Question

Give reason why an aqueous solution of ammonia acts as a weak base

Answer 1

Ammonia molecule contains a lone pair of electrons on N-atom, which accepts a proton from water, and forms ammonium ion and hydroxide ion, this makes ammonia solution alkaline and thus, it acts as a base.

NH₃ + H₂O → NH₄ ⁺ + OH^-

However, as the concentration of the hydroxyl ions that are furnished is less, therefore aqueous solution of ammonia acts as a weak base.