The effective activation energy for the reaction:

with the following potential energy versus reaction coordinate plot is

Concept:-

Activation energy:

• ​It is the least amount of additional energy that a reacting molecule needs to produce a reaction product.
• It is often referred to as the minimum energy needed to energise or activate molecules or atoms so that they can engage in a chemical reaction or transformation.
• The addition of a catalyst during a chemical reaction alters activation energy.​
  • The presence of a catalyst lowers the activation energy of any reaction, hence it speeds up the rate of reaction. 
  • ​The catalyst provides an alternate pathway of lower activation energy.
• ​It is measured in joules (J) and or kilojoules per mole (kJ/mol) or kilocalories per mole (kcal/mol).
• It is denoted by Ea.

Explanation:-

• The reaction is given by,

with the following potential energy versus reaction coordinate plot is

• The effective activation energy for the reaction will be,

= Ea + Eb - Ea'

Conclusion:-

Hence, the effective activation energy for the reaction with the following potential energy versus reaction coordinate plot is

Ea + Eb - Ea'