Question

Identify the cation: Ammonium hydroxide solution when added to the solution gives bluish white precipitate which dissolves in excess to give deep blue solution.

Answer 1

Answer:

(i) A bluish white precipitate appears which dissolves in excess of NH

4

OH and give an inky blue solution of tetra-amino copper sulphate.

(ii) A gelatinous white precipitate appears which dissolves in excess of NH

4

OH and give a clear transparent colourless solution of tetraamine zinc sulphate.

Answer 2

When NH4OH solution is added drop by drop to copper sulphate solution a pale blue / bluish white precipitate is formed which is soluble in excess of NH4OH and deep blue / inky blue solution is formed. 

CuSO4+2NH4OH→Cu(OH)2+(NH4)2SO4 

Cu(OH)2+4NH4OH→Cu(NH3)4(OH)2+4H2O