Activation Energy in Reversible Reactions

Steps:

• Recall activation energy (Ea) is the minimum energy required for effective collisions to form products.
• Note catalysts like iron lower Ea for both forward and reverse reactions equally in equilibrium systems.
• Compare Ea for forward (higher) and reverse (lower by ΔH) reactions in exothermic Haber process.
• Evaluate statements: A mismatches Ea values; B and D ignore equal catalyst effect; C matches definition.

Why C is correct:

• Activation energy is defined as the minimum kinetic energy colliding particles need to overcome the energy barrier and react, per collision theory.

Why the others are wrong:

• A: Ea forward exceeds Ea reverse by the exothermic reaction's enthalpy change (ΔH < 0).
• B: Iron catalyst reduces Ea for both directions equally, not just forward.
• D: Iron decreases Ea for reverse reaction equally with forward, maintaining equilibrium.

Final answer: C