Acids & Bases
What You’ll Learn
The common ion effect refers to the decrease in solubility of an ionic compound when a compound containing one of its ions is added to the solution. It occurs because the added ions shift the equilibrium towards the solid state, causing more precipitation of the ionic compound. The common ion effect is a consequence of Le Chatelier's principle, where the system adjusts to counteract the stress of added ions. It is observed in solubility equilibria involving slightly soluble salts and weak acids/bases.