A solution containing a mixture of metal cations was treated as follows. 1. Dilu

Question

A solution containing a mixture of metal cations was treated as follows.
1. Dilute HCl was added and a precipitate formed. The precipitate was filtered off.
2. H2S was bubbled through the acidic solution. Again, a precipitate formed and was filtered off.  
3. The pH was raised to about 9 and H2S was again bubbled through the solution. No precipitate formed.  
4. Finally, sodium carbonate was added, a precipiate formed and was filtered off
What can be said about the presence of each of these groups of cations in the original solution?
a) Ag+; Pb2+; Hg2^2+ description: form insoluble chlorides
b) Bi3+; Cd2+; Cu2+; Hg2+; Pb2+; Sb3+; Sn2+; Sn4+ description: form acid-insoluble sulfides
c) Al3+; Co2+; Cr3+; Fe2+; Fe3+; Ni2+; Mn2+; Zn2+ description: form base-insoluble sulfides or hydroxides
d) Ba2+; Ca2+; Mg2+; Sr2+ description: form insoluble carbonates
e) Li+; Na+; K+; NH4+ description: completely soluble

The answer choices for matching to each group are: *choices can be used more than once*
All of these ions are present
None of these ions are present
Unknown
At least one of these ions were present

Explanation / Answer

Options (a), (b), (d) are correct. Cations of Group I, Group II, and Group IV are present in a mixture of metal cations. There is no specific test performed for Group V metal cations like Li+, Na+, K+, NH4+,so it is doubtful these are present or not in a mixture.

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