Question

Which one of the following is true for an exothermic reaction $A \rightleftharpoons B$, if $E_{f}$ and $E_{b}$ are the activation energies of forward and backward reactions respectively?

• A. $E_{f} > E_{b}$
• B. $E_{f}=E_{b}$
• C. $E_{f}=-E_{b}$
• D. $E_{f} < E_{b}$

Answer 1

Answer: (D)

Activation energy for the forward reaction, $E_{f}$ and the activation energy for the backward reaction, $E_{b}$ are related to the enthalpy of the reaction by the equation.

$\Delta_{r} H=E_{f}-E_{b}$

For exothermic reaction

$\Delta_{r} H < 0 $

$E_{b} > E_{f}$