The equilibrium CaCO₃(s) ⇌ CaO(s) + CO₂(g) is established in a closed container. What happens when the container volume is suddenly decreased at constant temperature?

Core Concept

Shrinking the volume raises the partial pressure of CO₂, the only gaseous species present. The system answers by consuming gas molecules, which means shifting left toward the solid reactants. As CO₂ reacts away, the quotient relaxes back down to Kp. Because temperature never changed, the constant itself holds firm throughout.