Question

Is ammonia a base or acid?

Answer 1

Acid or base:

1. Any molecule that accepts a proton is a base, whereas any molecule that releases a proton is an acid.
2. As a member of group $5$, nitrogen has five valence electrons in ${\mathrm{NH}}_3$. The three hydrogen atoms are each adding one electron to complete their octet, or eight electrons or four pairs.
3. One of the pairs is a lone pair since the nitrogen is only forming three bonds.
4. In general, we know that a nitrogen atom with three bonds and one pair of unpaired electrons functions as a proton acceptor (base).
5. Also ammonia does not have any hydroxide ions, when it is dissolved in water, it collects hydrogen ions from the water and produces both hydroxide and ammonium ions
6. .$\underset{\mathrm{Ammonia}}{{\mathrm{NH}}_3\left(\mathrm{aq}\right)}+\underset{\mathrm{water}}{{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)}\to \underset{\mathrm{Ammonium}\mathrm{ion}}{{{\mathrm{NH}}_4}^{+}\left(\mathrm{aq}\right)}+\underset{\mathrm{Hydroxide}\mathrm{ion}}{{\mathrm{OH}}^{-}\left(\mathrm{aq}\right)}$
7. Ammonia is a weak base since it does not completely ionize to hydroxide and ammonium ions. When it ionizes, some of the ammonia molecules are still bonded together.

Therefore, ammonia is a weak base.