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1.
J. N. Zhang Z. C. Tan Q. F. Meng Q. Shi B. Tong S. X. Wang 《Journal of Thermal Analysis and Calorimetry》2009,95(2):461-467
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 (Δfus
H
m0), and the molar entropy (Δfus
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, ΔU
c(C6H8N2,cr)= −3500.15±1.51 kJ mol−1 and Δc
H
m0 (C6H8N2,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, Δr
H
m0 (C6H8N2,cr)= −1.74±0.57 kJ mol−1. 相似文献
2.
The standard molar enthalpy of formation Δf
H
m
0=–760±12 kJ for amorphous silicon nitride a-Si3N4 has been determined from fluorine combustion calorimetry measurements of the massic energy of the reaction: a-Si3N4(s)+6F2(g)=3SiF4(g)+2N2(g). This value combined with Δf
H
m
0= –828.9±3.4 kJ for a-Si3N4 indicates that determined for the first time molar enthalpy change for the transition from amorphous to α-crystalline form
Δtrs
H
m
0=69±13 kJ is very evident, in spite of its large uncertainty range resulting from impurity corrections.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
3.
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
4.
M. A. V. Ribeiro da Silva Cláudia P. F. Santos 《Journal of Thermal Analysis and Calorimetry》2007,87(1):21-25
The standard (p
0=0.1
MPa) molar enthalpy of formation, Δf
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, Δg
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
5.
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
6.
The temperature dependence of the molar heat capacities of the tellurites
PbTeO3, Pb2Te3O8
and Ge(TeO3)2 are determined.
By statistical manipulation of the values obtained, the parameters in the
equations for the corresponding compounds showing this dependence are determined
using the least-squares method. These equations and the standard molar entropies
are used to determine the thermodynamic functions Δ0
T
S
m
0
, ΔT
T
H
m
0 and (Φm
0+Δ0
T
H
m
0/T) for T'=298.15
K. 相似文献
7.
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
8.
DTA and DSC were used to study the thermal behaviour of Ca(NO3)2·4H2O, Cd(NO3)2·4H2O, Mg(NO3)2·6H2O and their deuterated analogues. Evidence was found concerning the process of melting of the initial hydrates and deuterates,
followed by a one-stage dehydration of the melt to vield the respective anhydrous salt.
T
m, ΔH
m
o
, ΔS
m
o
and ΔH
deh
o
were determined and the ΔH
f
o
values for the investigated hydrates were calculated from the ΔH
deh
o
data.
Zusammenfassung DTA und DSC wurden zur Untersuchung des thermischen Verhaltens von Ca(NO3)2·4H2O, Cd(NO3)2·4H2O, Mg(NO3)2·6H2O und ihrer deuterierten Analoge eingesetzt. Man fand Aussagen bezüglich des Schmelzvorganges der Ausgangshydrate und Deuterate, gefolgt von einer Einschritt-Dehydratation der Schmelze unter Bildung der entsprechenden wasserfreien Salze. T m, ΔH m o , ΔS m o und ΔH deh o wurden ermittelt und die ΔH f o Werte für die untersuchten Hydrate wurden anhand der ΔH deh o berechnet.相似文献
9.
The temperature dependencies of the molar heat capacities of ZnTeO3, Zn2Te3O8, CdTeO3 and CdTe2O5 are determined. The experimental data are statistically processed using the least squares method to determine the parameters
in the equations for the corresponding compounds: Cp,m=a+b(T/K)-c(T/K)-2. These equations and the standard molar entropies are used to determine ΔT0S0m, ΔTTH0m and (Φ0m+ΔT,0H0m/T) for T'=298.15 K. 相似文献
10.
New divalent transition metal 3,5-pyrazoledicarboxylate
hydrates of empirical formula Mpz(COO)2(H2O)2,
where M=Mn, Co, Ni, Cu, Zn and Cd (pz(COO)2=3,5-pyrazoledicarboxylate),
metal hydrazine complexes of the type Mpz(COO)2N2H4
where M=Co, Zn or Cd and Mpz(COO)2nN2H4·H2O,
where n=1 for M=Ni
and n=0.5 for M=Cu
have been prepared and characterized by physico-chemical methods. Electronic
spectroscopic data suggest that Co and Ni complexes adopt an octahedral geometry.
The IR spectra confirm the presence of unidentate carboxylate anion (Δν=νasy(COO–)–νsym(COO–)>215
cm–1) in all the complexes and bidentate
bridging hydrazine (νN–N=985–950 cm–1)
in the metal hydrazine complexes. Both metal carboxylate and metal hydrazine
carboxylate complexes undergo endothermic dehydration and/or dehydrazination
followed by exothermic decomposition of organic moiety to give the respective
metal oxides as the end products except manganese pyrazoledicarboxylate hydrate,
which leaves manganese carbonate. X-ray powder diffraction patterns reveal
that the metal carboxylate hydrates are isomorphous as are those of metal
hydrazine complexes of cobalt, zinc and cadmium. 相似文献
11.
Lebedev B. V. Kulagina T. G. Smirnova N. N. Shifrina Z. B. Averina M. S. Rusanov A. L. 《Journal of Thermal Analysis and Calorimetry》2003,74(3):735-748
In an adiabatic vacuum calorimeter, the temperature dependence of the heat capacity C
p of phenylated polyphenylene and initial comonomer 1,4-bis(2,4,5-triphenylcyclopentadienone-3-yl)benzene was studied between
6 and 340 K with an uncertainty of about 0.2%. In a calorimeter with a static bomb and an isothermal shield their energies
of combustion DUcomb were measured. From the experimental data, the thermodynamic functions C
p
0 (T), H
0(T)-H
0(0), S
0(T)-S0(0), G
0(T)-H
0(0) were calculated from 0 to 340 K, and standard enthalpies of combustion ΔH
comb
0 and thermodynamic parameters of formation-enthalpies ΔH
f
0, entropies ΔH
f
0, Gibbs functions ΔG
f
0 - of the substances studied were estimated at T=298.15 K at standard pressure. The results were used to calculate the thermodynamic characteristics (ΔH
f
0 ,ΔS
f
0, ΔG
f
0) of phenylated polyphenylene synthesis in the range from 0 to 340 K.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
12.
B. Tong Z. C. Tan J. N. Zhang S. X. Wang 《Journal of Thermal Analysis and Calorimetry》2009,95(2):469-475
The low-temperature heat capacity C
p,m of erythritol (C4H10O4, CAS 149-32-6) was precisely measured in the temperature range from 80 to 410 K by means of a small sample automated adiabatic
calorimeter. A solid-liquid phase transition was found at T=390.254 K from the experimental C
p-T curve. The molar enthalpy and entropy of this transition were determined to be 37.92±0.19 kJ mol−1 and 97.17±0.49 J K−1 mol−1, respectively. The thermodynamic functions [H
T-H
298.15] and [S
T-S
298.15], were derived from the heat capacity data in the temperature range of 80 to 410 K with an interval of 5 K. The standard
molar enthalpy of combustion and the standard molar enthalpy of formation of the compound have been determined: Δc
H
m0(C4H10O4, cr)= −2102.90±1.56 kJ mol−1 and Δf
H
m0(C4H10O4, cr)= − 900.29±0.84 kJ mol−1, by means of a precision oxygen-bomb combustion calorimeter at T=298.15 K. DSC and TG measurements were performed to study the thermostability of the compound. The results were in agreement
with those obtained from heat capacity measurements. 相似文献
13.
A. Coetzee M. E. Brown D. J. Eve C. A. Strydom 《Journal of Thermal Analysis and Calorimetry》1994,41(2-3):357-385
Both isothermal and programmed temperature experiments have been used to obtain kinetic parameters for the dehydrations and
the decompositions in nitrogen of the mixed metal oxalates: FeCu(ox)2·3H2O, CoCu(ox)2·3H2O and NiCu(ox)2·3.5H2O, [ox=C2O4]. Results are compared with those reported for the thermal decompositions of the individual metal oxalates, Cuox, Coox·2H2O, Niox·2H2O and Feox·2H2O. X-ray photoelectron spectroscopy (XPS) was also used to examinee the individual and the mixed oxalates.
Dehydrations of the mixed oxalates were mainly deceleratory processes with activation energies (80 to 90 kJ·mol−1), similar to those reported for the individual hydrated oxalates. Temperature ranges for dehydration were broadly similar
for all the hydrates studied here (130 to 180°C).
Decompositions of the mixed oxalates were all complex endothermic processes with no obvious resemblance to the exothermic
reaction of Cuox, or the reactions of physical mixtures of the corresponding individual oxalates.
The order of decreasing stability, as indicated by the temperature ranges giving comparable decomposition rates, was NiCu(ox)2>CoCu(ox)2>FeCu(ox)2, which also corresponds to the order of increasing covalency of the Cu−O bonds as shown by XPS.
In celebration of the 60th birthday of Dr. Andrew K. Galwey 相似文献
14.
The temperature dependence of the molar heat capacities of the tellurites Fe2(TeO3)3, Fe2TeO5 and Fe2Te4O11 were determined. By statistical manipulation of the values obtained, the parameters in the equations for the corresponding
compounds showing this dependence were determined using the least-squares method. These equations together with the standard
molar entropies were used to determine the thermodynamic functions Δ0T
S
m0, ΔTT,H
m0 and (Φm0 + Δ0T’
H
m0 / T) for T’=298.15 K. 相似文献
15.
Yu H. G. Yu Dong J. X. Qin C. Q. Liu Y. Qu S. S. 《Journal of Thermal Analysis and Calorimetry》2004,75(3):807-813
The energy of combustion of crystalline 3,4,5-trimethoxybenzoic acid in oxygen at T=298.15 K was determined to be -4795.9±1.3 kJ mol-1 using combustion calorimetry. The derived standard molar enthalpies of formation of 3,4,5-trimethoxybenzoic acid in crystalline
and gaseous states at T=298.15 K, ΔfHm
Θ (cr) and ΔfHm
Θ (g), were -852.9±1.9 and -721.7±2.0 kJ mol-1, respectively. The reliability of the results obtained was commented upon and compared with literature values.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
16.
M. A. V. Ribeiro da Silva C. P. F. Santos M. J. S. Monte C. A. D. Sousa 《Journal of Thermal Analysis and Calorimetry》2006,83(3):533-539
The
standard (p0=0.1
MPa) molar enthalpies of formation, ΔfHm0, 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, ΔcrgHm0, 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
17.
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
18.
Summary The third-law method has been applied to determine the enthalpies, ΔrHT0, for dehydration reactions of kaolinite, muscovite and talc. The ΔrHT0values measured in the equimolar (in high vacuum) and isobaric (in the presence of water vapour) modes (980±15, 3710±39 and
2793±34 kJ mol-1, for kaolinite, muscovite and talc, respectively) practically coincide if to take into account the strong self-cooling effect
in vacuum. This fact strongly supports the mechanism of dissociative evaporation of these compounds in accordance with the
reactions (primary stages): Al2O3·2SiO2·2H2O(s)→Al2O3(g)↓+2SiO2(g)↓+2H2O(g); K2O·3Al2O3·6SiO2·2H2O(s) →K2O(g)↓+3Al2O3(g)↓+6SiO2(g)↓+2H2O(g) and 3MgO·4SiO2·H2O(s) →3MgO(g)↓+4SiO2(g)↓+H2O(g). The values of the Eparameter deduced from these data for equimolar and isobaric modes of dehydration are as follows: 196 and 327 kJ mol-1for kaolinite, 309 and 371 kJ mol-1for muscovite and 349 and 399 kJ mol-1for talc. These values are in agreement with quite a few early results reported in the literature in 1960s. 相似文献
19.
I. Zięborak-Tomaszkiewicz 《Journal of Thermal Analysis and Calorimetry》2006,83(3):611-615
The energies of combustion
in fluorine of gallium nitride and indium nitride in wurzite crystalline structure
have been measured in a two-compartment calorimetric bomb, and new standard
molar enthalpies of formation have been calculated: ΔfHm0(GaN(cr)
298.15 K)= –(163.7±4.2) kJ mol–1
and ΔfHm0(InN(cr) 298.15 K)= –(146.5±4.6) kJ mol–1
. Comparison with the recommended values of the ΔfHm0 nitrides
from the literature is also presented. 相似文献
20.
Lebedev B. V. Bykova T. A. Lobach A. S. 《Journal of Thermal Analysis and Calorimetry》2000,62(1):257-265
The temperature dependence of the molar heat capacity (C0
p) of hydrofullerene C60H36 between 5 and 340 K was determined by adiabatic vacuum calorimetry with an error of about 0.2%. The experimental data were
used for the calculation of the thermodynamic functions of the compound in the range 0 to340 K. It was found that at T=298.15 K and p=101.325 kPa C0
p (298.15)=690.0 J K−1 mol−1,Ho(298.15)−Ho(0)= 84.94 kJ mol−1,So(298.15)=506.8 J K−1 mol−1, Go(298.15)−Ho(0)= −66.17 kJ mol−1. The standard entropy of formation of hydrofullerene C60H36 and the entropy of reaction of its formation by hydrogenation of fullerene C60 with hydrogen were estimated and at T=298.15 K they were ΔfSo= −2188.4 J K−1 mol−1 and ΔrSo= −2270.5 J K−1mol−1, respectively.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献