Net Ionic Equation . When a solution of barium chloride, BaCl_{2} , is added to a solution of sodium sulfate, Na_{2} SO_{4} , a white precipitate of barium sulfate, BaSO_{4} , forms. Write the net ionic equation for this reaction.
Strategy : The net ionic equation shows only those ions that combine to form a precipitate.
Because both barium chloride and sodium sulfate are ionic compounds, each exists in water as its dissociated ions:
Ba^{2+} (aq)+ 2Cl^{-} (aq)+2Na^{+} +SO_{4}^{2-} (aq)
We are told that a precipitate of barium sulfate forms:
Because Na^{+} and Cl^{-} ions appear on both sides of the equation (they are spectator ions), we cancel them and are left with the following net ionic
equation:
Net ionic equation: Ba^{2+} (aq) +SO_{4}^{2-} \longrightarrow BaSO_{4} (s)