sapling earning olution containing a mixture of metal cations was treated with d

Question

sapling earning olution containing a mixture of metal cations was treated with dilute HCI and a precipitate formed. The solution was filtered and H2S was bubbled through the acidic solution. A precipitate again formed and was filtered off. Then, the pH was raised to about 8 and H2S was again bubbled through the solution. This time, no precipitate formed. Finally, the solution was treated with a sodium carbonate solution, which resulted in formation of a precipitate. Which metal ions were definitely present, which were definitely absent, and which may or may not have been present in the original mixture? Definitely present Definitely absent Possibly present

Explanation / Answer

For qualitative salt analysis metal cations are grouped into several groups with respect to their reactivity with certain reagents.

Group 1(Ag+,pb2+,Hg2+)-insoluble chlorides so gets precipitated with dil HCl.

Group 2(Cu2+,Sb3+,) very insoluble sulfides ,so ppt with H2S.

Group 3 (Ni2+,Mn2+,Co2+) gets ppt with basic H2S

Group 4 (Mg2+,Ba2+) insoluble carbonates ,gets ppt with NaCO3

Grp 5(K+) no ppt with HCl or H2S

So

Definitely present-Pb2+.Ba2+,Mn2+,Ni2+,Co2+,Mg2+,Ag+,Sb3+,Cu2+,Hg2+

definitely absent-Sn2+,Hg2 2+

possibly present-K+

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