[Kstre]

Hi, I am helping my sister to make a chart for qualitative analysis. As it passed a while since I have learned it, I need someone to check what we did. It's about cations (attached). Is it correct?

[Kstre]

We are running out of time. Could someone please look at this (I and V groups are not important)?

[Borek]

It is slightly different from the scheme I know and can check in the books I have here. Hg²⁺ and Cu²⁺ are in the group IIA while Sn²⁺ is in IIB. Group III is not split into two subgroups.

[Kstre]

Thanks for the reply.
-I added the ones from II_a and II_b in the same group because I think that they can be deposited with the same reagents (I am not sure, so I asked for help).
-The opposite is for the III group, I separated those cations based on the reagent they could be deposited with.
-I suppose that the IV group can be excluded from further discussion, because it is an easy one. I need only II and III now, if you can say if there could be possible masking of a cation from one group by a cation from another group or judge everything as good. The differences inside the groups don't matter at the moment.

[Borek]

I added the ones from II_a and II_b in the same group because I think that they can be deposited with the same reagents

Yes, they are precipitated together. IIB can be then dissolved in KOH in the presence of H₂O₂.

The opposite is for the III group, I separated those cations based on the reagent they could be deposited with.

Procedure from my book calls for addition of solid NH₄Cl, then ammonia till the solution gets basic (against universal pH strip) , then thioacetamide and on heating all cations from the group III should precipitate together.

[Kstre]

Thanks again for helping. So there exhibits a method to distinguish Sn²⁺ from the others immediately, then the II group is clear, too. Only III left.
If just NH₄and then ammonia are added, the III_b won't precipitate, while the III_a will, right?

[Borek]

If just NH₄and then ammonia are added, the III_b won't precipitate, while the III_a will, right?

As I wrote - the book I have here doesn't discuss this approach, and I don't feel confident enough to predict details, too many factors.

[Kstre]

I guess then, as I thought from the beginning, that there is no other way than to find a lab and try it. Anyway thanks for your effort, we appreciate it.