Analytical ChemistryMedium
Question
An aqueous solution of a substance gives a white precipitate on treatment with dilute hydrochloric acid, which dissolves on heating on heating. When hydrogen sulphide is passed through the hot acidic, a black precipitate is obtained. The substance is a :
Options
A.Hg2+ salt
B.Cr+ salt
C.Ag+ salt
D.Pb+ salt
Solution
Pb2+ + 2HCl → PbCl2 ↓ + 2H+
white ppt.
PbCl2 is insoluble in cold water but soluble in hot water.
In hot solution. Pb2+ lons present react with H2S to form
Pb2+ + H2S → PbS ↓ + 2H+
Black
white ppt.
PbCl2 is insoluble in cold water but soluble in hot water.
In hot solution. Pb2+ lons present react with H2S to form
Pb2+ + H2S → PbS ↓ + 2H+
Black
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