State your observations when ammonium hydroxide solution is added drop by drop and then in excess to each of the following solutions:

(i) copper sulphate solution

(ii) zinc sulphate solution.

Question

State your observations when ammonium hydroxide solution is added drop by drop and then in excess to each of the following solutions: (i) copper sulphate solution (ii) zinc sulphate solution.

Accepted Answer

(i) Pale blue precipitate of Cu(OH) 2 is formed, which becomes deep blue when excess of ammonium hydroxide is added. CuSO 4 + 2NH 4 OH ⟶ (NH 4 ) 2 SO 4 + Cu(OH) 2 ↓ Cu(OH) 2 + (NH 4 ) 2 SO 4 + 2NH 4 OH [in excess] ⟶ 4H 2 O + [Cu(NH 3 ) 4 ]SO 4 (ii) Gelatinous white precipitate of zinc hydroxide is formed which becomes colourless solution on adding excess of ammonium hydroxide. ZnSO 4 + 2NH 4 OH ⟶ (NH 4 ) 2 SO 4 + Zn(OH) 2 ↓ Zn(OH) 2 +(NH 4 ) 2 SO 4 + 2NH 4 OH [in excess] ⟶ 4H 2 O + [Zn(NH 3 ) 4 ]SO 4

State your observations when ammonium hydroxide solution is added drop by drop and then in excess to each of the following solutions:

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