Question

why solution of ammonia is weak alkali

Answer 1

Ammonia is a typical weak base. Ammonia itself obviously doesn't contain hydroxide ions, but it reacts with water to produce ammonium ions and hydroxide ions.

However, the reaction is reversible, and at any one time about 99% of the ammonia is still present as ammonia molecules.

Answer 2

The aqueous solution of ammonia is weak alkali because ammonia produces OH- ions in it's water solution.

- Initially ammonia doesn't have any kind of OH- or hydroxyl ions.

- But when ammonia reacts with the water ,some amount of water is dissociated and forms OH- ions with the help of the mixed ammonia.

Chemical equation :

NH3 + H2O ---> (NH4+) + (OH-)

- Due to the presence of OH- or hydroxyl ions in the solution,the aqueous solution of ammonia is considered as a weak alkali.