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1.
F. Bousmina L. Zayani D. Ben Hassen-Chehimi N. Kbir-Ariguib M. Trabelsi-Ayedi 《Monatshefte für Chemie / Chemical Monthly》2003,4(10):763-768
The diagram of the ternary system Mg2+/Cl−, SO4 2−–H2O was established at 15°C by means of analytical and conductimetric measurements. Three compounds were found in this diagram, which are MgSO4·6H2O, MgSO4·7H2O, and MgCl2·6H2O. The solubility field of MgSO4·7H2O is important whereas those of MgSO4·6H2O and MgCl2·6H2O are small. The compositions (mass-%) of the two invariant points determined by the two methods are: MgSO4:MgCl2=2.73:33.80 and MgSO4: MgCl2=3.38:28.91. Both the measured and the calculated isotherm at 15°C have been used for modelling of the diagram Mg2+/Cl−, SO4 2−–H2O between 0 and 35°C. The polythermal invariant point was approximately located between 15 and 10°C. 相似文献
2.
Budrugeac P. Criado J. M. Gotor F. J. Popescu C. Segal E. 《Journal of Thermal Analysis and Calorimetry》2001,63(3):777-786
The heats of hydration reactions for MgCl2⋅4H2O and MgCl2⋅2H2O include two parts, reaction enthalpy and adsorption heat of aqueous vapor on the surfaces of magnesium chloride hydrates.
The hydration heat for the reactions MgCl2⋅4H2O+2H2O→MgCl2⋅6H2O and MgCl2⋅2H2O+2H2O→MgCl2⋅4H2O, measured by DSC-111, is –30.36 and –133.94 kJ mol–1,respectively. The adsorption heat of these hydration processes, measured by head-on chromatography method, is –13.06 and
–16.11 kJ mol–1, respectively. The molar enthalpy change for the above two reactions is –16.64 and –118.09 kJ mol–1, respectively. The comparison between the experimental data and the theoretical values for these hydration processes indicates
that the results obtained in this study are quite reliable.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
3.
F. Bousmina L. Zayani D. Ben Hassen-Chehimi N. Kbir-Ariguib M. Trabelsi-Ayedi 《Monatshefte für Chemie / Chemical Monthly》2003,134(5):763-768
Summary. The diagram of the ternary system Mg2+/Cl−, SO4
2−–H2O was established at 15°C by means of analytical and conductimetric measurements. Three compounds were found in this diagram,
which are MgSO4·6H2O, MgSO4·7H2O, and MgCl2·6H2O. The solubility field of MgSO4·7H2O is important whereas those of MgSO4·6H2O and MgCl2·6H2O are small. The compositions (mass-%) of the two invariant points determined by the two methods are: MgSO4:MgCl2=2.73:33.80 and MgSO4: MgCl2=3.38:28.91. Both the measured and the calculated isotherm at 15°C have been used for modelling of the diagram Mg2+/Cl−, SO4
2−–H2O between 0 and 35°C. The polythermal invariant point was approximately located between 15 and 10°C.
Corresponding author. E-mail: ariguib@planet.tn
Received October 16, 2002; accepted (revised) December 3, 2002
Published online April 24, 2003
RID="a"
ID="a" Dedicated to Prof. Dr. Heinz Gamsj?ger on the occasion of his 70th birthday 相似文献
4.
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
5.
E. V. Ivanov V. K. Abrosimov N. G. Ivanova E. Yu. Lebedeva 《Russian Chemical Bulletin》2007,56(10):1996-1999
The densities of aqueous solutions of bisurea (2,4,6,8-tetraazabicyclo[3.3.0]octane-3,7-dione) were measured using a vibrating-tube
densimeter at 288.15, 298.15, 308.15, and 318.15 K in the concentration range up to ∼3·10−3 moles of solute (1000 g of H2O)−1 with the error at most ±5· 10−6 g cm−3 (reproducibility up to 2·10−6 g cm−3). The limiting partial molar volume and expansibility of bisurea in water were calculated. The bicyclic molecules under study
form in aqueous solution H-bonded hydrate complexes with rather high structure-packing density. These complexes are more subjected
to the destroying effect of temperature than the corresponding urea complexes. The hydration of bisurea weakens with the temperature
increase.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1929–1932, October, 2007. 相似文献
6.
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
7.
A thermal method using differential scanning calorimeter has been applied to aqueous solutions of a series of poly(tetraalkylammonium ethenesulfonates) (R4NPES). It was found that only the salts withR=n-C4H9 andR=i-C5H11 could form stable hydrates having large hydration numbers. The melting point and hydration numbers of these two hydrates were 12.0°C and 30±1 for the (n-C4H9)4NPES hydrate and 16.0°C and 53±2 for the (i-C5H11)4NPES hydrate, respectively. It was concluded that these hydrates were clathrate-like essentially similar to such hydrates as (n-C4H9)4NF·30H2O and (i-C5H11)4NF·40H2O. 相似文献
8.
Zhanping Qiao Junlin Gao Lihong Zhuo Meili Zhang Shuai Zhang 《Russian Journal of Inorganic Chemistry》2009,54(9):1474-1478
The equilibrium solubility of the quaternary system RbCl-PrCl3-HCl-H2O was determined at 298.15 K and the corresponding equilibrium diagram was constructed in this paper. The quaternary system
is complicated with three equilibrium solid phases, RbCl, RbPrCl4 · 4H2O (1:1 type) and PrCl3 · 6H2O, of which the new compound RbPrCl4 · 4H2O was found to be congruently soluble in the system. The new compound obtained was identified and characterized by the methods
of X-ray diffraction, thermogravimetry, and differential thermogravimetry. The compound loses its crystal water by one step
at 343 K to 453 K. The standard molar enthalpy of solution of RbPrCl4 · 4H2O in deionized water was measured to be −24.53 ± 0.22 kJ mol−1 by heat conduction microcalorimetry. Its standard molar enthalpy of formation was calculated to be −2743.20 ± 1.09 kJ mol−1. 相似文献
9.
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
10.
11.
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
12.
N. K. Tunali H. N. Erten S. Kinikoğlu Ş. Gümüş 《Journal of Radioanalytical and Nuclear Chemistry》1979,49(2):225-237
The extraction of iodine and bromine under various conditions from their saturated aqueous solutions by CCl4, C6H6 and o-xylene has been studied. The data obtained from the experiments carried out at various temperatures, for H2O(I2)−CCl4 and H2O(I2)−C6H6 systems, exhibit an Arrhenius behaviour. The overall activation energy calculated for the extraction in the H2O(I2)−CCl4 system, 650±50 cal·mol−1 is lower than that of H2O(I2)−C6H6, 3600±300 cal·mol−1. The use of the solubility parameter for the interpretation of the data in the extraction of iodine is investigated. The
data obtained in multiple extractions are treated by using the analogy between extraction and radioactive decay. The half
number of extraction for each system is determined. The complex curves obtained in the H2O(I2)−CCl4 and H2O(I2) −Br2)−CCl4 systems are resolved into two components. 相似文献
13.
J. Monaselidze Maya Kiladze D. Tananashvili Shota Barbakadze A. Naskidashvili Anna Khizanishvili R. Kvavadze G. Majagaladze 《Journal of Thermal Analysis and Calorimetry》2006,84(3):613-618
The heat
effects arising at heating of Spirulina platensis
cell culture containing different quantity of water (from 98.2 to 10.5 mass%
H2O) have been studied. The hydration of Sp. pl. cells determined by the method of microcalorimetry
at 25°C (Δn) was equal to 0.32±0.02
g H2O/g of dry biomass. The heat (–Q) evolved by cells in the temperature range 5–52°C
decreased exponentially at decrease of mass% H2O and
reached zero value at 30.5±3.0 mass% H2O. The
total heat of cell denaturation did not change in the range 98.2–40.5
mass% H2O and it sharply dropped at lower values of
water. 相似文献
14.
Thermal phenomena at the hydration of calcium sulphate hemihydrate (CaSO4·0.5H2O) are investigated in the paper. Time development of hydration heat of β-calcium sulphate hemihydrate prepared from flue
gas desulphurization (FGD) gypsum is determined using two different types of calorimeter, namely the differential calorimeter
DIK 04 and the isothermal heat flow calorimeter KC 01, and the differences in measured data analyzed. Then, the effects of
plasticizers and hydrophobizers on the hydration process of analyzed gypsum mixtures are studied. 相似文献
15.
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
16.
T. V. Rodionova Yu. A. Dyadin K. A. Udachin Ya. Lipkowski K. Suwinska 《Journal of Structural Chemistry》1995,36(3):458-464
Phase diagrams of some binary aqueous systems with tetraalkylammonium fluorides are examined. The size of the hydrophobic
moiety of the guest is consecutively varied in the series (i-C5H11)4−k(C4H9)kNF (k=0, 1, 2, 3) by replacing bulky isoamyl radicals with n-butyl radicals. Changes in clathrate formation caused by variations
of the sizes and forms of guests are analyzed in the series (i-C5H11)k−4(C4H9)kNF−H2O (k=0, 1, 2, 3, 4). All tetraisoamylammonium fluoride hydrates are more stable than other hydrates of this series. The stability
of the compounds increases due to the fact that the isoamyl radicals use the host cavities more effectively than the butyl
radicals. In all hydrates of the series, tetragonal structures-I (TS-I), which were earlier thought typical only for hydrates
of tetrabutylammonium salts, are formed. Hydrates of the orthorhombic system are formed until three isoamyl radicals have
been replaced by butyl radicals. Hydrates with 26–28 water molecules (mp 27.4–34.6°C) are the most stable hydrates of the
series, except for i-AmBu3NF·25.9 H2O, melting 0.3°C lower than the tetragonal hydrate in the same system. All compounds are defined chemically, and for some
of them crystal data are given.
Institute of Inorganic Chemistry, Siberian Branch, Russian Academy of Sciences. Institute of Physical Chemistry, Polish Academy
of Sciences. Translated fromZhurnal Strukturnoi Khimii, Vol. 36, No. 3, pp. 501–508, May–June, 1995.
Translated by L. Smolina 相似文献
17.
Jonathan F. Ojo Jide Ige Grace O. Ogunlusi Olanrewaju Owoyomi Esan S. Olaseni 《Transition Metal Chemistry》2006,31(6):782-785
The kinetics of the reactions between Fe(phen)
3
2+
[phen = tris–(1,10) phenanthroline] and
Co(CN)5X3− (X = Cl, Br or I) have been investigated in aqueous acidic solutions at I = 0.1 mol dm−3 (NaCl/HCl). The reactions were carried out at a fixed acid concentration ([H+] = 0.01 mol dm−3) and the second-order rate constants for the reactions at 25 °C were within the range of (0.151–1.117) dm3 mol−1 s−1. Ion-pair constants K
ip for these reactions, taking into consideration the protonation of the cobalt complexes, were 5.19 × 104, 3.00 × 102 and 4.02 × 104 mol−1 dm−3 for X = Cl, Br and I, respectively. Activation parameters measured for these systems were as follows: ΔH* (kJ K−1 mol−1) = 94.3 ± 0.6, 97.3 ± 1.0 and 109.1 ± 0.4; ΔS* (J K−1) = 69.1 ± 1.9, 74.9 ± 3.2 and 112.3 ± 1.3; ΔG* (kJ) = 73.7 ± 0.6, 75.0 ± 1.0 and 75.7 ± 0.4; E
a
(kJ) = 96.9 ± 0.3, 99.8 ± 0.4, and 122.9 ± 0.3; A (dm3 mol−1 s−1) = (7.079 ± 0.035) × 1016, (1.413 ± 0.011) × 1017, and (9.772 ± 0.027) × 1020 for X = Cl, Br, and I respectively. An outer – sphere mechanism is proposed for all the reactions. 相似文献
18.
19.
Electrocatalytic oxygen reduction was studied on a RuxFeySez(CO)n cluster catalyst with Vulcan carbon powder dispersed into a Nafion film coated on a glassy carbon electrode. The synthesis
of the electrocatalyst as a mixture of crystallites and amorphous nanoparticles was carried out by refluxing the transition
metal carbonyl compounds in an organic solvent. Electrocatalysis by the cluster compound is discussed, based on the results
of rotating disc electrode measurements in a 0.5 M H2SO4. A Tafel slope of −80.00±4.72 mV dec−1 and an exchange current density of 1.1±0.17×10−6 mA cm−2 was calculated from the mass transfer-corrected curve. It was found that the electrochemical reduction reaction follows the
kinetics of a multielectronic (n=4e−) charge transfer process producing water, i.e. O2+4H++4e−→2H2O.
Electronic Publication 相似文献
20.
A. V. Belyaev S. G. Kozlova D. P. Pishchur N. K. Moroz S. N. Vorob’eva 《Russian Journal of Inorganic Chemistry》2016,61(3):291-295
Complex salts [Rh(H2O)6]PO4 (I) and [Rh(H2O)6]PO4 · H2O (II) were obtained. Dehydration processes of compounds I and II were studied by thermogravimetry and differential scanning calorimetry. The heat effect for the loss of 0.82 ± 0.01 H2O (hydration) molecule was found to be 54 ± 1 kJ/mol, while that for the loss of coordinated H2O is 47 ± 1 kJ/mol (for I) and 43 ± 1 kJ/mol (for II). The solid phases of dehydration products were studied by X-ray powder diffraction, IR and 31P MAS NMR spectroscopy, and they were found to be polymers. 相似文献