Question

What is the formula of liquid ammonia? Account for the basic nature of this compound.

Answer 1

Hint: Ammonia molecule is made up of nitrogen and hydrogen atoms. It is a colorless and pungent-smelling gas but it easily liquefies due to the formation of hydrogen bonds between molecules. The basic nature of the compound is attributed to its electron-donating nature.

Complete answer:
Ammonia is a hydride of nitrogen that exists as a colorless and pungent-smelling gas. Due to the electronegativity difference between the nitrogen and hydrogen atoms, hydrogen bonding is possible between the molecules of ammonia. And that is why it is found in liquid form also.
So, the formula of liquid ammonia is $\text{N}{{\text{H}}_{3}}$. Here, the nitrogen is $\text{s}{{\text{p}}^{3}}$ hybridized and possesses a lone pair of electrons on the nitrogen atom. According to Lewis's theory of acids and bases, any electron-donating species act as a base. So, the liquid ammonia also acts as a base.
It readily dissolves in water and forms ammonium hydroxide that further furnishes hydroxyl ions which makes the medium basic. The reaction involved can be written as follows:
\[\begin{align}
  & \text{N}{{\text{H}}_{\text{3}}}+{{\text{H}}_{\text{2}}}\text{O}\to \text{N}{{\text{H}}_{\text{4}}}\text{OH} \\
 & \text{N}{{\text{H}}_{\text{4}}}\text{OH}\rightleftharpoons \text{NH}_{\text{4}}^{\text{+}}+\text{O}{{\text{H}}^{\text{-}}} \\
\end{align}\]
Thus, liquid ammonia has the molecular formula of $\text{N}{{\text{H}}_{\text{3}}}$ and it is basic in nature.

Additional information:
Liquid ammonia is also used as a non-aqueous solvent. It dissolves some alkali and alkaline earth metals and produces a blue-colored solution due to the presence of solvated electrons.

Note:
Liquid ammonia is used as a solvent for some organic compounds due to its low dielectric constant value than that of water. But this value is somewhat high enough for ammonia to act as a good ionizing solvent.