Question

In reaction, the potential energy of the reactants is 40 kJ/mol, the potential energy of the products is 10 kJ/mol and the potential energy of the activated complex is 55 kJ/mol. What is the activation energy for the reverse reaction?
A. 45 kJ/mol
B. -30 kJ/mol
C. 15 kJ/mol
D. 35 kJ/mol
E. -55 kJ/mol

Answer 1

For this problem, we should know about the activation energy and its effect on the reactant. The formula of activation energy for both reverse and the forward reaction is different. For reverse reaction, the product energy is subtracted from the energy of the activation complex.

Complete step by step solution:
- In the given question, we have to calculate the activation energy for the reverse reaction i.e. from product to the reactant.
- As we know that the forward reaction is the formation of product form the reactant which is also considered as the forward direction.
- Whereas the reverse reaction is the formation of the reactant from the product which is also considered as the backward direction.
- Now, activation energy is the amount of energy that is given to the reactant species so that the collision between the molecules increases and also the formation of the product takes place easily.
- So, for the reverse reaction, the formula to find the activation will be the subtraction of potential energy of the product from the potential energy of the activated complex.
- Now, it is given that the potential energy of the product is $10$ $kJ/mol$ and the potential energy of the activated complex is $55$ $kJ/mol$.
- So, by putting all the values we will get the activation energy of the reverse reaction i.e.
$\text{55 - 10 = 45 kJ/mol}$

Therefore, option (A) is the correct answer.

Note: In the given question, if we have to calculate the activation energy of the forward reaction then we will subtract the potential energy of the reactant from the potential energy of the activated complex.