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1.
Lajos Szirovicza 《Reaction Kinetics and Catalysis Letters》2009,96(2):311-317
The kinetics of the reactions of ClO3
− with HSO3
− and H2SO3 was studied by measuring the concentration of [Cl−] and [H+] both in chlorate-bisulfite and chlorate-sulfite/bisulfite solutions. A reaction mechanism was applied for simulation of
the experimental observations. Rate constants k1 = (1±0.5)·10−4 M−1 s−1 and k2 = (0.23±0.01) M−1 s−1 were determined for the following reactions:
Rate constant k1 was obtained directly from the experimental results of chloratesulfite/ bisulfite reactions, where reaction (1) is predominant.
Rate constant k2 was obtained by computer fitting of [Cl−] and [H+] to the experimental values both in chlorate-bisulfite and chlorate-sulfite/bisulfite reactions. 相似文献
| ((1)) |
| ((2)) |
2.
Conformations of fold part in isotactic polypropylene lamella with diamond lattice model 总被引：1，自引：0，他引：1
Ｉｎｔｈｅｆｉｅｌｄｏｆｐｏｌｙｍｅｒｐｈｙｓｉｃｓ,ｔｈｅｃｒｙｓｔａｌｌｉｎｅｓｔａｔｅｏｆｐｏｌｙｍｅｒｓｈａｓｌｏｎｇｂｅｅｎｏｆｉｎｔｅｒｅｓｔ.ＴｈｅｅｘｉｓｔｅｎｃｅｏｆｐｏｌｙｍｅｒｓｉｎｇｌｅｃｒｙｓｔａｌｗａｓｆｉｒｓｔｄｉｓｃｏｖｅｒｅｄｂｙＪａｃｃｏｄｉｎｅ[1]ｉｎ1955.Ｔｈｅｔｈｉｃｋｎｅｓｓｏｆｍｏｓｔｓｏｌｕｔｉｏｎｇｒｏｗｔｈｃｒｙｓｔａｌｓｉｓｆｏｕｎｄｔｏｂｅｏｆｔｈｅｏｒｄｅｒｏｆ～10ｎｍ.Ｔｈｉｓｏｂｓｅｒｖａｔｉｏｎｉｓｓｏｍｅｗｈａｔｓｕｒｐｒｉｓｉｎｇ.Ｓ… 相似文献
3.
Rate constants for the gas phase reactions of hydroxyl radicals and chlorine atoms with a number of ethers have been determined at 300 ± 3 K and at a total pressure of 1 atmosphere. Both OH radical and chlorine atom rate constants were determined using a relative rate technique. Values for the rate constants obtained are as follows.
The above relative rate constants are based on the values of k(OH + pentane)=[3.94 ± 0.98]×10?12 and k(OH + diethyl ether)=[13.6 ± 2.26] × 10?12 cm3 molecule?1 s?1 in the case of the hydroxyl reactions. In the case of the chlorine atom reactions, the above rate constants are based on values of k(Cl + ethane)=[5.84 ± 0.88] × 10?11 and k(Cl + diethyl ether)=[25.4 ± 8.05] × 10?11 cm3 molecule?1 s?1. The quoted errors include ±2σ from a least squares analysis of our slopes plus the uncertainty associated with the reference rate constants. Atmospheric lifetimes calculated with respect to reaction with OH radicals are based on a tropospheric OH radical concentration of (7.7 ± 1.4) × 105 radicals cm?3, and lifetimes with respect to reaction with Cl atoms are based on a tropospheric Cl atom concentration of 1 × 103 atoms cm?3. Observed trends in the relative rates of reaction of hydroxyl radicals and chlorine atoms with the ethers studied is discussed. The significance of the calculated tropospheric lifetimes is also reviewed. © 1993 John Wiley & Sons, Inc. 相似文献
| compound | kOH×1012(cm3 molecule?1 s?1) | kC1×1011(cm3 molecule?1 s?1) |
|---|---|---|
| Hexane | 5.53 ± 1.55 | — |
| 2-Chloro ethyl methyl ether | 4.92 ± 1.09 | 14.4 ± 5.0 |
| 2,2-Dichloro ethyl methyl ether | 2.37 ± 0.50 | 4.4 ± 1.6 |
| 2-Bromo ethyl methyl ether | 6.94 ± 1.38 | 16.3 ± 5.4 |
| 2-Chloro,1,1,1-trifluoro ethyl ethyl ether | <0.3 | 0.30 ± 0.10 |
| Isoflurane | <0.3 | <0.1 |
| Enflurane | <0.3 | <0.1 |
| Di-i-propyl ether | 11.08 ± 2.26 | 16.3 ± 5.4 |
| Diethyl ether | — | 25.8 ± 4.4 |
4.
Yakov I. Tur’yan Fernando Mata Jorge Moyano Pavel Gorenbein Ron Kohen 《Journal of Solid State Electrochemistry》2007,11(1):10-20
The theory of the polarographic catalytic currents (mechanism CE) has been developed for the system: Ni2+-L-Xp− where L: pyridine (Py), nicotinamide (NA), N,N-diethylnicotinamide (DEN), nicotine (NC) and Xp−: NO−
3, AcO−, HPO2−
4 . The theory is based on the kinetic parallel heterogeneous catalytic reactions:
with the use of Langmuir’s adsorbed isotherm. The kinetic equations obtained for average and instantaneous currents allowed
to determine the Langmuir’s parameters (NA<DEN<NC), kinetic parameters and the contribution of reactions 1a and b to the summary catalytic currents. The k
h″ value rises with the increase of the NiX2−p stability constant. The correlation k
h″≫k
h′ was explained by the additional effect of the field electrode through Xp−. These effects base the reaction 1b instead of accepted early alternative reaction of the ligand exchange. In spite of the fact that k
h″≫k
h′, the contribution of the reaction 1a in the summary catalytic current attained more than 60% (Py, DEN) due to the influence of the ψ0 potential.
Dedicated to Professor Zbigniew Galus on the occasion of his 70th birthday and in recognition of his many contributions to
electrochemistry 相似文献
| (1a) |
| (1b) |
5.
C Paz-Ramos C A Cerdeiriña J Troncoso L Romaní 《Journal of Thermal Analysis and Calorimetry》2006,83(2):263-268
In the search of a useful
method for determining excess enthalpies as a function of temperature Calvet
calorimetry was employed. To this end, excess molar enthalpies
at 298.15 and 333.15 K and excess molar heat capacities
within 283.15–333.15 K were
determined for the 1-decanol+n-decane system
over the whole composition range. An isothermal flow Calvet-type calorimeter
was used for
measurements, whereas
were determined by means of a Setaram
Micro DSC calorimeter. Excess enthalpies within 283.15–333.15 K were
indirectly obtained through the integration of
(T) data using
at 298.15 K. The results obtained at 333.15 K agreed with those
determined directly, implying the thermodynamic consistency of the measured
data and, therefore, the reliability of the indirect method. 相似文献
6.
The relative hydroxyl radical reaction rate constants from the simulated atmospheric oxidation of selected acetates and other esters have been measured. Reactions were carried out at 297 ± 2 K in 100-liter FEP Teflon®-film bags. The OH radicals were generated from the photolysis of methyl nitrite in pure air. Using a rate constant of 2.63 × 10?11 cm3 molecule?1 s?1 for the reaction of OH radicals with propene, the principal reference organic compound, the rate constants (×1012 cm3 molecule?1 s?1) obtained for the acetates and esters used in this study are:
Error limits represent 2σ from linear least-squares analysis of data. A linear correlation was observed for a plot of the measured relative rate constants vs. the number of CH2 groups per molecule of the following acetates: methyl acetate, ethyl acetate, n-propyl acetate, butyl acetate, and pentyl acetate. © 1993 John Wiley & Sons, Inc. 相似文献
| n–propyl acetate | 3.42 ± 0.87 |
| n–butyl acetate | 5.71 ± 0.94 |
| n–pentyl acetate | 7.53 ± 0.48 |
| 2–ethoxyethyl acetate | 10.56 ± 1.31 |
| 2–ethoxyethyl isobutyrate | 13.56 ± 2.32 |
| 2–ethoxyethyl methacrylate | 27.22 ± 2.06 |
| 4–pentene-1-yl acetate | 43.40 ± 3.85 |
| 3–Ethoxyacrylic acid ethyl ester | 33.30 ± 1.22 |
7.
Rate constants for the gas‐phase reactions of hydroxyl radicals and chlorine atoms with a series of alcohols have been determined by using the relative method. The experiments were performed at 295 ± 2 K and at 1 atmospheric pressure. The obtained values of the rate constants in units of 10?12 cm3 molecule?1 s?1 are as follows:
The above relative rate constants are based on the values (in units of 10?12 cm3 molecule?1 s?1) of k(OH + propane) = 1.08, k(OH + cyclohexane) = 7.22, k(Cl + propane) = 131 and k(Cl + cyclohexane) = 307. The results are compared with previous determinations. © 2002 Wiley Periodicals, Inc. Int J Chem Kinet 35: 81–87, 2003 相似文献
| Alcohol | Rate Constants for OH with | Rate Constants for Cl with | ||
|---|---|---|---|---|
| Propane | Cyclohexane | Propane | Cyclohexane | |
| Ethyl alcohol | 3.40 ± 0.25 | – | 103 ± 4 | 96 ± 7 |
| n‐Propyl alcohol | 5.47 ± 0.44 | – | 153 ± 13 | 147 ± 11 |
| Isopropyl alcohol | 5.31 ± 0.39 | – | 73.5 ± 3.7 | 82.7 ± 7.4 |
| n‐Butyl alcohol | 8.66 ± 0.66 | – | 211 ± 11 | 223 ± 10 |
| Isobutyl alcohol | 9.08 ± 0.35 | 9.59 ± 0.45 | 182 ± 4 | 196 ± 11 |
| tert‐Butyl alcohol | 1.11 ± 0.07 | – | 31.5 ± 2.4 | 34.1 ± 2.5 |
| n‐Pentyl alcohol | 12.2 ± 1.0 | 12.4 ± 0.5 | 257 ± 25 | 258 ± 12 |
| Isopentyl alcohol | 13.8 ± 0.5 | 13.2 ± 1.1 | 237 ± 7 | 235 ± 9 |
8.
The hydrolytic behavior of antimonic acid, Sb(OH)5o, was experimentally investigated, at fixed temperatures within the range 10–40 °C, by both titration of dilute Na-antimonate
solutions with HClO4 and single-point pH measurements of diluted Sb(OH)5o solutions. The thermodynamic constants, K
a, for the reaction:
were derived at different controlled temperatures, based on pH measurements, applying suitable mass and electrical balances
and correcting the concentrations of ionic species for medium effects. From the resulting log 10
K
a values, those of the corresponding isocoulombic equilibrium reaction:
were computed and used to derive its thermodynamic properties. These were finally combined with the corresponding thermodynamic
properties of the water association reaction, to obtain robust estimations of ΔG
ro, ΔS
ro and ΔH
ro for the ionogenic reaction. These are the first thermodynamic data at temperatures different from 25 °C for the ionization
reaction of Sb(OH)5o. The results of the present work confirm that Sb(OH)5o is a moderately weak and monoprotic acid with a pK
a of 2.848 at 25 °C. 相似文献
9.
K. S. Gupta R. K. Mehta A. K. Sharma P. K. Mudgal S. P. Bansal 《Transition Metal Chemistry》2008,33(7):809-817
For getting an insight into the mechanism of atmospheric autoxidation of sulfur(IV), the kinetics of this autoxidation reaction
catalyzed by CoO, Co2O3 and Ni2O3 in buffered alkaline medium has been studied, and found to be defined by Eqs. I and II for catalysis by cobalt oxides and
Ni2O3, respectively.
The values of empirical rate parameters were: A{0.22(CoO), 0.8 L mol−1s−1 (Co2O3)}, K
1{2.5 × 102 (Ni2O3)}, K
2{2.5 × 102(CoO), 0.6 × 102 (Co2O3)} and k
1{5.0 × 10−2(Ni2O3), 1.0 × 10−6(CoO), 1.7 × 10−5 s−1(Co2O3)} at pH 8.20 (CoO and Co2O3) and pH 7.05 (Ni2O3) and 30 °C. This is perhaps the first study in which the detailed kinetics in the presence of ethanol, a well known free
radical scavenger for oxysulfur radicals, has been carried out, and the rate laws for catalysis by cobalt oxides and Ni2O3 in the presence of ethanol were Eqs. III and IV, respectively.
For comparison, the effect of ethanol on these catalytic reactions was studied in acidic medium also. In addition, alkaline
medium, the values of the inhibition factor C were 1.9 × 104 and 4.0 × 103 L mol−1 s for CoO and Co2O3, respectively; for Ni2O3, C was only 3.0 × 102 only. On the other hand, in acidic medium, the values of this factor were all low: 20 (CoO), 0.7 (Co2O3) and 1.4 (Ni2O3). Based on these results, a radical mechanism for CoO and Co2O3 catalysis in alkaline medium, and a nonradical mechanism for Ni2O3 in both alkaline and acidic media and for cobalt oxides in acidic media are proposed. 相似文献
| (I) |
| (II) |
| (III) |
| (IV) |
10.
Abstact The reduction process of silica supported cobalt catalyst was studied by thermal analysis technique. The reduction of the
catalyst proceeds in two steps:
which was validated by the TPR and in-situ XRD experiments. The kinetic parameters of the reduction process were obtained with a comparative method. For the first step,
the activation energy, E
a, and the pre-exponential factor, A, were found to be 104.35 kJ mol−1 and 1.18·106∼2.45·109 s−1 respectively. The kinetic model was random nucleation and growth and the most probable mechanism function was found to be
f(α)=3/2(1−α)[−ln(1−α)]1/3 or in the integral form: g(α)=[−ln(1−α)]2/3. For the second step, the activation energy, E
a, and the pre-exponential factor, A, were found to be 118.20 kJ mol−1 and 1.75·107∼2.45 · 109s−1 respectively. The kinetic model was a second order reaction and the probable mechanism function was f(α)=(1−α)2 or in the integral form: g(α)=[1−α]−1−1. 相似文献
11.
Rate constants for the reactions of OH radicals and Cl atoms with CH3ONO, C2H5ONO, n-C3H7ONO, n-C4H9ONO, and n-C5H11ONO have been determined at 298 ± 2 K and a total pressure of approximately 1 atm. The OH rate data were obtained using both the absolute rate technique of pulse radiolysis combined with kinetic spectroscopy and a relative rate method involving simultaneous measurement of the loss of the nitrite and the reference compound. The Cl rate constants were measured using the relative rate method. Values of the rate constants in units of 10?13 cm3 molecule?1 s?1 are:
When compared to rate data for the corresponding alkanes the results show that the -ONO group decreases the rate constant for H atom abstraction by the OH radical from groups bonded to the -ONO group and also decreases that for groups in the β position. Similar results were found for the reaction of Cl atoms with these compounds. The results are discussed in terms of reactivity trends. 相似文献
| Relative Cl | Relative OH | Absolute OH | |
|---|---|---|---|
| CH3ONO | 94.4 ± 7.4 | 3.0 ± 1.0 | 2.6 ± 0.5 |
| C2H5ONO | 295 ± 13 | 7.0 ± 1.5 | 7.0 ?1.1 |
| n-C3H7ONO | 646 ± 58 | 11.0 ± 1.5 | 12.0 ± 0.5 |
| n-C4H9ONO | 1370 ± 58 | 22.7 ± 0.8 | 27.2 ± 6.0 |
| n-C5H11ONO | 2464 ± 444 | 37.4 ± 5.0 | 42.5 ± 8.0 |
12.
The compounds {[Fe(phen)3]2+(TCNQ–TCNQ)2−) · 2(CH3OH)} (FIWPRD), {[Fe(C5H5)(C5H4CH2NMe3)]+)(TCNQ−) (IKONOL), and {[Cu(1,4,5,12-tetraazacyclo-pentadecane)]2+(TCNQ−)2} (AVOJEA) were reported in the non-centrosymmetric space groups Cc (#9), Pna21 (#33), and P1 (#1). Examination of the several sets of atomic coordinates shows that the space groups are more likely to be C2/c (#15), Pnma (#63), and (#2), respectively. Confirmation of the centrosymmetric models requires access to the diffraction intensities; unfortunately
these are not in the public domain.
相似文献
| Frank H. HerbsteinEmail: |
13.
The osmium(VIII) catalysed IO4
− oxidation of DMF in aqueous alkaline medium follows the rate law:
|
相似文献
14.
Compensation effect as a consequence of vibrational energy transfer in homogeneous and isotropic heat field 总被引：1，自引：1，他引：0
Nicolina Pop Gabriela Vlase T. Vlase N. Doca A. Mogoş A. Ioiţescu 《Journal of Thermal Analysis and Calorimetry》2008,92(1):313-317
By kinetics of decomposition of solids in both isothermal and non-isothermal conditions, the compensation effect (CE) is rather
a rule.
The topic of this work is to suggest an activation mechanism which leads to the dependences similar with CE.
The solid is assimilated to a system of the harmonic oscillator with a Bose-Einstein energy distribution.
Considering an activation process due to a vibrational energy transfer from a homogeneous and isotropic field of thermic oscillators
to the solid-state oscillator, the thermodynamic functions are in the relationship
15.
Z. L. Zhang M. H. Zhong J. Liu F. M. Liu Z. Z. Wang F. P. Zhong F. Wu 《Journal of Thermal Analysis and Calorimetry》1999,58(2):421-433
In this work some calorimetric measurements were also carried out on the electrorefining silver by using different current densities with a Calvet type microcalorimeter at room temperature. The ratio (R) of the measured heat (
16.
The following Arrhenius parameters have been determined for the hydrogen-abstraction reactions: R + (CH3)4Si → RH + (CH3)3SiCH3
17.
Rabindra N. Roy Lakshmi N. Roy Curtis A. Himes Sarah J. Richards Sean R. LeNoue Cole E. Denton Marie J. Pesek Chandra N. Roy Neha Sangoi Stephanie N. Gibbs Richard D. Shaffer 《Journal of solution chemistry》2005,34(9):1017-1031
The activity coefficients of HCl (γA) in aqueous mixtures of HCl and NdCl3 were determined by the electromotive-force (emf) measurement of cells without liquid junctions of the type:
18.
V. D. Belyaev V. V. Galvita V. A. Sobyanin 《Reaction Kinetics and Catalysis Letters》1998,63(2):341-348
The carbon dioxide reforming of methane in a cell with a solid oxygen-conducting electrolyte:
19.
O. V. Belousov Yu. V. Saltykov L. I. Dorokhova L. A. Solov’ev S. M. Zharkov 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2008,82(4):647-650
It was found that metastable equilibrium in the heterogeneous reaction
20.
Dubey Sapna Sharma Neetu Khandelwal Chandra L. Sharma Prem D. 《Transition Metal Chemistry》2003,28(2):176-181
The kinetics of osmium(VIII)-catalyzed oxidation of hypophosphite with hexacyanoferrate(III) in alkaline medium has been studied. The rate is independent of the concentration of the oxidant. The order with respect to hydroxide ion is variable. Rate law (1) conforms with the experimental observations.
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