Analytical ChemistryHard
Question
Which of the following statements is/are true ?
Options
A.Ag+ ions do not give white precipitate with concentrated HCl.
B.Cu2+ ions produce a white precipitate when KCN solution is added in a small quantity.
C.Hg2+ ions give deep blue precipitate with cobalt acetate and ammonium thiocyanate.
D.Black precipitate of BiI3 turns orange when heated with water.
Solution
(A) Ag+ + Cl- → AgCl ↑ ; AgCl + Cl- → [AgCl2]- (soluble complex).
(B) Cu2+ + 2CN- → Cu(CN)2 ↓ (yellow). ; Cu(CN)2 ↓ → 2 CuCN ↓(white) + (CN)2.
(C) (CH3COO)2Co + 2NH4SCN → Co(SCN)2 + 2CH3COONH4.
Hg2+ + Co2+ + 4SCN- → Co[Hg(SCN)4] ↓ (deep-blue).
(D) BiI3 ↓ + H2O → BiOI ↓ (orange) + 2H+ + 2I-.
(B) Cu2+ + 2CN- → Cu(CN)2 ↓ (yellow). ; Cu(CN)2 ↓ → 2 CuCN ↓(white) + (CN)2.
(C) (CH3COO)2Co + 2NH4SCN → Co(SCN)2 + 2CH3COONH4.
Hg2+ + Co2+ + 4SCN- → Co[Hg(SCN)4] ↓ (deep-blue).
(D) BiI3 ↓ + H2O → BiOI ↓ (orange) + 2H+ + 2I-.
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