Question

$N_2\left(g\right)+3H_2\left(g\right)\rightleftharpoons 2N{H}_3\left(g\right)+22$ kcal. The activation energy for the forward reaction $50$ kcal. What is the activation energy for the backward reaction?

• A. $72$ kcal
• B. $28$ kcal
• C. $-72$ kcal
• D. $-28$ kcal

Answer 1

The correct option is A $72$ kcal

$N_2\left(g\right)+3H_2\left(g\right)\rightleftharpoons 2N{H}_3\left(g\right)+22$ kcal

$\Rightarrow \Delta H=-22kcal$

$\because$ Activation energy for the forward reaction $E_a=50$ kcal

$\therefore$ Activation energy for the backward reaction $E_b=E_a-\Delta H=50+22=72$ kcal.