Distinguish by adding: Sodium hydroxide solution and ammonium hydroxide solution to
(c) Copper salt solution and ferrous salt solution.
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Solution
Sodium hydroxide on reaction with copper salt gives a pale blue precipitate Cu(OH)2 which is insoluble even in excess of NaOH, while with ferrous salt gives a dirty green precipitate Fe(OH)2 which is also insoluble in excess of NaOH.
FeSO4+2NaOH→Fe(OH)2+Na2SO4
CuSO4+2NaOH→Cu(OH)2↓+2NaSO4
Ammonium hydroxide on reaction with copper salt gives a pale blue precipitate Cu(OH)2 which is soluble in excess of NH4OH, while with ferrous salt gives a dirty green precipitate Fe(OH)2 which is insoluble in even excess of NH4OH.