Explain why spectator ions such as sodium and chloride do not affect the pH of an aqueous salt solution. Include a discussion of reactivity in your explanation.

Question

Explain why spectator ions such as sodium and chloride do not affect the pH of an aqueous salt solution. Include a discussion of reactivity in your explanation.

Answer 1

By definition, spectator ions appear on both sides of the balanced chemical equation. They do NOT take part in the chemical reaction. Therefore, they will not affect the pH of the solution.

There really is no discussion of reactivity since the spectator ions appear on both sides of the equation, they cancel each other out. So it matters little if they are very reactive, or not so much. It also matters little if they are from acid or basic salts. They simply do NOT enter into the reaction.

If you are talking about ions of an aqueous salt solution, and not necessarily spectator ions, then we have a different story. Na⁺ and Cl^- will be neutral, but Na⁺ and C₂H₃O₂^- (acetate) will be basic. NH₄⁺ and Cl^- will be acidic. This, however, is a completely different discussion and not related to spectator ions.

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