共查询到20条相似文献,搜索用时 33 毫秒
1.
The enthalpy change of formation of the reaction of hydrous dysprosium chloride with ammonium pyrrolidinedithiocarbamate (APDC) and 1,10-phenanthroline (o-phen•H2O) in absolute ethanol at 298.15 K has been determined as (-16.12 ± 0.05) kJ•mol-1 by a microcalormeter. Thermodynamic parameters (the activation enthalpy, the activation entropy and the activation free energy), rate constant and kinetics parameters (the apparent activation energy, the pre-exponential constant and the reaction order) of the reaction have also been calculated. The enthalpy change of the solid-phase reaction at 298.15 K has been obtained as (53.59 ± 0.29) kJ•molt-1 by a thermochemistry cycle. The values of the enthalpy change of formation both in liquid-phase and solid-phase reaction indicated that the complex could only be synthesized in liquid-phase reaction. 相似文献
2.
Summary A ternary solid complex Gd(Et 2dtc) 3(phen) has been obtained from reactions of sodium diethyldithiocarbamate (NaEt 2dtc), 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, Δ rHΘm( 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, Δ rHΘm( 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 (Δ rHΘ≠), the activation entropy (Δ rSΘ≠), the activation free energy (Δ rGΘ≠) and the enthalpy (Δ rHΘ≠), 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, Δ cU, 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, Δ cHΘm, and standard enthalpy of formation, Δ fHΘm, were calculated to be (-18692.92±8.15) kJ mol -1 and (-51.28±9.17) kJ mol -1, respectively. 相似文献
3.
The enthalpy change of formation of the reaction of hydrous dysprosium chloride with ammonium pyrrolidinedithiocarbamate (APDC) and 1,10-phenanthroline (o-phen·H2O) in absolute ethanol at 298.15 K has been determined as (-16.12±0.05) kJ·mol-1 by a microcalor-meter. Thermodynamic parameters (the activation enthalpy, the activation entropy and the activation free energy), rate constant and kinetics parameters (the apparent activation energy, the pre-exponential constant and the reaction order) of the reaction have also been calculated. The enthalpy change of the solid-phase reaction at 298.15 K has been obtained as (53.59±0.29) kJ·mol-1 by a thermochemistry cycle. The values of the enthalpy change of formation both in liquid-phase and solid-phase reaction indicated that the complex could only be synthesized in liquid-phase reaction. 相似文献
4.
Enthalpy of formation of the perovskite-related oxide BaCe 0.9In 0.1O 2.95 has been determined at 298.15 K by solution calorimetry. Solution enthalpies of barium cerate doped with indium and mixture
of BaCl 2, CeCl 3, InCl 3 in ratio 1:0.9:0.1 have been measured in 1 M HCl with 0.1 M KI. The standard formation enthalpy of BaCe 0.9In 0.1O 2.95 has been calculated as −1611.7±2.6 kJ mol −1. Room-temperature stability of this compound has been assessed in terms of parent binary oxides. The formation enthalpy of
barium cerate doped by indium from the mixture of binary oxides is Δ ox
H
0 (298.15 K)=−36.2±3.4 kJ mol −1. 相似文献
5.
The heat capacity and the enthalpy increments of strontium metaniobate SrNb 2O 6 were measured by the relaxation method (2-276 K), micro DSC calorimetry (260-320 K) and drop calorimetry (723-1472 K). Temperature
dependence of the molar heat capacity in the form C
pm=(200.47±5.51)+(0.02937±0.0760) T-(3.4728±0.3115)·10 6/ T
2 J K −1 mol −1 (298-1500 K) was derived by the least-squares method from the experimental data. Furthermore, the standard molar entropy
at 298.15 K S
m0 (298.15 K)=173.88±0.39 J K −1 mol −1 was evaluated from the low temperature heat capacity measurements. The standard enthalpy of formation Δ f
H
0 (298.15 K)=-2826.78 kJ mol −1 was derived from total energies obtained by full potential LAPW electronic structure calculations within density functional
theory. 相似文献
6.
Summary As part of a larger study of the physical properties of potential ceramic hosts for nuclear wastes, we report the molar heat capacity of brannerite (UTi 2O 6) and its cerium analog (CeTi 2O 6) from 10 to 400 K using an adiabatic calorimeter. At 298.15 K the standard molar heat capacities are (179.46±0.18) J K -1 mol -1 for UTi 2O 6 and (172.78±0.17) J K -1 mol -1 for CeTi 2O 6. Entropies were calculated from smooth fits of the experimental data and were found to be (175.56±0.35) J K -1 mol -1 and (171.63±0.34) J K -1 mol -1 for UTi 2O 6 and CeTi 2O 6, respectively. Using these entropies and enthalpy of formation data reported in the literature, Gibb’s free energies of formation from the elements and constituent oxides were calculated. Standard free energies of formation from the elements are (-2814.7±5.6) kJ mol -1 for UTi 2O 6 and (-2786.3±5.6) kJ mol -1 for CeTi 2O 6. The free energy of formation from the oxides at T=298.15 K are (-5.31±0.01) kJ mol -1 and (15.88±0.03) kJ mol -1 for UTi 2O 6 and CeTi 2O 6, respectively. 相似文献
7.
Summary The binary systems of C 60with α-methyl- and α-chloronaphthalene have been studied by means of differential scanning calorimetry. C 60was found to form the molecular complex of the van der Waals type with α-methylnaphthalene which melts incongruently below
the boiling point of the solvent at temperature 382.7±3.0 K. The enthalpy of the desolvation reaction is 14.1±0.5 kJ mol -1of C 60. The molar ratio of fullerene to solvent in the solvate is 1:1.5. In the system C 60-α-chloronaphthalene a two-stage incongruent melting process has been observed at temperatures 314.1±4.6 K and 375.7±7.4 K
with the enthalpies 8.1±2.6 kJ mol -1and 11.6±1.0 kJ mol -1, respectively. The composition of the most solvated phase equilibrated with the saturated solution at room temperature and
below the first of the incongruent melting transitions was determined as 1:1.5. Based on the results obtained the thermodynamic
characteristics of the incongruent melting reactions have been revealed and influence of solvate formation on solubility of
C 60has been discussed. 相似文献
8.
A thermochemical study of natural talc was performed by high-temperature melt dissolution calorimetry on a Tian-Calvet calorimeter.
Based on the total values of the increment in enthalpy upon heating the sample from room temperature to 973 K, and of the
dissolution enthalpy at 973 K measured in this work for talc and gibbsite (along with those determined for tremolite, brucite,
and their corresponding oxides), the enthalpy of formation was calculated for talc composed of elements, Mg 3[Si 4O 10](OH) 2, at 298.15 K: Δ f
H
elo(298.15 K) = −5900.6 ± 4.7 kJ/mol. 相似文献
9.
Summary The standard molar enthalpy of formation of methyl methylthiomethyl sulfoxide, CH 3(CH 3SCH 2)SO, at T=298.15 K in the liquid state was determined to be -199.4±1.5 kJ mol -1 by means of oxygen rotating-bomb combustion calorimetry. 相似文献
10.
Areas of fusion and crystallization peaks of K 3TaO 2F 4 and KTaF 6 were measured using the DSC mode of a high-temperature calorimeter (SETARAM 1800 K). On the basis of these quantities, considering
the temperature dependence of the calorimeter sensitivity, values of the fusion enthalpy of K 3TaO 2F 4 at the fusion temperature of 1181 K of (43 ± 4) kJ mol −1 and of KTaF 6 at the fusion temperature of 760 K of (8 ± 1) kJ mol −1 were determined. 相似文献
11.
A
solid complex Eu(C 5H 8NS 2) 3(C 12H 8N 2) has been obtained from reaction of
hydrous europium chloride with ammonium pyrrolidinedithiocarbamate (APDC)
and 1,10-phenanthroline ( o-phen⋅H 2O)
in absolute ethanol. IR spectrum of the complex indicated that Eu 3+
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, Δ r
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, Δ r
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 (Δ H
≠
θ),
the activation entropy (Δ S
≠
θ),
the activation free energy (Δ G
≠
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, Δ c
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, Δ c
H
m
θ,
and standard enthalpy of formation, Δ f
H
m
θ,
were calculated to be –16953.37±9.79 and –1708.23±10.69
kJ mol –1, respectively. 相似文献
12.
The molar enthalpies of solution of 2-aminopyridine at various molalities were measured at T=298.15 K in double-distilled water by means of an isoperibol solution-reaction calorimeter. According to Pitzer’s theory,
the molar enthalpy of solution of the title compound at infinite dilution was calculated to be D solHm¥ = 14.34 kJ·mol -1\Delta_{\mathrm{sol}}H_{\mathrm{m}}^{\infty} = 14.34~\mbox{kJ}\cdot\mbox{mol}^{-1}, and Pitzer’s ion interaction parameters b MX(0)L, b MX(1)L\beta_{\mathrm{MX}}^{(0)L}, \beta_{\mathrm{MX}}^{(1)L}, and CMXfLC_{\mathrm{MX}}^{\phi L} were obtained. Values of the relative apparent molar enthalpies (
φ
L) and relative partial molar enthalpies of the compound ([`( L)] 2)\bar{L}_{2}) were derived from the experimental enthalpies of solution of the compound. The standard molar enthalpy of formation of the
cation C 5H 7N 2 +\mathrm{C}_{5}\mathrm{H}_{7}\mathrm{N}_{2}^{ +} in aqueous solution was calculated to be D fHmo(C 5H 7N 2+,aq)=-(2.096±0.801) kJ·mol -1\Delta_{\mathrm{f}}H_{\mathrm{m}}^{\mathrm{o}}(\mathrm{C}_{5}\mathrm{H}_{7}\mathrm{N}_{2}^{+},\mbox{aq})=-(2.096\pm 0.801)~\mbox{kJ}\cdot\mbox{mol}^{-1}. 相似文献
13.
B3LYP method with the LANL2DZ basis for tin and aug-cc-pVDZ basis for carbon and hydrogen were used to obtain the equilibrium
geometry of the main (with a positive charge on the tin) isomers in the C 4H 11Sn + system and the transition states at their interconversion. As in the case of silicon and germanium, the cations of lighter
elements of the 14th group, the most stable isomer is shown to be the tertiary ion, however, the energy of its complexes with
ethane and propane is higher only by several kJ mol −1. Nevertheless, the formation of these complexes from the tertiary ion requires overcoming a rather high barrier (293 and
272 kJ mol −1, respectively). The barrier for isomerization of the secondary ion in the ethane complex is somewhat lower (222 kJ mol −1), but still is significantly greater than the energy gained at the appearance of the nucleogenic ion. The most probable transformation
pathways of the nucleogenic stannylium ions are the formation of complexes with ethylene, which requires overcoming barriers
of 130 and 117 kJ mol −1 for the tertiary and secondary ions, respectively. 相似文献
14.
Transport properties of ionic salt CsH 5(PO 4) 2 are studied by the impedance method. The salt’s bulk conductivity ranges from 10 ?8 to 10 ?4 S cm ?1 in the temperature interval 90 to 145°C. The apparent activation energy is high (1.6–2.0 eV). The conductivity is slightly anisotropic: it is maximum in the [001] direction and minimum in the [100] direction (~5.6 and 1 times × 10 ?6 S cm ?1, respectively, at 130°C). The conductivity of polycrystalline samples is higher by 1–2 orders of magnitude, and the activation energy drops to 1.05 eV due to the formation of a pseudoliquid layer with a high proton mobility at the intercrystallite boundary. The salt’s thermodynamic properties are examined by differential scanning calorimetry and thermogravimetry. No phase transitions are discovered in the salt up to the melting point (151.6°C), with the melting enthalpy equal to ~34 kJ mol ?1. The crystallization occurs at lower temperatures (107°C) and the crystallization enthalpy (?18 kJ mol ?1) is lower than the melting enthalpy. The melting is accompanied by slow decomposition of the salt. Factors affecting the proton transport in the salt are analyzed. 相似文献
15.
The standard ( p
0=0.1
MPa) molar enthalpy of formation, Δ f
H
0
m, for crystalline N-phenylphthalimide
was derived from its standard molar enthalpy of combustion, in oxygen, at
the temperature 298.15 K, measured by static bomb-combustion calorimetry,
as –206.0±3.4 kJ mol –1. The
standard molar enthalpy of sublimation, Δ g
cr
H
0
m
, at T=298.15 K, was derived, from high
temperature Calvet microcalorimetry, as 121.3±1.0 kJ mol –1.
The derived standard molar enthalpy of formation, in the gaseous state,
is analysed in terms of enthalpic increments and interpreted in terms of molecular
structure. 相似文献
16.
The standard enthalpies of formation of liquid and gaseous octachlorotrisilane were estimated, Δ f H o (298.15, Si 3Cl 8, g) = ?1397(9) kJ/mol and Δ f H o (298.15, Si 3Cl 8, l) = ?1447(9) kJ/mol. The decomposition of Si 3Cl 8 over the temperature range 400–1000 K was studied theoretically. 相似文献
17.
Areas of fusion and crystallization peaks of K 3NbO 2F 4 were measured using the DCS mode of a high-temperature calorimeter (SETARAM 1800 K). On the basis of these quantities, considering
the temperature dependence of the calorimeter sensitivity, the value of the fusion enthalpy of K 3NbO 2F 4 of (98 ± 6) kJ mol −1 was determined at the fusion temperature of 1257 K. 相似文献
18.
The novel ternary solid complex Gd(C 5H 8NS 2) 3(C 12H 8N 2) has been obtained from the reaction of hydrous gadolinium chloride, ammonium pyrrolidinedithiocarbamate (APDC), and 1,10-phenanthroline
( o-phen · H 2O) 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, Δ r
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, Δ r
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 (Δ H
≠
ϑ
), the activation entropy (Δ S
≠
ϑ
), the activation free energy (Δ G
≠
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, Δ c
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, Δ c
H
m
ϑ
, and standard enthalpy of formation, Δ f
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
19.
A mass spectrometric study of the saturated vapor over ytterbium tris(hexafluoroacetylacetonate) Yb(hfa) 3 (hfa = CF 3-C(O)-CH-C(O)-CF 3) 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 (Δ H
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: Δ H
dis(380 K) = 130 ± 15 kJ/mol. 相似文献
20.
Equilibrium constants for 2-methylpropan-1-ol + 2-methylpropanal + hydrogen have been calculated from measurements of the composition of mixtures formed by passing the vapour over a catalyst at several temperatures in the range 473 to 563 K. Equations relating the changes in enthalpy and entropy of the dehydrogenation reaction to temperature were derived from the equilibrium constants with the aid of heat capacities. By coupling these changes with other thermodynamic data, the standard enthalpy of formation and the standard entropy of 2-methylpropanal at 298.15 K were calculated to be ?(215.7 ± 1.3) kJ mol ?1 and (331.2 ± 1.7) J K ?1 mol ?1 respectively, in the gas state, and ?(247.3 ± 1.8) kJ mol ?1 and (238.3 ± 4.4) J K ?1 mol ?1 respectively, in the liquid state. 相似文献
|