Question

Is that possible to have zero activation energy in a reaction? Explain why?

Answer 1

Activation energy:

• Activation energy is defined as the minimum amount of extra energy required by a reacting molecule to get converted into a product.
• Activation energy is denoted by $\mathrm{Ea}$. It is usually measured in joules$\left(\mathrm{J}\right)$ and or kilojoules per mole$(\mathrm{kJ}{\mathrm{mol}}^{-1})$ or kilocalories per mole$(\mathrm{kcal}{\mathrm{mol}}^{-1})$.
• The formula(Arrhenius equation) used to find the value of Activation Energy, $\mathrm{Ea}$ is $K=A{e}^{-\raisebox{1ex}{$Ea$}\!\left/ \!\raisebox{-1ex}{$RT$}\right.}$ ,where $\mathrm{K}$ represents the rate constant, $\mathrm{A}$ represents the pre-exponential factor, $\mathrm{Ea}$ represents the energy of activation, $\mathrm{R}$ represents the gas constant, and $\mathrm{T}$ represents the temperature (in Kelvin)
• Let $\mathrm{Ea}=0$, Then based on the Arrhenius equation,

$$\begin{gathered} K=A{e}^{\raisebox{1ex}{$0$}\!\left/ \!\raisebox{-1ex}{$RT$}\right.} \\ K=A{e}^0 \\ K=A \end{gathered}$$

• Here, $\mathrm{K}=\mathrm{A}$ means that every collision could lead to a chemical reaction that is not possible.

Therefore, a chemical reaction could not have zero energy of activation.