Reaction Energy Profile & Catalysis

Energy vs. reaction progress. The hump is the activation energy E_a; the gap between the two plateaus is ΔH. A catalyst lowers E_a (forward AND reverse) but never changes ΔH.

Try: turn the catalyst on — the dashed ghost is the old path; the new peak is lower so BOTH E_a(forward) and E_a(reverse) drop by the same idea, yet the two plateaus (and therefore ΔH) stay put. Energy values are in kJ/mol.