Question:
An exothermic reaction $X \rightarrow Y$ has an activation energy $30 \mathrm{~kJ} \mathrm{~mol}^{-1}$. If energy change $\Delta \mathrm{E}$ during the reaction is $-20 \mathrm{~kJ}$, then the activation energy for the reverse reaction in $\mathrm{kJ}$ is______.
Solution:
$\mathrm{X} \longrightarrow \mathrm{Y}$
