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Environmental factors and testing
Published in Stephen Sangwine, Electronic Components and Technology, 2018
A second, very significant effect of temperature on reliability is an increase in the rate of component ageing or deterioration with increased temperature. Many component wear-out failures are caused by chemical reactions occurring inside the component, and because the rate of reaction increases with temperature, the life of a component is reduced by operating at higher temperatures. Many chemical reactions obey the Arrhenius equation () λ= K exp(-E/kt)The Arrhenius equation is discussed by O’Connor (2002), and in its chemical context in any “A” level or high school physical chemistry text. O’Connor expressed some doubt as to whether the equation is valid for many electronic components.
Chemical Kinetics
Published in Franco Battaglia, Thomas F. George, Understanding Molecules, 2018
Franco Battaglia, Thomas F. George
We should be aware that Arrhenius equation does not apply to some reactions. For instance, it may occur that the rate constant increases indeed with temperature but, beyond a given temperature, it does so more rapidly than what Arrhenius equation predicts: this is the case, for instance, of chain reactions. Or, it may occur that the rate constant decreases as temperature increases, or that this happens, again, beyond a specific temperature value. This is the case, for instance, if the reactive collision is favored only if the colliding molecules have a precise relative orientation, a circumstance that is the more hindered the higher the temperature. We shall confine ourselves to reactions whose rate constants follow the Arrhenius equation: in particular, we shall be interested in proposing a molecular-level interpretation of both the pre-exponential factor and the activation energy.
Physics of Temperature and Temperature’s Role in Carrier Transport
Published in John D. Cressler, H. Alan Mantooth, Extreme Environment Electronics, 2017
Cressler John D., Moen Kurt A.
Let us now briefly examine the fundamental origins of “thermal activation,” sometimes referred to as “Arrhenius behavior.” The Arrhenius equation is a well-known formula for the temperature dependence of the reaction rate constant, and therefore, the rate of a chemical reaction. The equation was first proposed by the Dutch chemist J.H. van Hoff in 1884, and 5 years later in 1889, the Swedish chemist S. Arrhenius provided a physical justification and interpretation for it. The Arrhenius equation is given by () R=Ae−Ea/kT
Waste bone char-derived adsorbents: characteristics, adsorption mechanism and model approach
Published in Environmental Technology Reviews, 2023
Abarasi Hart, Duduna William Porbeni, Selina Omonmhenle, Ebikapaye Peretomode
h0 is the initial adsorption rate. If the second-order kinetics is applicable, then the plot of t/qt against t in equation (10) should give a linear relationship from which the constants qe and h0 can be determined. It also suggests several mechanisms are involved in the adsorption process. However, in these kinetic models, the adsorbed amount qe changes with temperature (i.e. a thermodynamic equilibrium quantity), so the temperature dependence of the rate constant needs to be accounted for in the models. Hence, the activation energy can also be estimated with the Arrhenius equation and rate constants for various temperatures. Using the Arrhenius equation (11), the activation energy (Ea) and pre-exponential factor (A) of the adsorption process can be determined numerically. Other adsorption kinetics models used to study BC adsorption kinetic include Ritch-second-order, Elovich equation, and intra-particle diffusion model [63], as shown in Table 2. Where; Kads denotes adsorption rate constant, T is temperature (K), and R constant. The plot of ln Kads versus 1/T is linear from which Ea and A would be determined.
A kinetic study and thermal decomposition characteristics of palm kernel shell using model-fitting and model-free methods
Published in Biofuels, 2022
Maham Hussain, Haslinda Zabiri, Lemma Dendena Tufa, Suzana Yusup, Imtiaz Ali
The kinetic parameters calculated from the order-based model of solid-state reactions resulted in significant deviations [14]. Hence, integral methods such as Kissinger-Akahira-Sunose (KAS) [21], and Flynn-Wall-Ozawa (FWO) [22] have been used more in the kinetic analysis of biomass nowadays. The activation energy can be calculated from TG and DTG curve data based on model-free models. Also, an estimation of reaction order is not required to avoid kinetic compensation effects. Therefore, model-free model errors resulting from kinetic analysis through Arrhenius parameter estimations can be avoided [23]. The pre-exponential factor or A factor is the pre-exponential constant in the Arrhenius equation, an empirical relationship between temperature and rate coefficient. It is usually designated by A. Presently; thermal degradation of lignocellulosic biomass is extensively studied using model-free methods.
Acceleration of the thermal decomposition of RDX in microdroplets investigated by aerodynamic thermal breakup droplet ionization mass spectrometry
Published in Aerosol Science and Technology, 2020
Viktor V. Pervukhin, Dmitriy G. Sheven
As a result, we obtained the dependence of the reaction rate constant on temperature (Figure 4b), which increases sharply with temperature as expected. The Arrhenius equation usually describes the relation between the reaction rate constant and temperature for chemical reactions. The formulas are: where is a pre-exponential factor, is a reaction activation energy, is capillary temperature (K), and is universal gas constant (8.314 J mol−1 K−1). Thus, fitting a dependence of on (Figure 4c), one can immediately determine the kinetic parameters of the thermal decomposition reaction ( and ). The obtained values are ≈ 33 kJ mol−1 and ≈ 3.28 × 106 s−1.