Question

Propose a test based on the qualitative analysis scheme which would allow you to distinguish between

1) Pb^ 2+ (aq) and Ag+ (aq)

2) PbCl2 (s) and PbCrO4 (s)

Answer 1

1) If we add dil HCl to the solution containing Pb^2+ (aq) then white precipitate is formed, on heating this precipitate dissolved in hot water.

If we add dil HCl to the solution containing Ag^+ (aq) then white precipitate is formed in this case also, but on heating this precipitate is not dissolved in hot water.

In this way we can distinguish these two ions.

2) PbCl2(s) is white solid where PbCrO4 is yellow solid.

By observing color we can distinguish these two solids.