What is the net ionic equation for the reaction between MgCl_2 and NaOH in aqueous solution?

• A. Mg^{2+} (aq) + 2Cl^{-} (aq) + 2Na^{+} (aq) + 2OH^{-} (aq) → Mg^{2+} (aq) + 2Cl^{-} (aq) + 2Na^{+} (aq) + 2OH^{-} (aq)
• B. MgCl_2 (aq) + 2NaOH (aq) → Mg(OH)_2 (s) + 2NaCl (aq)
• C. Mg(OH)_2 (aq) + 2NaCl (aq) → MgCl_2 (aq) + 2NaOH (aq)
• D. Mg^{2+} (aq) + 2OH^{-} (aq) → Mg(OH)_2 (s)

Answer: (D)

Verified step by step guidance

1. Write the balanced molecular equation for the reaction between magnesium chloride and sodium hydroxide: \(\mathrm{MgCl_2 (aq) + 2NaOH (aq) \rightarrow Mg(OH)_2 (s) + 2NaCl (aq)}\).
2. Dissociate all strong electrolytes (soluble salts and strong bases) into their ions to write the complete ionic equation: \(\mathrm{Mg^{2+} (aq) + 2Cl^{-} (aq) + 2Na^{+} (aq) + 2OH^{-} (aq) \rightarrow Mg(OH)_2 (s) + 2Na^{+} (aq) + 2Cl^{-} (aq)}\).
3. Identify the spectator ions, which are ions that appear unchanged on both sides of the equation. Here, \(\mathrm{Na^{+}}\) and \(\mathrm{Cl^{-}}\) are spectator ions.
4. Remove the spectator ions from the complete ionic equation to write the net ionic equation: \(\mathrm{Mg^{2+} (aq) + 2OH^{-} (aq) \rightarrow Mg(OH)_2 (s)}\).
5. Confirm that the net ionic equation shows the formation of the solid precipitate magnesium hydroxide from its ions in solution, which is the key chemical change in this reaction.