Chemistry Reaction Kinetics ETEA 2023
PMDC Verified Question 19 of 80
As compared to exothermic reaction, formation of activated complex in endothermic reaction requires:
A
Greater Ea
B
Smaller Ea
C
Equal Ea
D
No Ea
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option A: Greater Ea
Concept:

Activation energy (\( E_a \)) is the energy difference between the reactants and the transition state (activated complex).

Solution:

  • In an endothermic reaction, the products have a higher potential energy than the reactants, and a large amount of energy must be absorbed to break the strong initial bonds.
  • Because the reactants sit at a much lower energy well relative to the transition state, the "energy hill" they must climb is significantly steeper.
  • Therefore, endothermic reactions typically require a greater activation energy (\( E_a \)) compared to exothermic reactions, where the reactants are inherently closer to the transition state energy.


Why other options are incorrect:

If it required smaller or equal \( E_a \), it would likely not be heavily endothermic. All standard reactions require some \( E_a \).

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