Analytical ChemistryHard
Question
NH4SCN can be used to test one or more out of Fe3+, Co2+,Cu2+ :
Options
A.Fe3+ only
B.Co2+ , Cu2+ only
C.Fe3+ Cu2+ only
D.All
Solution
Fe3+ + 3SCN- → Fe(SCN)3 (deep red colouration)
Co2+ + 4SCN-
[Co(SCN)4]2- (blue colouration)
Cu2+ + 2SCN- → Cu(SCN)2 ↓(black) ; 2Cu(SCN)2 → 2CuSCN ↓(white) + (SCN)2.
Co2+ + 4SCN-
[Co(SCN)4]2- (blue colouration)Cu2+ + 2SCN- → Cu(SCN)2 ↓(black) ; 2Cu(SCN)2 → 2CuSCN ↓(white) + (SCN)2.
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