Question

How does ammonia react with the solution of cu 2 +?

Answer 1

Ammonia acts as a Lewis base due to the presence of lone pair of electrons on the nitrogen atom.Therefore,it can form coordinate bond with electron deficient molecules or a number of transition metal cations to from complex compounds.Ammonia reacts with a solution of Cu2+ to from a deep blue coloured complex.The reaction for the above complex can be written as follows:

Cu2+(aq) + 4 NH3(aq)   ⇔  [Cu(NH3)4]2+(aq)

Blue                                         Deep Blue

This property of ammonia to form complex compounds is useful in detection of metal ions.

Answer 2

Answer :

Ammonia on reacting with Cu2+ acts as a Lewis base and donates its electron pair to the metal ion and forms a linkage with the metal ion.

Cu2+ (aq) +4NH3 (aq)  ------> [Cu(NH3)4]2+ (aq)

Here, colour of Cu2+ is blue whereas the colour of [Cu(NH3)4]2+ is deep blue.