Energy and Entropy of Activation of Propagation by the Free Polystyryl Anions and Their Ion Pairs. The Phenomenon of “Negative” Activation Energy.

1967 ◽  
Vol 89 (4) ◽  
pp. 796-803 ◽  
Author(s):  
T. Shimomura ◽  
K. J. Tolle ◽  
J. Smid ◽  
M. Szwarc
Keyword(s):  
Activation Energy ◽  
Ion Pairs ◽  
Entropy Of Activation

Some aspects of cis–trans-isomerization mechanisms

1968 ◽  
Vol 46 (6) ◽  
pp. 973-978 ◽  
Author(s):  
M. C. Lin ◽  
K. J. Laidler
Keyword(s):  
Activation Energy ◽  
Linear Relationship ◽  
Bond Energy ◽  
Reaction Mechanisms ◽  
Compensation Effect ◽  
Trans Isomerization ◽  
Entropy Of Activation ◽  
Partial Compensation

It is shown that there is a linear relationship between the activation energy for a thermal cis–trans isomerization and the heat of hydrogenation of the C=C bond. There is also a linear relationship between the entropy of activation and the heat of activation, there being a partial compensation effect. It is pointed out that the activation energy for these processes is very close to the π-bond energy of the C=C bond. The significance of these relationships is discussed in terms of the reaction mechanisms.

scholarly journals A comparative thermal decomposition kinetics on 1,2-bis(imino-4'-antipyrinyl)ethane and 4-N-(4'-antipyrylmethylidene)aminoantipyrine Cu(II) complexes with varying counter anions

2018 ◽  
Vol 3 (2) ◽  
pp. 108-115
Author(s):  
Tesfay Gebretsadik Ashebr ◽  
Wolfgang Linert ◽  
Nayathuparambil Thomas Madhu
Keyword(s):  
Activation Energy ◽  
Thermal Decomposition ◽  
Kinetic Studies ◽  
Decomposition Kinetics ◽  
Thermal Decomposition Kinetics ◽  
Ligand Field ◽  
Decomposition Kinetic ◽  
Exponential Factor ◽  
Entropy Of Activation ◽  
Thermal Decomposition Kinetic

A comparative thermal decomposition kinetic studies of Cu(II) complexes of 1,2-bis (imino-4-antipyrinyl) ethane(GA) and4-N-(4'-antipyrylmethylidene) aminoantipyrine (AA) with a variety of counter anions viz. ClO4-, NO3-, Cl- and Br- has been evaluated by TG analysis. The kinetic parameters activation energy (E), pre-exponential factor (A) and entropy of activation (∆S) were calculated by using Coats–Redfern equation. This study shows that the thermal decomposition kinetics has been controlled by the ligand field as well as the counter anions.

scholarly journals Kinetic Oxidation Studies of Pentoxifylline by N-Chlorosuccinimide in Acidic Medium Using Iridium(III) Chloride as Inhibitor

2021 ◽  
Vol 34 (1) ◽  
pp. 162-168
Author(s):  
Rakesh Patel ◽  
Ravi Prakash ◽  
Ritu Swamini Bala ◽  
Brijesh Kumar Prajapati ◽  
Rupam Yadav
Keyword(s):  
Activation Energy ◽  
Activation Parameters ◽  
First Order Kinetics ◽  
Free Energy Of Activation ◽  
Enthalpy Of Activation ◽  
Rate Of Reaction ◽  
Entropy Of Activation ◽  
Acidic Conditions ◽  
Kinetic Oxidation

In present study, the kinetics and mechanism of oxidation of pentoxifylline (PTX) by N-chlorosuccinimide (NCS) in acidic conditions at 40 ± 0.1 ºC is reported. The reaction depicts first-order kinetics in regard to [NCS], [PTX] and [HClO4]. The reaction rate goes on decreasing as the concentration of iridium(III) chloride is increased. This shows that iridium(III) chloride plays the role of an inhibitor in the reaction under investigation. Nil impact of [Hg(OAc)2], [NHS] and dielectric constant (D) of the medium on the rate of oxidation of pentoxifylline have been observed. This reaction has been investigated from 308-323 K and the monitored rate of reaction suggests a direct relationship between temperature and the rate of reaction. From the graph between log k and 1/T, value of activation energy (Ea) was numerated and more activation parameters like enthalpy of activation (ΔH#), entropy of activation (ΔS#) and free energy of activation (ΔG#) were calculated with the help of activation energy (Ea). On account of experimentally determined the kinetic orders and activation parameters, a most plausible reaction path has been suggested for the oxidation of pentoxifylline in presence of Ir(III) as an inhibitor.

INTERMOLECULAR FORCES AND LIQUID STRUCTURE IN SOME METAL ALKOXIDES

1961 ◽  
Vol 39 (8) ◽  
pp. 1619-1624 ◽  
Author(s):  
D. C. Bradley ◽  
Calliope C. A. Prevedorou ◽  
W. Wardlaw
Keyword(s):  
Activation Energy ◽  
Free Energy ◽  
Viscous Flow ◽  
Liquid Structure ◽  
Intermolecular Forces ◽  
Metal Alkoxides ◽  
Temperature Range ◽  
Entropy Of Activation ◽  
Titanium Zirconium

The viscosities of some alkoxides of titanium, zirconium, cerium (IV), thorium, and tin (IV) have been measured in the temperature range 25–40 °C. The liquid structure in these compounds is discussed in terms of the activation energy, free energy, and entropy of activation for viscous flow, and the energies of cohesion and vaporization.

A capillary electrophoretic determination of the kinetics of tetradecanedisulfate hydrolysis

1999 ◽  
Vol 77 (2) ◽  
pp. 227-231 ◽  
Author(s):  
Richard A Walker ◽  
D Gerrard Marangoni ◽  
Truis Smith-Palmer
Keyword(s):  
Activation Energy ◽  
Capillary Electrophoresis ◽  
Sulfuric Acid ◽  
Acid Solution ◽  
Acid Hydrolysis ◽  
First Order ◽  
Entropy Of Activation ◽  
Capillary Electrophoretic ◽  
Kinetics Of

Capillary electrophoresis was used to follow the decrease in concentration of tetradecanedisulfate as a function of time during its hydrolysis in 0.5 M sulfuric acid solution at 60, 75, and 90°C. The hydrolyses were mostly carried out at premicellar concentrations of surfactant, from 1 to 7.5 mM. Large increases of rate occurred at higher concentrations (at least 15 mM). The reaction was found to be first order in tetradecanedisulfate. The activation energy and entropy of activation were calculated to be 97 kJ mol-1 and -55 J K-1 mol-1, respectively.Key words: capillary electrophoresis, surfactant, acid hydrolysis, tetradecanedisulfate, activation energy, entropy of activation.

Chemistry of gaseous ion pairs produced by thermal collisions

1980 ◽  
Vol 77 ◽  
pp. 759-768 ◽  
Author(s):  
R. Stephen Berry
Keyword(s):  
Ion Pairs

High Temperature n- and p-type Doped Microcrystalline Silicon Layers Grown by VHF PECVD Layer-by-Layer Deposition

2003 ◽  
Vol 762 ◽  
Author(s):  
A. Gordijn ◽  
J.K. Rath ◽  
R.E.I. Schropp
Keyword(s):  
Activation Energy ◽  
High Temperature ◽  
High Temperatures ◽  
Continuous Wave ◽  
Hydrogen Plasma ◽  
Silicon Layer ◽  
Dark Conductivity ◽  
High Deposition Rate ◽  
Layer By Layer ◽  
Microcrystalline Silicon

AbstractDue to the high temperatures used for high deposition rate microcrystalline (μc-Si:H) and polycrystalline silicon, there is a need for compact and temperature-stable doped layers. In this study we report on films grown by the layer-by-layer method (LbL) using VHF PECVD. Growth of an amorphous silicon layer is alternated by a hydrogen plasma treatment. In LbL, the surface reactions are separated time-wise from the nucleation in the bulk. We observed that it is possible to incorporate dopant atoms in the layer, without disturbing the nucleation. Even at high substrate temperatures (up to 400°C) doped layers can be made microcrystalline. At these temperatures, in the continuous wave case, crystallinity is hindered, which is generally attributed to the out-diffusion of hydrogen from the surface and the presence of impurities (dopants).We observe that the parameter window for the treatment time for p-layers is smaller compared to n-layers. Moreover we observe that for high temperatures, the nucleation of p-layers is more adversely affected than for n-layers. Thin, doped layers have been structurally, optically and electrically characterized. The best n-layer made at 400°C, with a thickness of only 31 nm, had an activation energy of 0.056 eV and a dark conductivity of 2.7 S/cm, while the best p-layer made at 350°C, with a thickness of 29 nm, had an activation energy of 0.11 V and a dark conductivity of 0.1 S/cm. The suitability of these high temperature n-layers has been demonstrated in an n-i-p microcrystalline silicon solar cell with an unoptimized μc-Si:H i-layer deposited at 250°C and without buffer. The Voc of the cell is 0.48 V and the fill factor is 70 %.

White- and Brown-Rice Supplementation Improves Insulin Tolerance, Brown Fat Activation, Energy Expenditure, and Changes the Gut Microflora in Diet-Induced Obesity

Diabetes ◽  
2018 ◽  
Vol 67 (Supplement 1) ◽  
pp. 1897-P
Author(s):  
HISASHI YOKOMIZO ◽  
ATSUSHI ISHIKADO ◽  
TAKANORI SHINJO ◽  
KYOUNGMIN PARK ◽  
YASUTAKA MAEDA ◽  
...  
Keyword(s):  
Activation Energy ◽  
Energy Expenditure ◽  
Brown Rice ◽  
Brown Fat ◽  
Gut Microflora ◽  
Diet Induced Obesity ◽  
Insulin Tolerance

Activation energy of relaxation processes in chalcogenide glasses

2013 ◽  
Vol 34 (0) ◽  
pp. 59-63
Author(s):  
А. А. Горват ◽  
В. М. Кришеник ◽  
А. Е. Кріштофорій ◽  
В. В. Мінькович ◽  
О. А. Молнар
Keyword(s):  
Activation Energy ◽  
Chalcogenide Glasses ◽  
Relaxation Processes
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