Catalysts speed up reactions by lowering activation energy

Steps:

• Identify the reaction as an equilibrium: 2SO₂ + O₂ ⇌ 2SO₃ in the Contact process.
• Recall that catalysts provide an alternative pathway for the reaction without being consumed.
• Determine the catalyst's role: it affects rate, not position of equilibrium.
• Match to options: only lowering activation energy fits the definition.

Why A is correct:

• Catalysts lower the activation energy (E_a), the minimum energy needed for reactants to form products, speeding up the rate as per the Arrhenius equation: rate constant k = A e^(-E_a/RT).

Why the others are wrong:

• B: The catalyst (V₂O₅) facilitates oxidation but does not directly oxidize SO₂ itself.
• C: The reaction oxidizes SO₂ to SO₃; reduction would produce SO₂, opposite of the process.
• D: Catalysts increase rates of both forward and reverse reactions equally, so equilibrium position (K_c) remains unchanged.

Final answer: A