Thermal decomposition of the ethyl radical

1967 ◽  
Vol 45 (22) ◽  
pp. 2795-2803 ◽  
Author(s):  
L. F. Loucks ◽  
K. J. Laidler
Keyword(s):  
Thermal Decomposition ◽  
Entire Range ◽  
Pressure Range ◽  
Heat Of Formation ◽  
Unimolecular Decomposition ◽  
Kcal Mole ◽  
Ethyl Radical ◽  
A Value ◽  
Kinetics Of ◽  
Best Fit

The kinetics of the thermal decomposition of the ethyl radical to give an ethylene molecule and a hydrogen atom were studied over the pressure range 4 to 650 mm Hg and the temperature range 400 to 500 °C; the mercury-photosensitized decomposition of ethane was used to generate the ethyl radical. The unimolecular decomposition of the ethyl radical was found to be pressure dependent over the entire range of pressures studied, with the order of reaction varying from 1.6 for the lowest pressures to 1.4 at the highest pressures. The extrapolated high-pressure and low-pressure rate constants for the decomposition of the ethyl radical are given by [Formula: see text] [Formula: see text]A best fit of the Kassel equation to the observed pressure dependence shows that s = 8 for this reaction. The results lead to a value of 98 1 kcal/mole for the bond dissociation energy D(C2H5—H). The heat of formation of the ethyl radical was calculated to be 30.0 and 26.2 kcal/mole for 0 °K and 25 °C respectively.

scholarly journals The dissociation energy of the C-N bond in benzylamine

1949 ◽  
Vol 198 (1053) ◽  
pp. 285-292 ◽  
Keyword(s):  
Activation Energy ◽  
Thermal Decomposition ◽  
Dissociation Energy ◽  
Heat Of Formation ◽  
Molar Ratio ◽  
Kcal Mole ◽  
First Order ◽  
First Order Kinetics ◽  
Permanent Gases ◽  
Kinetics Of

The kinetics of the thermal decomposition of benzylamine were studied by a flow method using toluene as a carrier gas. The decomposition produced NH 3 and dibenzyl in a molar ratio of 1:1, and small quantities of permanent gases consisting mainly of H 2 . Over a temperature range of 150° (650 to 800° C) the process was found to be a homogeneous gas reaction, following first-order kinetics, the rate constant being expressed by k = 6 x 10 12 exp (59,000/ RT ) sec. -1 . It was concluded, therefore, that the mechanism of the decomposition could be represented by the following equations: C 6 H 5 . CH 2 . NH 2 → C 6 H 5 . CH 2 • + NH 2 •, C 6 H 5 . CH 3 + NH 2 •→ C 6 H 5 . CH 2 • + NH 3 , 2C 6 H 5 . CH 2 •→ dibenzyl, and the experimentally determined activation energy of 59 ± 4 kcal./mole is equal to the dissociation energy of the C-N bond in benzylamine. Using the available thermochemical data we calculated on this basis the heat of formation of the NH 2 radical as 35.5 kcal./mole, in a fair agreement with the result obtained by the study of the pyrolysis of hydrazine. A review of the reactions of the NH 2 radicals is given.

Mass transfer and kinetics of the chemical vapor deposition of SiC onto fibers

1998 ◽  
Vol 13 (8) ◽  
pp. 2251-2261 ◽  
Author(s):  
W. Jack Lackey ◽  
Sundar Vaidyaraman ◽  
Bruce N. Beckloff ◽  
Thomas S. Moss III ◽  
John S. Lewis
Keyword(s):  
Mass Transfer ◽  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Atmospheric Pressure ◽  
Chemical Vapor ◽  
Total Flow ◽  
A Value ◽  
Factor Expression ◽  
Kinetics Of ◽  
Best Fit

An internally consistent set of data was generated for the chemical vapor deposition (CVD) of SiC from methyltrichlorosilane (MTS) and H2 at atmospheric pressure. A moving fiber tow was used as the substrate. Coating rates between 0.3 and 3.7 µm/min and deposition efficiencies between 24 and 48% were obtained for MTS and H2 flow rates in the range 30 to 200 cm3/min and 300 to 2000 cm3/min, respectively. The data were analyzed and found to be best fit under a mass transfer regime. Based on this fit, a value of the constant in the Chilton–Colburn j factor expression for a moving fiber tow was estimated to be 2.74 × 10−6 with a standard deviation of 3.2 × 10−7. The efficiency of the reaction was found to decrease with increases in the total flow rate, indicating that the effect of the decreased residence time of reagents in the reactor was larger than the increase in the mass transfer coefficient. Finally, a comparison between the efficiencies for a stationary and a moving tow revealed that the moving tow had a higher efficiency, possibly due to a disruption of the boundary layer by the tow motion or due to the decrease in the canning of the moving tow.

FREE RADICALS BY MASS SPECTROMETRY: XXXV. THE HEAT OF FORMATION OF ALLYL RADICAL FROM BIALLYL PYROLYSIS

1966 ◽  
Vol 44 (18) ◽  
pp. 2211-2217 ◽  
Author(s):  
J. B. Homer ◽  
F. P. Lossing
Keyword(s):  
Mass Spectrometry ◽  
Activation Energy ◽  
Thermal Decomposition ◽  
Total Pressure ◽  
Heat Of Formation ◽  
Kcal Mole ◽  
Allyl Radical ◽  
First Order ◽  
Secondary Reactions ◽  
Gas Pressures

The thermal decomposition of biallyl has been investigated from 977 – 1 070 °K at helium carrier gas pressures of 10–50 Torr. Under these conditions the rate of central C—C bond fission to give two allyl radicals can be measured without interference from secondary reactions. The reaction at the pressures employed is first order with respect to biallyl, but between first and second order in the total pressure. The temperature dependence of the rate constants, extrapolated to infinite pressure, and corrected to 298 °K, gives an activation energy of 45.7 kcal/mole for the reaction, corresponding to ΔHf(allyl) = 33.0 kcal/mole.

Kinetics of the Mercury-Photosensitized Decomposition of Propane. Part II. Reactions of the Propyl Radicals

1971 ◽  
Vol 49 (4) ◽  
pp. 549-554 ◽  
Author(s):  
M. M. Papic ◽  
K. J. Laidler
Keyword(s):  
Activation Energy ◽  
High Pressure ◽  
Kinetic Parameters ◽  
Dissociation Energy ◽  
Heat Of Formation ◽  
Entropy Changes ◽  
A Value ◽  
Yield Information ◽  
Temperature And Pressure ◽  
Kinetics Of

The results of the previous paper are analyzed to yield information about the reactions of the n-propyl and i-propyl radicals. The various combination and disproportionation reactions are considered. The rate of decomposition of the n-propyl radical was determined as a function of temperature and pressure, and limiting high-pressure and low-pressure kinetic parameters were obtained. The high-pressure activation energy is 32.6 kcal mol−1, and this leads to a value of 24.3 kcal mol−1 for the dissociation energy of the C—C bond in the n-propyl radical, to 22.2 kcal mol−1 for its heat of formation, and to 99.1 kcal mol−1 for the primary C—H dissociation energy in propane. Entropy changes are also calculated from the results.For the decomposition of the i-propyl E∞ = 38.7 kcal mol−1, and this leads to 37.7 kcal mol−1 for the C—H bond dissocation energy in this radical and to 19.3 kcal mol−1 for its heat of formation. The secondary C—H dissociation energy in propane is calculated to be 96.2 kcal mol−1. Corresponding entropy changes are calculated.

Kinetic Study of the Pyrolysis of Formaldehyde

1972 ◽  
Vol 50 (7) ◽  
pp. 992-998 ◽  
Author(s):  
C. J. Chen ◽  
D. J. McKenney
Keyword(s):  
Activation Energy ◽  
Thermal Decomposition ◽  
Carbon Monoxide ◽  
Kinetic Study ◽  
Pressure Range ◽  
Heterogeneous Reaction ◽  
Experimental Results ◽  
Arrhenius Parameters ◽  
Rate Laws ◽  
Kinetics Of

Kinetics of the thermal decomposition of pure formaldehyde were studied over a temperature range of 466–516 °C and a pressure range of ~ 50–160 Torr. Arrhenius parameters and rate laws were determined for carbon monoxide, hydrogen and methanol as follows:[Formula: see text]A mechanism is postulated which is qualitatively consistent with the experimental results but the activation energy for reaction 1[Formula: see text]is ~15 kcal/mol lower than predicted from recent thermochemical data, suggesting the possibility of a heterogeneous reaction.

THE KINETICS OF THE THERMAL DECOMPOSITION OF PYRITE

1966 ◽  
Vol 44 (10) ◽  
pp. 1191-1195 ◽  
Author(s):  
A. W. Coats ◽  
Norman F. H. Bright
Keyword(s):  
Thermal Decomposition ◽  
Weight Loss ◽  
Reaction Rate ◽  
Argon Atmosphere ◽  
Kcal Mole ◽  
Linear Rate ◽  
Nucleation Stage ◽  
Spring Balance ◽  
Rate Of Progression ◽  
Kinetics Of

The kinetics of the thermal decomposition of purified pyrite to pyrrhotite and sulfur in a dynamic argon atmosphere have been studied over the temperature range 600 to 653 °C. The reaction was followed by the rate of weight loss as indicated by a quartz spring balance and also by the rate of progression of the pyrite/pyrrhotite interface into a cylindrical, compressed, polycrystalline pellet. The temperature coefficient of the reaction was found to be 69.5 ± 5.9, 64.7 ± 3.3, and 66.9 ± 5.1 kcal mole−1, when the results were processed in three different ways. The pyrite/pyrrhotite interface was found to progress at a linear rate into the pellet at a given temperature; equations were derived to express the variation of reaction rate with temperature. Attempts to follow the early nucleation stage of the decomposition, using massive mineral crystals, proved unsuccessful.

Sign in / Sign up

Export Citation Format

Share Document