passwella.
Menu

JAMB Chemistry 1980 Question 33

Question 33

Qualitative Analysis

When copper (II) sulphate solution is treated with excess ammonium hydroxide, a precipitate is first formed, and then this dissolves to give a deep blue solution. This deep blue solution is

  1. A.Cu(OH)2
  2. B.CuSO4.5H2O
  3. C.(NH4)2SO4
  4. D.Cu(NH3)4(OH)2
  5. E.CuSO4.(NH4)2SO4.2H2O.
Show the answer and explanation

Answer: D (Cu(NH3)4(OH)2)

Explanation

The pale blue Cu(OH)2 precipitate dissolves in excess ammonia to form the deep blue tetraamminecopper(II) complex.