Question

What is activation energy ?How it is calculated?

Answer 1

Understanding the concept:

• In chemistry, activation energy is the minimal amount of energy needed to bring atoms or molecules into a state where they can go through a chemical reaction.
• The term "activation energy," coined in 1880 by the Swedish scientist Svante Arrhenius, refers to the minimal amount of energy required for a group of chemical reagents to interact and produce a product.

Calculation of activation energy:

• By determining the rate constant k over a variety of temperatures and then applying the Arrhenius Equation.
• One can determine the activation energy of a reaction.
• Equation: $\ln (\mathrm{k}2/\mathrm{k}1)={\mathrm{E}}_{\mathrm{a}}/\mathrm{R}\times (1/\mathrm{T}1-1/\mathrm{T}2)$ can be used to calculate the activation energy.
• ${\mathrm{E}}_{\mathrm{a}}$= the reaction's activation energy in J/mol
• $R=8.3145\mathrm{J}/\mathrm{Kmol}$, the ideal gas constant.
• Absolute temperatures $\mathrm{T}1$ and $\mathrm{T}2$ (in Kelvin)
• The rate constants at$\mathrm{T}1\mathrm{and}\mathrm{T}2\mathrm{are}\mathrm{K}1\mathrm{and}\mathrm{K}2$, respectively.
• By putting all required values in the above equation, we can calculate an activation energy(${\mathrm{E}}_{\mathrm{a}}$).