Eyring equation


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Eyring equation

[′ī·riŋ i‚kwā·zhən]
(physical chemistry)
An equation, based on statistical mechanics, which gives the specific reaction rate for a chemical reaction in terms of the heat of activation, entropy of activation, the temperature, and various constants.
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Thermodynamic parameters of activation including the enthalpy ([DELTA][H.sup.#]), entropy [DELTA][E.sup.#], and free energy Gibbs [DELTA][G.sup.#] of activation for RBB adsorption kinetics were obtained by applying Eyring equation [41, 42].
The Eyring equation in its thermodynamic version is as follows:
With respect to (18), [k.sub.1] is a rate determining step; therefore, the activation parameters which involve [DELTA][G.sup.[double dagger]], [DELTA][S.sup.[double dagger]], and [DELTA][H.sup.[double dagger]] can be now calculated for the first step (rate determining step, [k.sub.1]), as an elementary reaction, on the basis of Eyring equation (a) of Figure 7(a), Ln([k.sub.1] = [k.sub.ove])/T versus 1/T and also a different linearized form of Eyring equation (b) of Figure 7(b), T x Ln([k.sub.1] = [k.sub.ove])/T against (T) [39].
(5) The activation energy (45.9764 [+ or -] 0.246 kJ x [mol.sup.-1]) and parameters of the reaction involving [DELTA][G.sup.[double dagger]], [DELTA][S.sup.[double dagger]], and [DELTA][H.sup.[double dagger]] have been calculated, on the basis of both Eyring equation and a different linearized form.
The craze growth rates were found to exponentially increase with an increase in stress, obeying the Eyring equation for thermally activated processes In the presence of an applied stress.
The Eyring equation for yield stress shown in Eq 5 will now be fit to the experimental data of Fig.
Although the above concept has often been used to analyze plastic deformation of polymers exhibiting shear yielding, in the case of toughened polystyrene with multiple crazing, the Eyring equation has been successfully applied to characterize the kinetics of irreversible plastic deformation (26).
The Eyring equation has been shown to be valid at high strain rates by many workers (e.g.
The Eyring equation has been introduced, in the earlier treatments, assuming that the reactants are in equilibrium with the activated complexes, meaning that the activation energy (or the activation volume) is time independent, and so is the structure as well (5).
These values were used in the Arrhenius time-temperature conversion, allowing us to calculate an activation energy [Q.sub.[Beta]] close to those found by other authors or calculated from the Eyring equation, reinforcing the Bauwens approach (Table 2).
Thermodynamic parameters was calculated using the Arrhenius as defined [26] and the Eyring equations [27].
Thus, each material is initially reduced to a constitutive model of two Eyring equations, each having three parameters: an activation energy [DELTA]H, an activation volume V* and a reference strain rate [[epsilon].sub.0]: