Question

Analysis of Cations

Describe how silver will be separated from the other cations. A complete answer will include the name of any reagents used to precipitate it and the formula of its precipitate.

Answer 1

Typically, silver will precipitate readily easy compared to another reactants

First, add HCl concentrated, and let the group 1 cations precipitate

Cations = Hg2+2; Ag+ and Pb+2

note that

Hg2Cl2 ; AgCl and PbCl2 form

Now,

Increase Temperature of solution, to T = 100°C

PbCl2 will become soluble

Hg2Cl2 and AgCl are present now in the solution as solid preciiptate

Add aqueous ammonia

NH3(aq)

AgCl(s) + 2NH3 --> Ag(NH3)2Cl(aq)

Hg2Cl2(s) + 2 NH3(aq) --> Hg(s) + HgNH2Cl(s) + NH4Cl(aq)

note that

Ag ion is now in solution, remove the precipitate via filtartion

so

Hg is removed

Now,

Ag is present as Ag(NH3)2Cl(aq)

add HNO3 to neutralize and lower pH

then

AgCl(s) will form

This way we separate the Ag+ ions from solution