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In physical chemistry, the Arrhenius equation is a formula for the temperature dependence of reaction rates.The equation was proposed by Svante Arrhenius in 1889, based on the work of Dutch chemist Jacobus Henricus van 't Hoff who had noted in 1884 that the van 't Hoff equation for the temperature dependence of equilibrium constants suggests such a formula for the rates of both forward and ...
In the Arrhenius equation, the term activation energy (Ea) is used to describe the energy required to reach the transition state, and the exponential relationship k = A exp (−Ea/RT) holds. In transition state theory, a more sophisticated model of the relationship between reaction rates and the transition state, a superficially similar ...
Arrhenius plots are often used to analyze the effect of temperature on the rates of chemical reactions. For a single rate-limited thermally activated process, an Arrhenius plot gives a straight line, from which the activation energy and the pre-exponential factor can both be determined.
A was referred to as the frequency factor (now called the pre-exponential coefficient), and E a is regarded as the activation energy. By the early 20th century many had accepted the Arrhenius equation, but the physical interpretation of A and E a remained vague.
The time–temperature shift factor can also be described in terms of the activation energy (E a). By plotting the shift factor a T versus the reciprocal of temperature (in K), the slope of the curve can be interpreted as E a /k, where k is the Boltzmann constant = 8.64x10 −5 eV/K and the activation energy is expressed in terms of eV.
While in atomic solids transport is intra -molecular, also known as band transport, in molecular solids the transport is inter -molecular, also known as hopping transport. The two different mechanisms result in different charge mobilities. In disordered solids, disordered potentials result in weak localization effects (traps), which reduce the ...
The activation energy is often predicted using the Transition state theory. Increasing the concentration of the reactant brings about more collisions and hence more successful collisions. Increasing the temperature increases the average kinetic energy of the molecules in a solution, increasing the number of collisions that have enough energy.
Different checkpoints for different temperatures can be calculated by using the Arrhenius equation. For example, with an activation energy of 0.7e V, T j of 135 °C and T use of 55 °C the equivalent checkpoints will be at 29, 102, 303 and 606 hours. Electrical testing should be completed as soon as possible after the samples are removed.