Question

An endothermic reaction, A$\to$ B has an activation energy 15 kcal/mol and energy of the reaction is 5 kcal/mol. The activation energy of the reaction, B $\to$ A is:

• A. 20 kcal/mol
• B. 15 kcal/mol
• C. 10 kcal/mol
• D. 5 kcal/mol

Answer 1

Answer: (C)

10 kcal/mol

For an endothermic reaction, the activation energy for the backward reaction is equal to the difference of the activation energy of the forward reaction and the enthalpy change of the reaction.

Thus, the activation energy of the reaction $B\to A$ is $15-5=10kcal.$