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1.
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·H 2O)
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, Δ rHmθ (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, Δ rHmθ( 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, Δ cU, 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, Δ cHmθ, and standard enthalpy of formation,
Δ fHmθ, were calculated to be –16803.95±7.74 and –1115.42±8.94
kJ mol –1, respectively. 相似文献
2.
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
3.
The
heat capacities of 2-benzoylpyridine were measured with an automated adiabatic
calorimeter over the temperature range from 80 to 340 K. The melting point,
molar enthalpy, Δ fusHm,
and entropy, Δ fusSm,
of fusion of this compound were determined to be 316.49±0.04 K, 20.91±0.03
kJ mol –1 and 66.07±0.05 J mol –1
K –1, respectively. The purity of the compound
was calculated to be 99.60 mol% by using the fractional melting technique.
The thermodynamic functions ( HT– H298.15) and ( ST– S298.15) were calculated based
on the heat capacity measurements in the temperature range of 80–340
K with an interval of 5 K. The thermal properties of the compound were further
investigated by differential scanning calorimetry (DSC). From the DSC curve,
the temperature corresponding to the maximum evaporation rate, the molar enthalpy
and entropy of evaporation were determined to be 556.3±0.1 K, 51.3±0.2
kJ mol –1 and 92.2±0.4 J K –1
mol –1, respectively, under the experimental
conditions. 相似文献
4.
The standard molar enthalpy of combustion of cholesterol was measured at constant volume. According to value of Δ r
U
mθ(−14358.4±20.65 kJ mol −1), Δ r
H
mθ(−14385.7 kJ mol −1) of combustion reaction and Δ f
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
5.
The combustion energy of thioproline was determined
by the precision rotating-bomb calorimeter at 298.15 K to be Δ c
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 Δ c
H
m
θC 4H 7NO 2S,
(s), 298.15 K= –2469.92±1.44 kJ mol –1
and Δ f
H
m
θC 4H 7NO 2S, (s), 298.15K= –401.33±1.54
kJ mol –1. 相似文献
6.
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,
Δ c
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, Δ c
H
m
θ, and the standard molar of formation of the complex, Δ f
H
m
θ, were calculated as −12558.24±6.44 and −842.50±6.47 kJ mol −1, respectively. 相似文献
7.
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
8.
Low-temperature heat capacities of a solid
complex Zn(Val)SO 4·H 2O( 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 [ZnSO 4·7H 2O( s)+Val( s)] (Δ sol
H
m,l
0)
and the Zn(Val)SO 4·H 2O( s) (Δ sol
H
m,2
0) in 100.00 mL of 2 mol dm –3 HCl( aq) at T=298.15
K were determined to be, Δ sol
H
m,l
0=(94.588±0.025) kJ mol –1 and Δ sol
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: Δ f
H
m
0
(Zn(Val)SO 4·H 2O( 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 [ZnSO 4·7H 2O( s)+Val( s)] mixture
in 2 mol dm –3 hydrochloric acid) and solution
A’ (from dissolution of the complex Zn(Val)SO 4·H 2O( s) in 2 mol dm –3
hydrochloric acid). 相似文献
9.
The constant-volume combustion energies of
the lead salts of 2-hydroxy-3,5-dinitropyridine (2HDNPPb) and 4-hydroxy-3,5-dinitropyridine
(4HDNPPb), Δ U
c
(2HDNPPb( s) and 4HDNPP( s)),
were determined as –4441.92±2.43 and –4515.74±1.92
kJ mol –1 , respectively, at 298.15 K. Their
standard enthalpies of combustion, Δ c
m
H θ(2HDNPPb( s) and 4HDNPPb( s), 298.15 K), and standard enthalpies of formation,
Δ r
m H θ(2HDNPPb( s) and 4HDNPPb( s),
298.15 K) were as –4425.81±2.43, –4499.63±1.92 kJ
mol –1 and –870.43±2.76, –796.65±2.32
kJ mol –1 , respectively. As two combustion
catalysts, 2HDNPPb and 4HDNPPb can enhance the burning rate and reduce the
pressure exponent of RDX–CMDB propellant. 相似文献
10.
The heat capacities ( C
p,m) of 2-amino-5-methylpyridine (AMP) were measured by a precision automated adiabatic calorimeter over the temperature range
from 80 to 398 K. A solid-liquid phase transition was found in the range from 336 to 351 K with the peak heat capacity at
350.426 K. The melting temperature ( T
m), the molar enthalpy (Δ fus
H
m0), and the molar entropy (Δ fus
S
m0) of fusion were determined to be 350.431±0.018 K, 18.108 kJ mol −1 and 51.676 J K −1 mol −1, respectively. The mole fraction purity of the sample used was determined to be 0.99734 through the Van’t Hoff equation.
The thermodynamic functions ( H
T- H
298.15 and S
T- S
298.15) were calculated. The molar energy of combustion and the standard molar enthalpy of combustion were determined, Δ U
c(C 6H 8N 2,cr)= −3500.15±1.51 kJ mol −1 and Δ c
H
m0 (C 6H 8N 2,cr)= −3502.64±1.51 kJ mol −1, by means of a precision oxygen-bomb combustion calorimeter at T=298.15 K. The standard molar enthalpy of formation of the crystalline compound was derived, Δ r
H
m0 (C 6H 8N 2,cr)= −1.74±0.57 kJ mol −1. 相似文献
11.
The kinetics of the electron-transfer reactions between promazine (ptz) and [Co(en) 2(H 2O) 2] 3+ in CF 3SO 3H solution ([Co III] = (2–6) × 10 −3
m, [ptz] = 2.5 × 10 −4
m, [H +] = 0.02 − 0.05 m, I = 0.1 m (H +, K +, CF 3SO
3
−
), T = 288–308 K) and [Co(edta)] − in aqueous HCl ([Co III] = (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 Co III using u.v.–vis. spectroscopy. The reactions produce a Co II species and a stable cationic radical. A linear dependence of the pseudo-first-order rate constant ( k
obs) on [Co III] with a non-zero intercept was established for both redox processes. The rate of reaction with the [Co(en) 2(H 2O) 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:
Δ H
≠ = 105 ± 4 kJ mol −1, Δ S
≠ = 93 ± 11 J K −1mol −1 for [Co(en) 2(H 2O) 2] 3+; Δ H
≠ = 67 ± 9 kJ mol −1, Δ S
≠ = − 54 ± 28 J K −1mol −1 for [Co(edta)] −. 相似文献
12.
1. Results of thermodynamic and kinetic investigations for the different crystalline calcium carbonate phases and their phase
transition data are reported and summarized (vaterite: V; aragonite: A; calcite: C). A→C: T
tr=455±10°C, Δ tr
H=403±8 J mol –1 at T
tr, V→C: T
tr=320–460°C, depending on the way of preparation,Δ tr
H=–3.2±0.1 kJ mol –1 at T
tr,Δ tr
H=–3.4±0.9 kJ mol –1 at 40°C, S
V
Θ= 93.6±0.5 J (K mol) –1, A→C: E
A=370±10 kJ mol –1; XRD only, V→C: E
A=250±10 kJ mol –1; thermally activated, iso- and non-isothermal, XRD
2. Preliminary results on the preparation and investigation of inhibitor-free non-crystalline calcium carbonate (NCC) are
presented. NCC→C: T
tr=276±10°C,Δ tr
H=–15.0±3 kJ mol –1 at T
tr, T
tr – transition temperature, Δ tr
H – transition enthalpy, S
Θ – standard entropy, E
A – activation energy.
3. Biologically formed internal shell of Sepia officinalis seems to be composed of ca 96% aragonite and 4% non-crystalline calcium carbonate.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
13.
Three thermal effects on heating/cooling of K 2TaF 7 in the temperature interval of 680–800°C were investigated by the DSC method. The values determined for the enthalpy change
of the individual processes are: Δ transIIH m(K 2TaF 7; 703°C) = 1.7(2) kJ mol −1, Δ transIH m(K 2TaF 7; 746°C) = 19(1) kJ mol −1 and Δ transIIIH m(K 2TaF 7; 771°C) = 13(1) kJ mol −1. The first thermal effect was attributed to a solid-solid phase transition; the second to the incongruent melting of K 2TaF 7 and the third to mixing of two liquids. These findings are supported by in situ neutron powder diffraction experiments performed in the temperature interval of 654–794°C.
相似文献
14.
The kinetics of the oxidation of promazine by trisoxalatocobaltate(III) were studied in the presence of a large excess of
the cobalt(III) in tris buffer solution using u.v.–vis spectroscopy ([Co III] = (0.6 − 2) × 10 −3
M, [ptz] = 6 × 10 −5
M, pH = 6.6–7.8, I = 0.1 M (NaCl), T = 288−308 K, l = 1 cm). The reaction proceeds via two consecutive reversible steps. In the first step, the reaction leads to formation of cobalt(II) species and a stable cationic
radical. In the second step, cobalt(III) is reduced to cobalt(II) ion and a promazine radical is oxidized to the promazine
5-oxide. Linear dependences of the pseudo-first-order rate constants ( k
1 and k
2) on [Co III] with a non-zero intercept were established for both redox processes. Rates of reactions decreased with increasing concentration
of the H + ion indicating that the promazine and its radical exist in equilibrium with their deprotonated forms, which are reactive
reducing species. The activation parameters for reactions studied were as follows: ΔH ≠ = 44 ± 1 kJ mol −1, ΔS ≠ = −100 ± 4 JK −1 mol −1 for the first step and ΔH ≠ = 25 ± 1 kJ mol −1, ΔS ≠ = −169 ± 4 J K −1 mol −1 for the second step, respectively. Mechanistic consequences of all the results are discussed. 相似文献
15.
The temperature dependences of the equilibrium constants of two chain reversible reactions in quinonediimine (quinonemonoimine)—2,5-dichlorohydroquinone
systems in chlorobenzene were studied. The enthalpy of equilibrium of the reversible reaction of quinonediimine with 4-hydroxydiphenylamine
was estimated from these data (Δ H = − 14.4±1.6 kJ mol −1) and a more accurate value of the N-H bond dissociation energy in the 4-anilinodiphenylaminyl radical was determined ( D
NH = 278.6±3.0 kJ mol −1). A chain mechanism was proposed for the reaction between quinonediimine and 2,5-dichlorohydroquinone, and the chain length
was estimated (ν = 300 units) at room temperature. Processing of published data on the rate constant of the reaction of styrylperoxy
radicals with 2,5-dichlorohydroquinone in the framework of the intersecting parabolas method gave the O-H bond dissociation
energy in 2,5-dichlorohydroquinone: D
OH = 362.4±0.9 kJ mol −1. Taking into account these data, the O-H bond dissociation energy in the 2,5-dichlorosemiquinone radical was found: D
OH = 253.6±1.9 kJ mol −1.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1661–1666, October, 2006. 相似文献
16.
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 Δ f
H
m
θ[La(Ala) 3Cl 3·3H 2O( s), 298.2 K]= -3716.3 kJ mol -1, Δ f
H
m
θ [La(Gly) 3Cl 3·5H 2O( s), 298.2 K]= -4223.0 kJ mol -1 and Δ f
H
m
θ [La(Ala) 4(NO 3) 3·H 2O( 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
17.
Rare-earth perchlorate complex coordinated with glycine [Nd 2(Gly) 6(H 2O) 4](ClO 4) 6·5H 2O 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
18.
The
standard ( p0=0.1
MPa) molar enthalpies of formation, Δ fHm0, for
crystalline phthalimides: phthalimide, N-ethylphthalimide
and N-propylphthalimide were derived from
the standard molar enthalpies of combustion, in oxygen, at the temperature
298.15 K, measured by static bomb-combustion calorimetry, as, respectively,
– (318.0±1.7), – (350.1±2.7) and – (377.3±2.2)
kJ mol –1. The standard molar enthalpies of
sublimation, Δ crgHm0, at T=298.15
K were derived by the Clausius-Clapeyron equation, from the temperature dependence
of the vapour pressures for phthalimide, as (106.9±1.2) kJ mol –1
and from high temperature Calvet microcalorimetry for phthalimide, N-ethylphthalimide and N-propylphthalimide
as, respectively, (106.3±1.3), (91.0±1.2) and (98.2±1.4)
kJ mol –1.
The derived standard molar enthalpies of formation,
in the gaseous state, are analysed in terms of enthalpic increments and interpreted
in terms of molecular structure. 相似文献
19.
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
20.
Summary The kinetics of the acid-catalysed hydrolysis of the [(imidazole) 4Co(CO 3)] + ion was found to follow the rate law -dln[complex]/dt = k
1
K[H +](1 + K[H
+]) in the 25–45 °C range, [H +] 0.05–1.0 m range and I = 1.0 m. The reaction sequence consists of a rapid protonation equilibrium followed by the one-end dissociation of the coordinated
carbonato ligand (rate-determining step) and subsequent fast release of the monodentate carbonato ligand. The rate parameter
values, k
1 and ITK, at 25 °C are 6.48 × 10 −3s −1 and 0.31 m
−1, respectively, and activation parameters for k
1 are Δ H
1
≠ = 86.1 ± 1.2kJ mol −1 and Δ S
1
≠ = 2.1 ± 6.3 J mol −1K −1. The hydrolysis rate increases with increase in ionic strength. The different ways of dealing with the data fit are presented
and discussed. The kinetic results are compared with those for the similar cobalt(III) complexes. 相似文献
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