Question

Write the complete ionic equation for the reaction, if any, when aqueous solutions of sodium sulfide and iron(III) nitrate are mixed.

a) Na⁺ + S²⁻ + Fe³⁺ + 3NO₃⁻ → Na⁺ + NO₃⁻ + FeS(s)
b) 2Na⁺ + S²⁻ + 2Fe³⁺ + 6NO₃⁻ → 2Na⁺ + 6NO₃⁻ + 2FeS(s)
c) 3Na⁺ + 2S²⁻ + Fe³⁺ + 3NO₃⁻ → 3Na⁺ + 3NO₃⁻ + Fe₂S₃(s)
d) Na⁺ + S²⁻ + Fe³⁺ + 2NO₃⁻ → Na⁺ + 2NO₃⁻ + Fe₂S₃(s)

Answer 1

The correct complete ionic equation for the reaction of aqueous sodium sulfide and iron(III) nitrate is 2Na+ (aq) + S2− (aq) + 2Fe3+ (aq) + 6NO3− (aq) → 2Na+ (aq) + 6NO3− (aq) + 2FeS(s), which corresponds to option b.

Step-by-step explanation:

The correct complete ionic equation for the reaction when aqueous solutions of sodium sulfide and iron(III) nitrate are mixed is:

2Na

+

(aq) + S

2−

(aq) + 2Fe

3+

(aq) + 6NO

3

−

(aq) → 2Na

+

(aq) + 6NO

3

−

(aq) + 2FeS(s)

This is represented by option b). When mixed, iron(III) nitrate and sodium sulfide react to form solid iron(II) sulfide and sodium nitrate, which remains in the aqueous state.

Sodium ions (Na+) and nitrate ions (NO3−) are spectator ions, meaning they do not participate in the reaction, and so they appear on both sides of the equation unchanged. When sodium sulfide (Na2S) and iron(III) nitrate (Fe(NO3)3) are combined, a precipitate of iron(II) sulfide (FeS) is formed, and this is the driving force of the reaction.