The adsorption of ethylene on silver(I) oxide. I. Rates of adsorption

1967 ◽  
Vol 20 (3) ◽  
pp. 399
Author(s):  
JA Allen ◽  
PH Scaife
Keyword(s):  
Activation Energy ◽  
Kinetic Data ◽  
Qualitative Explanation ◽  
Kcal Mole ◽  
Temperature Range ◽  
Elovich Equation

The rates of adsorption of ethylene on silver(I) oxide, Ag2O, have been measured in the temperature range 273-313�K. The kinetic data are analysed in terms of the generalized Elovich equation by methods developed and described in a previous paper.1 The activation energy derived from the rates at zero coverage is 15.6 kcal mole-1. The presence of isothermal anomalies is noted and the extent of each kinetic stage defined. A qualitative explanation of the existence of these stages is suggested.

The adsorption of ethylene oxide on silver(I) oxide

1967 ◽  
Vol 20 (5) ◽  
pp. 837
Author(s):  
JA Allen ◽  
PH Scaife
Keyword(s):  
Activation Energy ◽  
Ethylene Oxide ◽  
Heat Of Adsorption ◽  
Entire Temperature Range ◽  
Kcal Mole ◽  
High Coverage ◽  
Temperature Range ◽  
Elovich Equation

The adsorption of ethylene oxide on stabilized silver(I) oxide in the temperature range 210-373% comprises two processes: (i) A non-activated process with a heat of adsorption from 10.7 to 6.9 kcal mole-l depending on the coverage, which persists over the entire temperature range; ��� (ii) an activated process with an activation energy at zero coverage of 22.7 kcal mole-1, which occurs at temperatures greater than 250�K. Reaction between adsorbate and adsorbent ensues above 323%. The generalized Elovich equation has been found to apply to the activated process at high coverage, and an explanation for this is proposed.

The thermal decomposition of RDX at temperatures below the melting point. II. Activation energy

1970 ◽  
Vol 23 (4) ◽  
pp. 749 ◽  
Author(s):  
JJ Batten ◽  
DC Murdie
Keyword(s):  
Activation Energy ◽  
Thermal Decomposition ◽  
Melting Point ◽  
Kinetic Parameter ◽  
Arrhenius Equation ◽  
Kcal Mole ◽  
Decomposition Products ◽  
Sample Geometry ◽  
Temperature Range ◽  
Definition Of

The activation energy has been determined in the temperature range 170-198�. If the sample was spread the activation energy was independent of the definition of the kinetic parameter substituted in the Arrhenius equation and was 63 kcal mole-1. In the case of the unspread samples the activation energies of the induction, acceleration, and maximum rates were 49, 43, and 62 kcal mole-1 respectively. The effect that sample geometry has on the activation energy is attributed to gaseous decomposition products influencing the reaction.

THE PHOTOLYSIS OF MERCURY DIMETHYL WITH DEUTERIUM

1954 ◽  
Vol 32 (2) ◽  
pp. 113-116 ◽  
Author(s):  
Richard E. Rebbert ◽  
E. W. R. Steacie
Keyword(s):  
Activation Energy ◽  
Satisfactory Agreement ◽  
Kcal Mole ◽  
Temperature Range ◽  
Work Done

Mercury dimethyl was photolyzed in the presence of deuterium in the temperature range from 27 °C. to 253 °C. The activation energy for the reaction[Formula: see text]was found to be 12.7 ± 0.5 kcal./mole. This is in satisfactory agreement with the work done with acetone and deuterium.

Kinetics of the Reaction between Silver and Nitric Acid

1962 ◽  
Vol 15 (2) ◽  
pp. 181 ◽  
Author(s):  
JJ Batten
Keyword(s):  
Activation Energy ◽  
Nitric Acid ◽  
Induction Period ◽  
Acid Concentration ◽  
Maximum Rate ◽  
Kcal Mole ◽  
Temperature Range ◽  
Induction Rate ◽  
Rate Of Dissolution ◽  
Kinetics Of

The rate of dissolution of silver gauze in nitric acid at various concentrations and temperatures was measured in a static system. The solution process was measured by the weight of silver dissolved in various time intervals. In general, induction periods were observed, but after this period the dissolution proceeded with an appreciable velocity. To examine the influence of acid concentration and temperature on the kinetics of the reaction, the duration of the induction period, the rate of dissolution during this period, and the subsequent maximum rate were taken as kinetic parameters of the reaction. The induction rate was found to be highly dependent on the initial acid concentration (approx. seventh power), whereas over most of the concentration range accessible to study, the maximum rate was proportional to the square of the concentration. It was also observed that increase in temperature sharply increases the induction rate, but has little effect upon the subsequent maximum rate over most of the temperature range studied. The activation energy of the induction rate was greater than 20 kcal/mole, whereas that of the maximum rate was about 4 kcal/mole over most of the temperature range studied. This difference in the activation energy during and after the induction period is explained by a shift in the mechanism controlling the rate of the process from a chemical reaction at the surface to a diffusion process.

THE REACTION OF METHYL RADICALS WITH FORMALDEHYDE

1959 ◽  
Vol 37 (4) ◽  
pp. 672-678 ◽  
Author(s):  
S. Toby ◽  
K. O. Kutschke
Keyword(s):  
Activation Energy ◽  
Methyl Radicals ◽  
Kcal Mole ◽  
Formyl Radical ◽  
Temperature Range ◽  
Abstraction Reaction

Azomethane was photolyzed in the presence of up to 30 mole per cent formaldehyde and formaldehyde-d2 at temperatures from 80 °C to 180 °C. The value of the activation energy for the abstraction reaction with methyl radicals was found to be 6.2 kcal mole−1 for CH2O and 7.9 kcal mole−1 for CD2O. The results indicated that the formyl radical was stable over the temperature range studied.

scholarly journals The State of Water in Human and Dog Red Cell Membranes

1970 ◽  
Vol 55 (4) ◽  
pp. 451-466 ◽  
Author(s):  
F. L. Vieira ◽  
R. I. Sha'afi ◽  
A. K. Solomon
Keyword(s):  
Activation Energy ◽  
Cell Membrane ◽  
Apparent Activation Energy ◽  
Water Diffusion ◽  
Red Cells ◽  
Red Cell ◽  
Kcal Mole ◽  
Red Cell Membrane ◽  
Temperature Range ◽  
Human Red Cells

The apparent activation energy for the water diffusion permeability coefficient, Pd, across the red cell membrane has been found to be 4.9 ± 0.3 kcal/mole in the dog and 6.0 ± 0.2 kcal/mole in the human being over the temperature range, 7° to 37°C. The apparent activation energy for the hydraulic conductivity, Lp, in dog red cells has been found to be 3.7 ± 0.4 kcal/mole and in human red cells, 3.3 ± 0.4 kcal/mole over the same temperature range. The product of Lp and the bulk viscosity of water, η, was independent of temperature for both dog and man which indicates that the geometry of the red cell membrane is not temperature-sensitive over our experimental temperature range in either species. In the case of the dog, the apparent activation energy for diffusion is the same as that for self-diffusion of water, 4.6–4.8 kcal/mole, which indicates that the process of water diffusion across the dog red cell membrane is the same as that in free solution. The slightly, but significantly, higher activation energy for water diffusion in human red cells is consonant with water-membrane interaction in the narrower equivalent pores characteristic of these cells. The observation that the apparent activation energy for hydraulic conductivity is less than that for water diffusion across the red cell membrane is characteristic of viscous flow and suggests that the flow of water across the membranes of these red cells under an osmotic pressure gradient is a viscous process.

The kinetics of the ordering process in triclinic NaAlSi3O8

1960 ◽  
Vol 32 (249) ◽  
pp. 436-454 ◽  
Author(s):  
J. D. C. McConnell ◽  
Duncan McKie
Keyword(s):  
Activation Energy ◽  
Kinetic Analysis ◽  
Vapour Pressure ◽  
Polymorphic Transformation ◽  
Water Vapour Pressure ◽  
Kcal Mole ◽  
Temperature Range ◽  
Self Diffusion ◽  
Dry Heating ◽  
Kinetics Of

SummaryA kinetic analysis is presented of the data of MacKenzie (1957) on the hydrothermal treatment of NaAlSi3O8 under isobaric, isothermal conditions in the temperature range 450° C. to 1000° C.The analysis indicates the existence of a smeared polymorphic transformation in the temperature range around 600° C. The activation energy for the transformation is about 60 kcal. mole−1 and has been equated with the process of self-diffusion involved in Al-Si ordering in the structure. Some dry-heating experiments and the influence of varying water vapour pressure are discussed.

PHOTOLYSIS OF MERCURY DIMETHYL

1953 ◽  
Vol 31 (7) ◽  
pp. 631-637 ◽  
Author(s):  
Richard E. Rebbert ◽  
E. W. R. Steacie
Keyword(s):  
Activation Energy ◽  
Kcal Mole ◽  
Temperature Range ◽  
Abstraction Reaction

The photolysis of mercury dimethyl was investigated over the temperature range from 125° to 250 °C. The results indicate that methane is formed only by an abstraction reaction and ethane is formed only by recombination, at least under the conditions used in these experiments. It is concluded that the activation energy of the reaction[Formula: see text]is 10.8 ± 0.3 kcal./mole.

THE PYROLYSIS OF DIALLYL (1,5-HEXADIENE)

1960 ◽  
Vol 38 (6) ◽  
pp. 827-834 ◽  
Author(s):  
D. J. Ruzicka ◽  
W. A. Bryce
Keyword(s):  
Activation Energy ◽  
Room Temperature ◽  
Hydrogen Abstraction ◽  
Radical Mechanism ◽  
Static System ◽  
Kcal Mole ◽  
Temperature Range ◽  
Gaseous Products ◽  
Mechanism Of Decomposition ◽  
Liquid Products

The mechanism of decomposition of diallyl has been studied in a static system in the temperature range 460–520 °C. The principal gaseous products (room temperature) were propylene, methane, ethylene, and 1-butene, and the liquid products were cyclopentene, cyclopentadiene, 1-hexene, and benzene. The over-all activation energy of decomposition was 31.3 ± 1.0 kcal/mole for an A factor of 107 sec−1. A mechanism of decomposition based on hydrogen abstraction by allyl and the addition of allyl to olefinic double bonds is proposed. Some decomposition by a non-radical mechanism may also occur.

The reaction of methanol vapour with silver(I) oxide

1964 ◽  
Vol 17 (5) ◽  
pp. 529
Author(s):  
JA Allen
Keyword(s):  
Carbon Dioxide ◽  
Thermal Decomposition ◽  
Carbon Monoxide ◽  
Gas Phase ◽  
Kinetic Data ◽  
Kcal Mole ◽  
Collision Model ◽  
Temperature Range ◽  
Methanol Vapour ◽  
The Mean

The reaction of methanol with silver(I) oxide has been studied in the temperature range 56.5-78.4�. For complete reduction of the oxide at 78.4�, the available oxygen is fully accounted for by the products, formaldehyde, formic acid, carbon monoxide, carbon dioxide, and water. In the temperature range 56.5-70.2� the net measured rates of formation of these products are expressed by equations of the form, ������������������ rate = Aexp(-E/RT), and the kinetic data are interpreted as the consecutive formation of the products on the surface without complete desorption to the gas phase between each step. For the dominant product, carbon dioxide, at the mean temperature the values of A and E are 1028.5 μg oxygen per minute and 41.3 kcal mole-1 respectively. The former is interpreted in terms of a simple collision model and the latter compared with values obtained for the thermal decomposition of the oxide.

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