Energy of Activation, E a(Arrhenius Energy of Activation; Activation Energy)

2016 ◽  
Author(s):  
Victor Gold
Keyword(s):  
Activation Energy ◽  
Energy Of Activation ◽  
Arrhenius Energy

Thermal Degradation of Complexes Derived from Cu (II) Groundnut (Arachis hypogaea) and Sesame (Sesamum indicum) Soaps

2018 ◽  
Vol 0 (0) ◽  
Author(s):  
Anju Joram ◽  
Rashmi Sharma ◽  
Arun kumar Sharma
Keyword(s):  
Activation Energy ◽  
Fatty Acid ◽  
Thermal Degradation ◽  
Arachis Hypogaea ◽  
Edible Oils ◽  
Analytical Data ◽  
Spectroscopic Technique ◽  
Sesamum Indicum ◽  
Energy Of Activation ◽  
Significant Information

Abstract The complexes have been synthesized from Cu (II) soaps of groundnut (Arachis hypogaea) and sesame (Sesamum indicum) oils, with ligand containing nitrogen and sulfur atoms like 2-amino-6-methyl benzothiazole. The complexes were greenish brown in color. In order to study TGA, first characterized them by elemental analysis, and spectroscopic technique such as IR, NMR and ESR. From the analytical data, the stoichiometry’s of the complexes have been observed to be 1:1 (metal:ligand). These complexes have been thermally analyzed using TGA techniques to determine their energy of activation. These complexes show three step thermal degradation corresponding to fatty acid components of the edible oils and each complex has three decomposition steps in the range of 439–738 K. Various equations like Coats–Redfern (CR), Horowitz–Metzger (HM) and Broido equations (BE) were applied to evaluate the energy of activation. The values of energy of activation are observed to be in the following order for both copper groundnut benzothiazole (CGB) and copper sesame benzothiazole (CSeB) complexes: CGB > CSeB. CGB is observed to be more stable than CSeB due to its higher activation energy. The above studies would provide significant information regarding the applications of synthesized agrochemicals and their safe removal through parameters obtained in degradation curves and its relation with energy.

A NOTE ON THE ENERGY OF ACTIVATION OF THE AMYLASE IN VARIOUS HUMAN BODY FLUIDS

1956 ◽  
Vol 34 (1) ◽  
pp. 6-9 ◽  
Author(s):  
Leslie Kovacs ◽  
Jules Tuba
Keyword(s):  
Activation Energy ◽  
Human Body ◽  
Mean Value ◽  
Body Fluids ◽  
Normal Serum ◽  
The Body ◽  
Energy Of Activation ◽  
Heat Inactivation ◽  
Head Of The Pancreas ◽  
The Mean

The activation energy was determined for the amylase present in the following fluids obtained from the human body: urine, duodenal fluid, saliva, and normal serum, as well as serum from patients with mumps, acute pancreatitis, and carcinoma of the head of the pancreas. Over a temperature range of 4°–37.4 °C., with starch as a substrate, the value of the energy of activation was similar in all cases to that for bacterial α-amylase, and the mean value was 13,740 ± 200 cal./mole. Partial heat inactivation of the enzyme was evident in some cases at 37.4°. On the basis of the evidence obtained it appears that α-amylase is present in all the body fluids examined.

scholarly journals A theory of electro-kinetic effects in solution; reactions between ions and polar molecules

1936 ◽  
Vol 157 (892) ◽  
pp. 667-679 ◽  
Keyword(s):  
Maximum Velocity ◽  
Energy Of Activation ◽  
Theoretical Expression ◽  
Bimolecular Reactions ◽  
Sufficient Energy ◽  
Absolute Probability ◽  
Kinetic Effects ◽  
Arrhenius Energy ◽  
Experimental Values ◽  
True Energy

The experimental values of the velocity coefficient k for bimolecular reactions may be summarized in an equation of the form k = Z . P . e -E A /RT (1) where P and E A are empirical constants, specific for each reacting system, and Z is the kinetic theory value for the frequency of binary collisions, namely, Z = N 0 /1000 r 1,2 2 n 1 n 2 { 8π k T (1/m 1 + 1/m 2 )}. (2) The physical significance of the term P may be realized by considering the hypothetical case where the Arrhenius energy of activation E A is identical with the true energy of activation E'. Since the theoretical expression for the maximum velocity of the bimolecular process is k = Z . e -E'/RT , (3) it is seen that P measures the absolute probability that a binary collision of sufficient energy leads to chemical reaction. In general, however, E A and E' are not identical, and the interpretation of the term P is not so simple.

Influence of Specific Absorbed Microwave Power on Activation Energy of Densification in Ceramic Materials

1996 ◽  
Vol 430 ◽  
Author(s):  
Y. Bykov ◽  
A. Eremeev ◽  
V. Holoptsev
Keyword(s):  
Activation Energy ◽  
Silicon Nitride ◽  
Energy Balance ◽  
Experimental Method ◽  
Microwave Power ◽  
Ceramic Materials ◽  
Energy Of Activation ◽  
Initial Stage ◽  
Microwave Furnace ◽  
Apparent Energy Of Activation

AbstractCorrelation between the rate of densification in powder ceramic materials and specific absorbed microwave power is determined by the experimental method. The approach is based on a comparison of the densification curves obtained at different rates of heating. The changes in the ramping rate are provided by varying the microwave power fed into the microwave furnace. Using the energy balance for the microwave heated samples, the correlation between the apparent energy of activation at the initial stage of densification and the value of the specific microwave power absorbed in heated materials are found. The experiments with silicon nitride-based ceramics allowed to determine the reduction in the value of the activation energy resulted from an increase in the specific absorbed microwave power.

DIFFUSION PHENOMENA AND ISOTOPE EFFECTS IN THE EXTRACTION OF FISSION-PRODUCT XENON AND KRYPTON FROM IRRADIATED U3O8

1960 ◽  
Vol 38 (7) ◽  
pp. 945-954 ◽  
Author(s):  
T. J. Kennett ◽  
H. G. Thode
Keyword(s):  
Activation Energy ◽  
Fission Product ◽  
Isotope Effects ◽  
Isotopic Fractionation ◽  
Low Energy ◽  
Energy Of Activation ◽  
Diffusion Phenomena ◽  
Fission Yields

An investigation of the diffusion of fission-product xenon and krypton from irradiated U3O8 powder as a function of temperature has revealed isotopic fractionation and also a double-valued activation energy. The apparent fission yields of Xe131 and Xe132 show abnormal enrichments of up to a factor of 10. These enrichments appear to be related to the precursor half-lives of xenon. When isotopic fractionation exists, the diffusion results exhibit an extremely low energy of activation.

scholarly journals Enzymatic Kinetic Issues and Controversies Surrounding Gibbs Free Energy of Activation and Arrhenius Activation Energy

2020 ◽  
pp. 1-13
Author(s):  
Ikechukwu I. Udema ◽  
Abraham Olalere Onigbinde
Keyword(s):  
Activation Energy ◽  
Free Energy ◽  
Equilibrium Constant ◽  
Gibbs Free Energy ◽  
Theoretical Research ◽  
Energy Of Activation ◽  
Arrhenius Activation Energy ◽  
Free Energy Of Activation ◽  
Different Temperatures ◽  
The Difference

Background: The equation of the difference between reverse and forward Gibbs free energy of activation (ΔΔGES#) reflects Michaelis-Menten constant (KM) in both directions; this may not be applicable to all enzymes even if the reverse reaction is speculatively Michaelian. Arrhenius activation energy, Ea and (Ea - ΔGES#)/RT) are considered = ΔGES# and KM respectively. The equations are considered unlikely. Objectives: The objectives of this research are: 1) To derive what is considered as an appropriate equation for the determination of the difference in ΔGES# between the reverse and forward directions, 2) calculate the difference between the reverse and total forward ΔGES#, and 3) show reasons why Ea ≠ ΔGES#  in all cases. Methods: A major theoretical research and experimentation using Bernfeld method. Results and Discussion: A dimensionless equilibrium constant KES is given. Expectedly, the rate constants were higher at higher temperatures and the free energy of activation with salt was < the Arrhenius activation energy, Ea; ΔΔGES#ranges between 67 - 68 kJ/mol. Conclusion: The equations for the calculation of the difference in free energy of activation (ΔΔGES#) between the forward and reverse directions and a dimensionless equilibrium constant for the formation of enzyme-substrate (ES) were derivable. The large positive value of the ΔΔGES# shows that the forward reaction is not substantially spontaneous; this is due perhaps, to the nature of substrate. The equality of Arrhenius activation energy (Ea) and ΔGES# may not be ruled out completely but it must not always be the case; the presence of additive like salt can increase the magnitude of Ea well above the values of the ΔGES#. A dimensionless equilibrium constant for the net yield of ES seems to be a better alternative than KM. The Ea unlike ΔGES#  requires at least two different temperatures for its calculation.

scholarly journals Arrhenius-Type Relationship of Viscosity as a Function of Temperature for Mustard and Cotton Seed Oils

2020 ◽  
Vol 3 (3b) ◽  
pp. 144-155
Author(s):  
E Ike
Keyword(s):  
Activation Energy ◽  
Cotton Seed ◽  
Seed Oil ◽  
Mustard Oil ◽  
Seed Oils ◽  
Activation Temperature ◽  
Exponential Factor ◽  
Arrhenius Energy ◽  
Arrhenius Temperature ◽  
Cotton Seed Oil

The knowledge and estimate of transport behaviours of fluids are very influential in heat and mass flow. In this study, an equation correlating the Arrhenius energy (Ea), the pre-exponential factor (A), the Arrhenius temperature (T) and the Arrhenius activation temperature (T*) is applied so as to buttress the depth of discussion. The results obtained from the viscosity experiments of Mustard and Cotton seed oils at different temperature ranges offers very good results statistically. The Activation energy Ea, Entropic (pre-exponential) factor A, Arrhenius temperature TA and the Arrhenius activation temperature for the mustard oil were observed to be 374.37381 J/mole, 12.39260595 cP, -17.89797783 oC, 45.051 oC respectively while Activation energy Ea, Entropic (pre-exponential) factor A, Arrhenius temperature TA and the Arrhenius activation temperature for the cotton seed oil are respectively 451.90611 J/mole, 8.210386507 cP, - 25.8292961 oC, 54.381 oC. The coefficients of regressions (R2) for the graph of the natural log of viscosity versus reciprocal of temperature (Figures 2 and 4) for the mustard oil and cotton seed oil are 0.9996 and 0.9996 respectively. Since the correlation coefficient is the measure of how well a collection of data points can be modeled by a line, we can hence conclude that the natural log of the viscosity of both seed oil samples versus the inverse of their respective temperatures have a very good fit.

Determining the energy of activation for the formation of lactulose in heated milks

1985 ◽  
Vol 52 (2) ◽  
pp. 275-280 ◽  
Author(s):  
Geoffrey R. Andrews
Keyword(s):  
Activation Energy ◽  
High Temperature ◽  
Temperature Profile ◽  
Energy Of Activation ◽  
Temperature Profiles ◽  
Milk Processing ◽  
Arrhenius Relationship ◽  
Processing Plants ◽  
Sterilized Milk ◽  
Ultra High Temperature

SUMMARYTime/temperature profiles were obtained for commercial ultra high temperature (UHT) and sterilized milk processing plants and for a pilot UHT plant operating under nine different conditions. Samples of milk from each process were analysed for lactulose by an enzymic method, yielding concentrations of lactulose of 4 to 118 mg/100 ml. The measured lactulose concentration could be derived from the corresponding time/temperature profile by assuming an Arrhenius relationship with an activation energy of 152 kJ mol-1, for the whole range of UHT and in-container processes examined.

A NOTE ON THE ENERGY OF ACTIVATION OF THE AMYLASE IN VARIOUS HUMAN BODY FLUIDS

1956 ◽  
Vol 34 (1) ◽  
pp. 6-9 ◽  
Author(s):  
Leslie Kovacs ◽  
Jules Tuba
Keyword(s):  
Activation Energy ◽  
Human Body ◽  
Mean Value ◽  
Body Fluids ◽  
Normal Serum ◽  
The Body ◽  
Energy Of Activation ◽  
Heat Inactivation ◽  
Head Of The Pancreas ◽  
The Mean

The activation energy was determined for the amylase present in the following fluids obtained from the human body: urine, duodenal fluid, saliva, and normal serum, as well as serum from patients with mumps, acute pancreatitis, and carcinoma of the head of the pancreas. Over a temperature range of 4°–37.4 °C., with starch as a substrate, the value of the energy of activation was similar in all cases to that for bacterial α-amylase, and the mean value was 13,740 ± 200 cal./mole. Partial heat inactivation of the enzyme was evident in some cases at 37.4°. On the basis of the evidence obtained it appears that α-amylase is present in all the body fluids examined.

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