Question

Insoluble sulfide compounds are generally black in color.

Answer 1

Answer:

Li₂S(aq)+Pb(NO₃)₂(aq) → PbS(s) + LiNO₃(aq)

K2S(aq)+Sn(NO₃)₄(aq→ SnS(s) + KNO₃(aq)

Explanation:

• According to solubility rules, metal sulfides are insoluble except Calcium sulfide(CaS), Magnesium sulfide(MgS), Barium sulfide(BaS), and those of potassium, sodium, and ammonium.
• Therefore, when all the other sulfides are formed during a reaction they form a precipitate that is shown to be in solid-state.
• Precipitates are formed during precipitation reactions when cations and anions combine to form a compound that is insoluble in water.

In our case; In the equations given, some reactions will take place to form a precipitate while others will not occur.

That is;

• Na₂S(aq)+KCl(aq) → No reaction
• Li₂S(aq)+Pb(NO₃)₂(aq) → PbS(s) + LiNO₃(aq)
• Pb(ClO₃)₂(aq)+NaNO₃(aq) → No reaction
• AgNO₃(aq)+KCl(aq) →AgCl(s) + KNO₃(aq)
• K2S(aq)+Sn(NO₃)₄(aq→ SnS(s) + KNO₃(aq)

The first reaction will not occur.

The second equation is a precipitation reaction that forms lead(ii)sulfide which is a black precipitate.

The third reaction will not take place.

The fourth reaction will be a precipitation reaction forming silver chloride precipitate.

The fifth equation is also a precipitation reaction that forms tin(ii) sulfide, SnS which is a black precipitate.

Therefore; the equations that answers our question are;

• Li₂S(aq)+Pb(NO₃)₂(aq) → PbS(s) + LiNO₃(aq)
• K2S(aq)+Sn(NO₃)₄(aq→ SnS(s) + KNO₃(aq)