Question
The activation energy for a simple chemical reaction, $$A \to B$$ is $${E_a}$$ in forward direction. The activation energy for reverse reaction
A.
can be less than or more than $${E_a}$$
B.
is always double of $${E_a}$$
C.
is negative of $${E_a}$$
D.
is always less than $${E_a}$$
Answer :
can be less than or more than $${E_a}$$
Solution :
The energy of activation of reverse reaction is less than or more than energy of activation $$\left( {{E_a}} \right)$$ of forward reaction.
$$\therefore \,\,\Delta H = {\left( {{E_a}} \right)_F} - {\left( {{E_a}} \right)_R}$$
Because it depends upon the nature of reaction.
If $${\left( {{E_a}} \right)_F} > {\left( {{E_a}} \right)_R},$$ reaction is endothermic
or $${\left( {{E_a}} \right)_F} < {\left( {{E_a}} \right)_R},$$ reaction is exothermic