energy of activation


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energy of activation

[′en·ər·jē əv ak·tə′vā·shən]
(physical chemistry)
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where [E.sub.a] is the energy of activation, R denotes the universal gas constant, [T.sub.c] is the crystallization peak temperature at which reaction rate reaches maximum and [psi] is the cooling rate.
The values of the effective diffusion coefficient as function of temperature and pressure are between 1.95 x [10.sup.-10] and 2.11 x [10.sup.-9] [m.sup.2]/h; the energy of activation [107.96-123.70 kJ/mol] and the distribution coefficient [0.03-2.17] suggest that this is a difficult operation and high energy-demanding process.
The free energy change ([DELTA]G), enthalpy change ([DELTA]H), entropy change ([DELTA]S) and energy of activation ([E.sub.a]) for the lipase catalyzed reaction were found to be -23.2 kJ [mol.sup.-1], 15.9 kJ [mol.sup.-1], 124.7 J [K.sup.-1] [mol.sup.-1] and 19.1 kJ [mol.sup.-1], respectively.
The energy of activated molecules is a kind of triplet consisting mostly of three components: activation enthalpy, activation entropy and free energy of activation [8, 22].
(viii) The various kinetic parameters like energy of activation ([E.sub.a]), frequency factor (Z), and entropy of decomposition ([DELTA][S.sup.*]) using three different equations were calculated for all the three stages of decomposition, indicating that minimum activation energy is required to break the molecules in the first stage of decomposition because the water molecules are loosely bound to the mixed crystal.
Mixtures of AN +3- HPN have great affinity to dissolve the alkali metal electrolytes because 3-HPN is a protic solvent and has great solubility property towards electrolytes [12].The aim of this work is to report the experimental data of densities and viscosities of alkali metal bromides in AN, 3-HPN and in a 50% AN +3-HPN mixture at different temperatures to determine the activation and thermodynamic parameters like energy of activation 6Ev , Gibbs energy change 6G and entropychange 6S .
The Arrhenius plot to calculate energy of activation for thermal denaturation (Ea) is shown in Fig.
* Increasing accelerator loading or changing to an ultra accelerator for sulfur cures can increase the energy of activation ([E.sub.a]).
The effect of chemically stable surface active inhibitors is to increase the energy of activation and to decrease the surface area available for corrosion (30) The results in Table 3 indicate that the value of activation energy ([E.sub.a]) in 0.5 M NaOH solution containing inhibitor is greater than that without the inhibitor.
Energy of activation and other activation parameters observed for the oxidation of D-arabinose and D-xylose at 40[degrees]C.
In first step, energy of activation (E) is maximum for HAS-6 and minimum for HAS-2.