The diffuse
reflection spectra of a sample of photonic crystals populated with NiC2O4 · 2H2O and NiO phases were recorded. A sample of photonic crystals with inclusions of metallic nickel particles exhibiting magnetic
properties was obtained by treating nickel oxide-containing synthetic opal based on SiO2 with molecular hydrogen. 相似文献
11.
The thermal decomposition of tribochemically activated Al2(SO4)3·xH2O was studied by TG, DTA and EMF methods. For some of the intermediate solids, X-ray diffraction and IR-spectroscopy were applied to learn more about the reaction mechanism. Thermal and EMF studies confirmed that, even after mechanical activation of Al2(SO4)3·xH2O, Al2O(SO4)2 is formed as an intermediate. Isothermal kinetic experiments demonstrated that the thermochemical sulphurization of inactivated Al2(SO4)3·xH2O has an activation energy of 102.2 kJ·mol?1 in the temperature range 850–890 K. The activation energy for activated Al2(SO4)3·xH2O in the range 850–890 K is 55.0 kJ·mol?1. The time of thermal decomposition is almost halved when Al2(SO4)3·xH2O is activated mechanically. The results permit conclusions concerning the efficiency of the tribochemical activation of Al2(SO4)3·xH2O and the chemical and kinetic mechanisms of the desulphurization process. 相似文献
12.
W. Xinmin Q. Chuansong Q. Songsheng T. Zhicheng 《Journal of Thermal Analysis and Calorimetry》2007,90(2):569-573
Rare-earth perchlorate complex coordinated with glycine [Nd2(Gly)6(H2O)4](ClO4)6·5H2O was synthesized and its structure was characterized by using thermogravimetric analysis (TG), differential thermal analysis
(DTA), chemical analysis and elementary analysis. Its purity was 99.90%. Heat capacity measurement was carried out with a
high-precision fully-automatic adiabatic calorimeter over the temperature range from 78 to 369 K. A solid-solid phase transformation
peak was observed at 256.97 K, with the enthalpy and entropy of the phase transformation process are 4.438 kJ mol−1 and 17.270 J K−1 mol−1, respectively. There is a big dehydrated peak appears at 330 K, its decomposition temperature, decomposition enthalpy and
entropy are 320.606 K, 41.364 kJ mol−1 and 129.018 J K−1 mol−1, respectively. The polynomial equations of heat capacity of this compound in different temperature ranges have been fitted.
The standard enthalpy of formation was determined to be −8023.002 kJ mol−1 with isoperibol reaction calorimeter at 298.15 K. 相似文献
13.
Xin Jin Zhen Wang San-Ping Chen Zhu-Jun Wang Sheng-Li Gao 《Journal of Thermal Analysis and Calorimetry》2012,107(2):813-822
Two crystal samples, sodium 5-methylisophthalic acid monohydrate (C9H6O4Na2·H2O, s) and sodium isophthalic acid hemihydrate (C8H4O4Na2·1/2H2O, s), were prepared from water solution. Low-temperature heat capacities of the solid samples for sodium 5-methylisophthalic
acid monohydrate (C9H6O4Na2·H2O, s) and sodium isophthalic acid hemihydrate (C8H4O4Na2·1/2H2O, s) were measured by a precision automated adiabatic calorimeter over the temperature range from 78 to 379 K. The experimental
values of the molar heat capacities in the measured temperature region were fitted to a polynomial equation on molar heat
capacities (C
p,m) with the reduced temperatures (X), [X = f(T)], by a least-squares method. Thermodynamic functions of the compounds (C9H6O4Na2·H2O, s) and (C8H4O4Na2·1/2H2O, s) were calculated based on the fitted polynomial equation. The constant-volume energies of combustion of the compounds
at T = 298.15 K were measured by a precise rotating-bomb combustion calorimeter to be Δc
U(C9H6O4Na2·H2O, s) = −15428.49 ± 4.86 J g−1 and Δc
U(C8H4O4Na2·1/2H2O, s) = −13484.25 ± 5.56 J g−1. The standard molar enthalpies of formation of the compounds were calculated to be Δ
f
H
m
θ
(C9H6O4Na2·H2O, s) = −1458.740 ± 1.668 kJ mol−1 and Δ
f
H
m
θ
(C8H4O4Na2·1/2H2O, s) = −2078.392 ± 1.605 kJ mol−1 in accordance with Hess’ law. The standard molar enthalpies of solution of the compounds, Δ
sol
H
m
θ
(C9H6O4Na2·H2O, s) and Δ
sol
H
m
θ
(C8H4O4Na2·1/2H2O, s), have been determined as being −11.917 ± 0.055 and −29.078 ± 0.069 kJ mol−1 by an RD496-2000 type microcalorimeter. In addition, the standard molar enthalpies of hydrated anion of the compounds were
determined as being Δ
f
H
m
θ
(C9H6O4
2−, aq) = −704.227 ± 1.674 kJ mol−1 and Δ
f
H
m
θ
(C8H4O4Na2
2−, aq) = −1483.955 ± 1.612 kJ mol−1, from the standard molar enthalpies of solution and other auxiliary thermodynamic data through a thermochemical cycle. 相似文献
14.
Thermodynamic stability of CdMoO4 was determined
by measuring the vapor pressures of Cd and MoO3 bearing
gaseous species. Th vaporization reaction could be described as CdMoO4(s)+MoO2(s)
=Cd(g)+2/n(MoO3)n
(n=3, 4 and 5). The vapor pressures of
the cadmium (p
Cd)
and trimer (p
(MoO3)3)
measured in the temperature range 987≤T/K≤1111
could be expressed, respectively, as ln (p
Cd/Pa)
= –32643.9/T+29.46±0.08 and
ln(p
(MoO3)3/Pa) = –32289.6/T+29.28±0.08. The standard molar Gibbs free
energy of formation of CdMoO4(s),
derived from the vaporization results could be expressed by the equations:
°f
G
CdMoO4
(s)
0= –1002.0+0.267T±14.5 kJ mol–1
(987≤T/K≤1033) and °f
G
CdMoO4 (s)
0
= –1101.9+0.363T±14.4 kJ mol–1
(1044≤T/K≤1111). The standard enthalpy
of formation of CdMoO4(s)
was found to be –1015.4±14.5 kJ mol–1
. 相似文献
15.
Joanna Wiśniewska 《Transition Metal Chemistry》2007,32(6):811-815
The kinetics of the electron-transfer reactions between promazine (ptz) and [Co(en)2(H2O)2]3+ in CF3SO3H solution ([CoIII] = (2–6) × 10−3
m, [ptz] = 2.5 × 10−4
m, [H+] = 0.02 − 0.05 m, I = 0.1 m (H+, K+, CF3SO
3
−
), T = 288–308 K) and [Co(edta)]− in aqueous HCl ([CoIII] = (1 − 4) × 10−3
m, [ptz] = 1 × 10−4
m, [H+] = 0.1 − 0.5 m, I = 1.0 m (H+, Na+, Cl−), T = 313 − 333 K) were studied under the condition of excess CoIII using u.v.–vis. spectroscopy. The reactions produce a CoII species and a stable cationic radical. A linear dependence of the pseudo-first-order rate constant (k
obs) on [CoIII] with a non-zero intercept was established for both redox processes. The rate of reaction with the [Co(en)2(H2O)2]3+ ion was found to be independent of [H+]. In the case of the [Co(edta)]− ion, the k
obs dependence on [H+] was linear and the increasing [H+] accelerates the rate of the outer-sphere electron-transfer reaction. The activation parameters were calculated as follows:
ΔH
≠ = 105 ± 4 kJ mol−1, ΔS
≠ = 93 ± 11 J K−1mol−1 for [Co(en)2(H2O)2]3+; ΔH
≠ = 67 ± 9 kJ mol−1, ΔS
≠ = − 54 ± 28 J K−1mol−1 for [Co(edta)]−. 相似文献
16.
J. Straszko M. Olszak-Humienik J. Możejko 《Journal of Thermal Analysis and Calorimetry》1997,48(6):1415-1422
The thermal decomposition of iron sulphate hexahydrate was studied by thermogravimetry at a heating rate of 5°C min?1 in static air. The kinetic parameters were evaluated using the integral method by applying the Coats and Redfern approximation. The thermal stabilities of the hydrates were found to vary in the order. Fe2(SO4)3·6H2O → Fe2(SO4)3·4.5H2O → Fe2(SO4)3·0.5H2O The dehydration process of hydrated iron sulphate was found to conform to random nucleation mass loss kinetics, and the activation energies of the respective hydrates were 89.82, 105.04 and 172.62 kJ mol?1, respectively. The decomposition process of anhydrous iron sulphate occurs in the temperature region between 810 and 960 K with activation energies 526.52 kJ mol?1 for the D3 model or 256.05 kJ mol?1 for the R3 model. 相似文献
17.
L. Qiang-Guo H. Yi L. Xu Y. Li-Juan X. Sheng-Xiong Y. De-Jun L. Yi 《Journal of Thermal Analysis and Calorimetry》2008,91(2):615-620
The complex from reaction of neodymium chloride six-hydrate with salicylic acid and 8-hydroxyquinoline, Nd(C7H5O3)2·(C9H6NO), was synthesized and characterized by IR, elemental analysis, molar conductance, and thermogravimatric analysis. The standard
molar enthalpies of solution of [NdCl3·6H2O(s)], [2C7H6O3(s)], [C9H7NO(s)] and [Nd(C7H5O3)2·(C9H6NO)(s)] in a mixed solvent of anhydrous ethanol, dimethyl formamide (DMF) and perchloric acid were determined by calorimetry at
298.15 K. Based on Hess’ law, a new chemical cycle was designed, and the enthalpy change of the reaction
was determined to be Δr
H
mΘ=117.89±0.37 kJ mol−1. From data in the literature, through Hess’ law, the standard molar enthalpy of formation of Nd(C7H5O3)2·(C9H7NO)(s) was estimated to be Δf
H
mΘ[Nd(C7H5O3)2·(C9H6NO)(s), 298.15 K]=−2031.80±8.6 kJ mol−1.
Project supported by the Natural Sciences Foundation of Hunan Provincial of China (No. 03JJY3019) 相似文献
((1)) |
18.
The reaction of the · OH radical with the oxalate ion in an acidic aqueous solution was studied by pulse radiolysis. The rate
constant for the reaction of formation of the radical HOOC-COO·(λmax = 250 nm, ɛ = 1800 L mol−1 cm−1) is (5.0±0.5)·107 L mol−1 s−1. In the reaction with the hydrogen ion (k = 1.1·107 L mol−1 s−1), the radical HOOC-COO· is transformed into a nonidentified radical designated arbitrarily as H+(HOOC-COO)· (λmax = 260 nm, ɛ = 4000 L mol−1 cm−1).
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1165–1167, June, 2008. 相似文献
19.
2CaO·3B2O3·H2O which has non-linear optical (NLO) property was synthesized under hydrothermal condition and identified by XRD, FTIR and
TG as well as by chemical analysis. The molar enthalpy of solution of 2CaO·3B2O3·H2O in HCl·54.572H2O was determined. From a combination of this result with measured enthalpies of solution of H3BO3 in HCl·54.501H2O and of CaO in (HCl+H3BO3) solution, together with the standard molar enthalpies of formation of CaO(s), H3BO3(s), and H2O(l), the standard molar enthalpy of formation of −(5733.7±5.2) kJ mol−1 of 2CaO·3B2O3·H2O was obtained. Thermodynamic properties of this compound were also calculated by a group contribution method. 相似文献
20.
Gergely Kovács ákos Bencsura Sándor Dóbé Tibor Bérces Ferenc Márta 《Reaction Kinetics and Catalysis Letters》2005,86(2):355-361
Summary Pulsed laser photolysis coupled with time-resolved UV-absorption monitoring of CH3CO•radicals was applied to obtain the rate constant, k1, for the reaction CH3CO•+ HBr → CH3C(O)H + Br (1); k1(298 K) = (3.59 ± 0.23 (2σ))x10-12cm3molecule-1s-1. Utilization of k1in a third law procedure has provided the standard enthalpy of formation value ofDfH°298(CH3CO•) = -10.04 ± 1.10 (2σ) kJ mol-1in excellent agreement with a very recent IUPAC recommendation. 相似文献