Question

Which compound does not form a precipitate when reacted with sodium hydroxide?

Answer 1

Answer:

NaNO₃

Explanation:

A precipitate is a compound or a salt formed from a precipitation reaction and does not dissolve in water and therefore will exist in solid state.

From the choices given precipitation reaction will occur between;

• Fe(NO₃)₃(aq) + 3NaOH(aq) → Fe(OH)₃(s) + 3NaNO₃(aq)
• Cu(NO₃)₂(aq) + 2NaOH(aq) → Cu(OH)₂(s) + 2NaNO₃(aq)
• FeSO₄(aq) + 2NaOH(aq) → Fe(OH)₂(s) + Na₂SO₄(aq)

Fe(OH)₃, Cu(OH)₂, and Fe(OH)₂ are precipitates.

From the rules of solubility, hydroxides are insoluble except Ca(OH)₂ which is slightly soluble and hydroxides of ammonium and alkali metals.