Le Chatelier's Principle for Exothermic Equilibrium

Steps:

• Reaction is exothermic (ΔH < 0), so heat acts as product; decreasing temperature favors forward reaction to produce heat.
• Equilibrium shifts right for exothermic reactions when temperature decreases, increasing K since K = [SO3]^2 / ([SO2]^2 [O2]) and lower T boosts product concentrations.
• Pressure affects position based on moles (4 to 3, shifts right) but not K value.
• Catalysts and concentration changes alter rates or position without changing K.

Why C is correct:

• For exothermic reactions, decreasing temperature shifts equilibrium right (Le Chatelier's principle) and increases K, as van't Hoff equation shows ln K = -ΔH/RT + constant.

Why the others are wrong:

• A: Increases pressure shifts right (fewer gas moles) but K remains unchanged.
• B: Catalyst equilibrates faster with no position shift or K change.
• D: Decreases [SO3], shifting left to restore product, not right.

Final answer: C