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 a?
A
Cu(OH)2
B
CuSo4.5H2O
C
(NH4)2SO4
D
Cu(NH3)4(OH)2
E
CuSO4.(NH4)2SO4.2H2O
Verified Correct Answer: D.
Chemical Principles & Mechanism
\(CuSO_4+2NH_4OH→(NH_4)_2SO_4+Cu(OH)_2\)(pale−blue)
The pale blue precipitate of copper hydroxide dissolves in excess of ammonium hydroxide forming tetraamine copper [II] sulphate, an azure blue(deep blue) soluble complex salt.
\(Cu(OH)_2+(NH_4)_2SO_4+2NH_4OH→[Cu(NH_3)_4]SO_4+4H_2O\)
Source: WAEC / JAMB / NECO Classroom Archive (Record #44491)