Which of the following is the complete ionic equation for the reaction between HCl(aq) and NaOH(aq)?

• A. Na^+(aq) + Cl^-(aq) → NaCl(aq)
• B. HCl(aq) + NaOH(aq) → NaCl(aq) + H_2O(l)
• C. H^+(aq) + Cl^-(aq) + Na^+(aq) + OH^-(aq) → Na^+(aq) + Cl^-(aq) + H_2O(l)
• D. H^+(aq) + OH^-(aq) → H_2O(l)

Answer: (C)

Verified step by step guidance

1. Identify the reactants and products in the given reaction: HCl(aq) and NaOH(aq) react to form NaCl(aq) and H_2O(l).
2. Write the molecular equation showing all reactants and products in their complete formulas: \(\mathrm{HCl(aq) + NaOH(aq) \rightarrow NaCl(aq) + H_2O(l)}\).
3. Break down all strong electrolytes (soluble ionic compounds and strong acids/bases) into their constituent ions to write the complete ionic equation. For example, \(\mathrm{HCl(aq)}\) dissociates into \(\mathrm{H^+(aq)}\) and \(\mathrm{Cl^-(aq)}\), and \(\mathrm{NaOH(aq)}\) dissociates into \(\mathrm{Na^+(aq)}\) and \(\mathrm{OH^-(aq)}\).
4. Write the complete ionic equation by listing all ions present on both sides of the reaction: \(\mathrm{H^+(aq) + Cl^-(aq) + Na^+(aq) + OH^-(aq) \rightarrow Na^+(aq) + Cl^-(aq) + H_2O(l)}\).
5. Recognize the spectator ions (ions that appear unchanged on both sides), which are \(\mathrm{Na^+(aq)}\) and \(\mathrm{Cl^-(aq)}\), and note that the net ionic equation involves only \(\mathrm{H^+(aq)}\) and \(\mathrm{OH^-(aq)}\) forming \(\mathrm{H_2O(l)}\).