Question

An exothermic chemical process occurs in two steps as follows:
(i) $A+B\to X$ (slow)
(ii) $X\to AB$ (fast)
The energy profile diagram that best suits this process is:

• A.
• B.
• C.
• D.

Answer 1

The correct option is C

The given reaction is exothermic, which indicates that the energy of the product should be lower than the energy of the reactants.
In option (d), the energy of the product is higher than the reactants, hence it is incorrect. Since the reaction follows two step process, thus the option (B) also cannot be true.
According to the question the first step of the reaction is the slowest step. thus its activation energy will be more than that of the second step. Which lead us to the correct option i.e. (C)