Reaction of lead acetate with hydrogen sulfide
In a clean vessel, fill the lead acetate solution. The liquid is clear and colorless, and let it stand.

In another vessel, take hydrogen sulfide gas and slowly introduce it into the lead acetate solution. When the side is introduced, bubbles can be seen rising in the liquid. Russia, the solution gradually changes, and it is slightly hazy at first, and then a black precipitate is slowly formed. This black precipitate is also lead sulfide.

Investigate the reason for its reaction, and cover lead acetate $[Pb (CH_ {3} COO) _ {2}] $interacts with hydrogen sulfide $ (H_ {2} S) $. The sulfur ion $ (S ^ {2 -}) $in hydrogen sulfide combines with the lead ion $ (Pb ^ {2 +}) $in lead acetate, resulting in the precipitation of lead sulfide $ (PbS) $. The chemical reaction equation is: $Pb (CH_ {3} COO) _ {2} + H_ {2} S = PbS\ downarrow + 2CH_ {3} COOH $. Looking at this reaction, it can be seen that when different substances meet, they often change due to different chemical properties, or there is precipitation, or gas, or discoloration, etc., all of which are of chemical interest.