In the reaction between silver nitrate and sodium chloride, what happens to the sodium ions (Na+) after the reaction?

• A. They precipitate as solid Na2O.
• B. They are reduced to metallic sodium.
• C. They remain in solution as spectator ions.
• D. They form sodium sulfate.

Answer: (C)

When ionic compounds react in solution, a precipitate forms from the ions that combine to make an insoluble solid, while the other ions remain dissolved as spectator ions. Here, Ag+ from silver nitrate and Cl− from sodium chloride come together to form insoluble silver chloride (the precipitate). The sodium ions do not take part in forming a solid or in any redox change; they stay in the solution as Na+ (paired with NO3− as NaNO3), so they remain as dissolved ions. That’s why the sodium ions are considered spectator ions.