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PPT Slide
Qualitative Analysis for Metallic Elements
- We can separate a complicated mixture of ions into five groups:
- Add 6 M HCl to precipitate insoluble chlorides (AgCl, Hg2Cl2, and PbCl2).
- To the remaining mix of cations, add H2S in 0.2 M HCl to remove acid insoluble sulfides (e.g. CuS, Bi2S3, CdS, PbS, HgS, etc.).
- To the remaining mix, add (NH4)2S at pH 8 to remove base insoluble sulfides and hydroxides (e.g. Al(OH)3, Fe(OH)3, ZnS, NiS, CoS, etc.).
- To the remaining mixture add (NH4)2HPO4 to remove insoluble phosphates (Ba3(PO4)2, Ca3(PO4)2, MgNH4PO4).
- The final mixture contains alkali metal ions and NH4+.
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