Question

analyzing a mixture salts with differing cations and/or anions can be far more complicated than analyzing a single simple salts. Interference between cations or between an anions can greatly increase the complexity of the result. Using sound chemical knowledge, suppose your simple salts is white granular solid. At what specific step in the cations procedure might you begin your analysis ? explain your reasoning

Answer 1

The silver group of ions — silver(I) (Ag+), lead(II) (Pb2+), and mercury(I) (Hg2 2+) — is a chemically related subgroup of ions.

They are the only common metal cations that form insoluble precipitates with chloride ion.

For example, Ag+(aq) + Cl- (aq) → AgCl(s)

The first step in separating the three chlorides is to treat the solid mixture with hot water to selectively dissolve PbCl2 and to leave AgCl and Hg2Cl2 as a solid mixture.

When relatively concentrated ammonia is added to the mixture of solids AgCl and Hg2Cl2, the silver chloride precipitate is dissolved. However, Hg2Cl2 also reacts with NH3, but in a different manner. Mercury(I) chloride can undergo what is known as a disproportionation reaction. That is, the mercury(I) ion is both oxidized [to mercury(II), Hg2+] and reduced (to metallic mercury). Hg2Cl2(s) → Hg(liq) + Hg2+(aq) + 2 Cl–(aq)