Fig. 15.2 summarizes the classic method for separating a mixture of common cations by selective precipitation. Explain the chemistry involved with each of the four steps in the diagram.

Fig. 15.2

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Precipitate Ag", Pb²*, Hg: Cu²*, Bi³¹, Cd²*, Pb²+, Hg, As". Sb³*, Sn. AP, Fe, Fe, Co, Ni, Cr³, Zn, Mn Ba, Ca, Mg Na, K, NH, Group 1-Insoluble chlorides: AgCl, HgCl₂, PbCl₂ Precipitate Group II-Acid-insoluble sulfides: CuS, Bi S3, CdS, PbS, H₂S, As2S₁, Sb₂S3, SS₂ Precipitate Add HCl(aq) Precipitate Group III-Base-insoluble sulfides and hydroxides: Al(OH), Fe(OH)3, Cr(OH), ZS, NIS, COS, MuS, Fes Group IV-Insoluble carbonates: BaCO,, CaCO,, MgCO, Solution of Groups II-V Add H₂S Solution of Groups III-V Add NaOH Solution of Groups IV-V Add NaCO3(aq) Group V- Alkali metal ions and NH₂