Question

Give the net ionic equation for the reaction (if any) that occurs when aqueous solutions of K2S and Fe(NO₃)₂ are mixed.

1) Fe₂⁺(aq) + S2-(aq) → FeS(s)
2) K⁺(aq) + NO₃⁻(aq) → KNO₃(s)
3) Fe₂⁺(aq) + S2-(aq) + 2K⁺(aq) + 2NO₃⁻(aq) → FeS(s) + 2K⁺(aq) + 2NO₃⁻(aq)
4) Fe₂⁺(aq) + S2-(aq) + 2K⁺(aq) + 2NO₃⁻(aq) → Fe₂⁺(aq) + S2-(aq) + 2K⁺(aq) + 2NO₃⁻(aq) + 2KNO₃(s)
5) No reaction occurs

Answer 1

The net ionic equation for the reaction when aqueous solutions of K2S and Fe(NO₃)₂ are mixed is 1) Fe²⁺(aq) + S²⁺(aq) → FeS(s), as iron(II) sulfide is an insoluble product and K⁺ and NO₃⁻ are spectator ions.

Step-by-step explanation:

When aqueous solutions of K2S (potassium sulfide) and Fe(NO₃)₂ (iron(II) nitrate) are mixed, we look for potential precipitates by considering the solubility rules. Sulfides (except when combined with alkali metals and calcium, strontium, or barium) typically form insoluble compounds, and the reaction between Fe²⁺ (from iron(II) nitrate) and S²⁺ (from potassium sulfide) will likely produce an insoluble compound, iron(II) sulfide (FeS). The potassium (K⁺) and nitrate (NO₃⁻) ions remain in solution and do not participate in a reaction, so they are considered as spectator ions. The net ionic equation for the reaction is:

Fe²⁺(aq) + S²⁺(aq) → FeS(s)