Answer;
Soluble metal salt and carbon dioxide
Explanation;
Both soluble metal salt and carbon dioxide may react with a base to form a solid or what we call a precipitate.
- For instance when carbon dioxide is bubbled through a solution of calcium hydroxide, it results to the formation or precipitate calcium carbonate.
Ca(OH)₂(aq) + CO₂(g) → CaCO₃(s) + H₂O(l)
- For the case of a soluble metal salt; an example is calcium nitrate, which is a soluble metal salt, when reacted with a base like sodium hydroxide, it results to the formation of a solid calcium hydroxide and sodium nitrate, a reaction called precipitation reaction.
Ca(NO₃)₂(aq) + NaOH (aq)→ Ca(OH)₂(s) + NaNO₃(aq)
