Question

What happens when ammonia solution is added first dropwise and then in excess to FeCl3.

Answer 1

We know that ammonia solution is ammonium hydroxide.

When added in small quantity(dropwise), a reddish-brown precipitate of Fe(OH)3 is formed. This precipitate is insoluble in excess of ammonia solution.

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Answer 2

Answer:(i)CuSO4 + 2NH4OH ⟶ Cu(OH)2 ↓ (NH4)2 SO4 Blue pale blue ppt. colourless is solution With excess of NH4OH, ppt dissolves CU(OH)2 + (NH4)2SO4 + 2NH4OH ⟶ [Cu(NH3)4]SO4 + 4H2O Excess Tetrammine Copper(II) Sulphate (ii)ZnSO4 + 2NH4OH ⟶ Zn(OH)2 + (NH4)2 SO4 Colourless white, gelatinous ppt colourless With excess of NH4OH, ppt dissolves Zn(OH)2 + (NH4)2SO4 + 2NH4OH ⟶ [Zn(NH3)4]SO4 + 4H2O (excess) Tetramminezinc(II) Sulphate (colourless)

Explanation: