Determination of Activation Energy of the Iron Acceptor Pair Association and Dissociation Reaction

2015 ◽  
Vol 242 ◽  
pp. 230-235
Author(s):  
Kevin Lauer ◽  
Christian Möller ◽  
D. Debbih ◽  
Manuel Auge ◽  
Dirk Schulze
Keyword(s):  
Activation Energy ◽  
Iron Content ◽  
Reaction Rates ◽  
Activation Energies ◽  
Illumination Intensity ◽  
Dissociation Reaction ◽  
Acceptor Pair ◽  
Association Reaction

A method to measure the reaction rates of the iron acceptor pair association and dissociation is presented and applied. The activation energies of the dissociation and association reaction are determined for the acceptors boron, aluminum, gallium and indium. Additionally, the activation energies are reported for different illumination intensities. It is found that the activation energy of the association reaction varies for the investigated acceptors and that the activation energy of the dissociation reaction depends strongly on the illumination intensity. It is shown that neglecting of the dissociation reaction in the evaluation of relative interstitial iron content decrease causes a considerable overestimation of the activation energy of the iron acceptor association.

THE HYDROLYSIS OF ACID AMIDES IN CONCENTRATED HYDROCHLORIC ACID SOLUTIONS

1942 ◽  
Vol 20b (5) ◽  
pp. 73-81 ◽  
Author(s):  
B. S. Rabinovitch ◽  
C. A. Winkler
Keyword(s):  
Activation Energy ◽  
Hydrochloric Acid ◽  
Acid Concentration ◽  
Reaction Rates ◽  
Activation Energies ◽  
Acid Solutions ◽  
Hydrochloric Acid Solutions ◽  
Rate Of Hydrolysis ◽  
Hydrolysis Of

The Arrhenius constants have been evaluated for the hydrolysis of formamide, acetamide, propionamide, and benzamide in hydrochloric acid solutions over the concentration range 1 to 10 N. There is approximate correspondence between reaction rates and activation energies for the series of amides. An increase in observed activation energy with increasing acid concentration was found for all amides. The maximum in rate of hydrolysis, which occurs at higher acid concentrations, is discussed and accounted for by the variation in the Arrhenius constants with acid concentration.

The Determination of Kinetic Parameters of Transformer Oil and its Blends by Thermal Analysis

2012 ◽  
Vol 13 (4) ◽  
Author(s):  
Veresha Dukhi ◽  
Ajay Bissessur ◽  
Catherine Jane Ngila ◽  
Nelson Mutatina Ijumba
Keyword(s):  
Activation Energy ◽  
Weight Loss ◽  
Kinetic Parameters ◽  
Breakdown Voltage ◽  
Activation Energies ◽  
Transformer Oil ◽  
Dielectric Fluid ◽  
Differential Scanning Calorimetric ◽  
Significant Difference

Abstract The insulation of transformer oil comprise of two practices: paper and dielectric fluid (such as mineral transformer oil). Ageing of these oils occur mainly by thermal, electrical and oxidative stresses. This paper describes the determination of kinetic parameters of a naphthenic based transformer oil and its blends based on the Ozawa, Flynn and Wall (OFW) and Kissinger models using data obtained from thermogravimetric analysis (TGA) and differential scanning calorimetric (DSC), plots. Virgin oil and its blends were analysed from an initial temperature range of 20-25 ºC to 300 ºC at temperature ramps of 1, 2, 4, 6, 8 and 10 ºC min-1. The OFW method in conjunction with TGA data was used to calculate the apparent decomposition activation energies at each of the selected weight loss (% conversion or α) values. The activation energies at 10% weight loss were found to be 57.0, 63.7 and 69.3 kJ mol-1 for BHT-B (virgin oil-2,6-di-tert-butyl-4-methylphenol blends), DBP-B (virgin oil-2,6-di-tert-butylphenol blends) and VO (virgin transformer oil), respectively. However using this method the activation energy (Ea) of the oils showed no significant difference between virgin oil and its blends. DSC curves revealed that the decomposition reaction was exothermic in nature. From DSC data the activation energy was determined using two separate models: OFW and Kissinger models. Decomposition activation energy obtained from DSC data showed no significant difference when applied to these two models. Dissipation factor tests showed superior results for the blends when compared to those of virgin transformer oil. However, the blends showed substantial reductions in their dielectric breakdown voltage. The implication of the reduced breakdown voltage is that the blends show poorer dielectric strength in comparison to virgin transformer oil.

Chemical Kinetics

2021 ◽  
pp. 228-254
Author(s):  
Christopher O. Oriakhi
Keyword(s):  
Activation Energy ◽  
Chemical Kinetics ◽  
Chemical Reactions ◽  
Half Life ◽  
Reaction Rates ◽  
Effect Of Temperature ◽  
Collision Theory ◽  
Rate Laws ◽  
Reaction Orders

Chemical Kinetics discusses the rate at which chemical reactions occur and how these rates can be expressed mathematically, with a review of the factors which affect reaction rates. Topics presented with a numerical focus include reaction rate measurements, rate laws and their components including rate constants, determination of reaction orders from integrated rate laws, and effects of temperature on rates. Reaction half life and its determination are discussed. Collision theory, which forms the basis of the rate law, is presented with emphasis on the effect of temperature on the rate constant and the rate. The Arrhenius equation and the concept of activation energy are discussed with illustrative calculations for determining the energy of activation.

Activation Energy and NBO Interaction Approaches to the Determination of the Relative Resonance Acceptor Strengths of CN, NO, COMe, CHO and NO2 Groups from the Ring-Opening of 1,2-Benzo-3-Carbomethoxycyclobutenes

2019 ◽  
Author(s):  
Veejendra Yadav ◽  
Arpita Yadav
Keyword(s):  
Activation Energy ◽  
Interaction Energy ◽  
Ring Opening ◽  
Activation Energies ◽  
Interaction Energies ◽  
Differential Activation ◽  
Transition Structures

<p>The relative resonance-acceptor ability based on the activation energies for the outward ring-openings of 1,2-benzo-3-carbomethoxycyclobutenes bearing CN, NO, COMe, CHO and NO<sub>2</sub> as C6 and C7 substituents is different from that based on the s<sub>C3C4</sub>-p*<sub>C1C2</sub> interactions in the inward opening transition structures. The differential activation energy (∆G<sup>‡</sup>) predicts outward ring-opening and, in contrast, the differential s<sub>C3C4</sub>-p*<sub>C1C2</sub> interaction energy predicts inward opening, throughout. The relative resonance-acceptor ability estimated from the s<sub>C3C4</sub>-p*<sub>C1C2</sub> interaction energies is more realistic than that from the activation energies.</p>

The significance of reactions of low activation energies to the mechanism of combustion

1955 ◽  
Vol 230 (1182) ◽  
pp. 331-342 ◽  
Keyword(s):  
Activation Energy ◽  
Flame Propagation ◽  
Reaction Rates ◽  
Activation Energies ◽  
Chain Branching ◽  
Auto Ignition ◽  
Chain Breaking ◽  
Controlling Processes

The effect of the magnitude of activation energy on reaction rates has been examined. The conclusions suggest that a valid approximation to combustion mechanisms should be obtainable from a consideration of a single rate-controlling chain-branching and a single rate-controlling chain-breaking step. This concept has been applied in turn to homogeneous auto-ignition, ignition lags, limits of inflammability, flame propagation and burning velocities, resulting in a simple co-ordinating scheme. The formulae derived imply methods of identification of the rate-controlling processes from measurable flame properties.

scholarly journals Assay of β-N-acetylhexosaminidase isoenzymes in different biological specimens by means of determination of their activation energies

1998 ◽  
Vol 44 (2) ◽  
pp. 226-231 ◽  
Author(s):  
Luis F Pérez ◽  
J Carlos Tutor
Keyword(s):  
Activation Energy ◽  
Cerebrospinal Fluid ◽  
Catalytic Activity ◽  
Seminal Plasma ◽  
Activation Energies ◽  
Thermodynamic Method ◽  
Heat Inactivation ◽  
Specific Substrate ◽  
Isoenzyme Composition

Abstract The activation energy (Ea) of β-N-acetylhexosaminidase (Hex, EC 3.2.1.52) was determined with 3,3′-dichlorophenylsulfonphthaleinyl-N-acetyl-β-d-glucosaminide as substrate, with a much higher value being found for the Hex B isoenzyme (Ea = 75.1 kJ/mol) than for the Hex A isoenzyme (Ea = 41.8 kJ/mol). This fact allowed for the development of a fast and reliable thermodynamic method to determine the isoenzyme composition of Hex in different biological specimens (serum/plasma, saliva, cerebrospinal fluid, seminal plasma, urine, and leukocyte lysates). The results in serum given by the proposed method may be superimposed upon those obtained by the heat inactivation assay of O’Brien et al. (N Engl J Med 1970;273:15–20), and the catalytic activity calculated for Hex A offers a good correlation with that obtained by using the specific substrate 4-methylumbelliferyl-N-acetyl-β-d-glucosaminide-6 sulfate (n = 25, r = 0.953).

Annealing Kinetics of Neutron?Irradiated Aluminium and Copper

1960 ◽  
Vol 13 (2) ◽  
pp. 347 ◽  
Author(s):  
TH Blewitt ◽  
RR Coltman ◽  
CE Klabunde
Keyword(s):  
Activation Energy ◽  
Activation Energies ◽  
Slope Method ◽  
Measured Activation Energy ◽  
Measured Activation ◽  
Kinetics Of ◽  
Constant Activation Energy

Activation energies for the annealing of copper and aluminium following reactor bombardment near 4 OK have been measured in the range from 10 to 40 OK. Both the change in slope method and the isothermal technique method were utilized with the assumption that a constant activation energy existed. Computations of the number of jumps involved from the measured activation energy result in an impossibly small number. It is obvious that the method for determination of the activation energies is not applicable, probably because of the non-uniqueness of the activation energy.

A CRITICAL APPRAISAL OF THE DETERMINATION OF ACTIVATION ENERGY OF TL PEAKS BY KIRSH METHOD

2005 ◽  
Vol 19 (27) ◽  
pp. 1387-1396
Author(s):  
MANABESH BHATTACHARYA
Keyword(s):  
Activation Energy ◽  
Differential Equations ◽  
Critical Appraisal ◽  
Activation Energies ◽  
Recombination Center ◽  
Coupled Differential Equations

An attempt has been made to assess critically the suitability of Kirsh method for synthetic TL peaks obtained by solving the set of coupled differential equations. TL peaks represented by three different models namely (i) One Trap One Recombination center (OTOR), (ii) Non-interactive MultiTrap System (NMTS) and (iii) Interactive MultiTrap System (IMTS) have been taken into consideration. It has been found that Kirsh method yields resonably good values of activation energy except for the NMTS model. The validity of the method has been adjudged further by applying it for the determination of activation energies of a number of experimental TL peaks of BeO .

scholarly journals Activation Energy and NBO Interaction Approaches to the Determination of the Relative Resonance Acceptor Strengths of CN, NO, COMe, CHO and NO2 Groups from the Ring-Opening of 1,2-Benzo-3-Carbomethoxycyclobutenes

2019 ◽  
Author(s):  
Veejendra Yadav ◽  
Arpita Yadav
Keyword(s):  
Activation Energy ◽  
Interaction Energy ◽  
Ring Opening ◽  
Activation Energies ◽  
Interaction Energies ◽  
Differential Activation ◽  
Transition Structures

<p>The relative resonance-acceptor ability based on the activation energies for the outward ring-openings of 1,2-benzo-3-carbomethoxycyclobutenes bearing CN, NO, COMe, CHO and NO<sub>2</sub> as C6 and C7 substituents is different from that based on the s<sub>C3C4</sub>-p*<sub>C1C2</sub> interactions in the inward opening transition structures. The differential activation energy (∆G<sup>‡</sup>) predicts outward ring-opening and, in contrast, the differential s<sub>C3C4</sub>-p*<sub>C1C2</sub> interaction energy predicts inward opening, throughout. The relative resonance-acceptor ability estimated from the s<sub>C3C4</sub>-p*<sub>C1C2</sub> interaction energies is more realistic than that from the activation energies.</p>

Fourier Transform Infrared Analysis of Evolved Gases: Determination of Activation Energies

1988 ◽  
Vol 42 (7) ◽  
pp. 1253-1258 ◽  
Author(s):  
Luis Antonio Sanchez ◽  
Mimi Y. Keating
Keyword(s):  
Activation Energy ◽  
Fourier Transform ◽  
Calcium Oxalate ◽  
Evolved Gas Analysis ◽  
Fourier Transform Infrared ◽  
Calcium Oxalate Monohydrate ◽  
Activation Energies ◽  
Infrared Analysis ◽  
Rate Dependency

The use of Fourier transform infrared evolved-gas analysis (FT-IR/EGA) to determine activation energies from the heating rate dependency of the maximum evolution of effluent is demonstrated. The mathematical considerations are similar to those normally applied to differential thermal analysis. The determination of the activation energy is substantiated with dehydration of calcium oxalate monohydrate during pyrolysis; the results are compared with thermogravimetry analysis results, and indicate that the activation energy in the dehydration step in the pyrolysis of calcium oxalate monohydrate is temperature dependent.

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