Le Chatelier's Principle for Exothermic Equilibrium

Steps:

• Identify the reaction as exothermic (ΔH negative), so heat acts as a product.
• Apply Le Chatelier's principle: the system opposes changes to restore equilibrium.
• Evaluate each option's effect on position: left favors reactants, right favors products.
• Select the change that shifts toward reactants (left).

Why C is correct:

• For exothermic reactions, increasing temperature adds heat (like a product), so equilibrium shifts left to absorb heat, per Le Chatelier's principle.

Why the others are wrong:

• A: Adding O₂ (reactant) shifts equilibrium right to consume it.
• B: Increasing pressure favors the side with fewer gas moles (right, 3 vs. 2), shifting right.
• D: Removing SO₃ (product) shifts equilibrium right to replace it.

Final answer: C