Question

Ammonia is the weak base that reacts with water according to the equation:

$N{H}_3\left(aq\right)+H_{2}O\left(l\right)\rightleftharpoons N{H}_4^{+}\left(aq\right)+O{H}^{-}\left(aq\right)$

Will any of the following increase the per cent of ammonia that is converted to the ammonium ion in water?

• A. Addition of $NaOH$
• B. Addition of $HCl$
• C. Addition of $N{H}_{4}Cl$
• D. None of these

Answer 1

Answer: (B)

Addition of $HCl$

$N{H}_3\left(aq\right)+H_{2}O\left(l\right)\rightleftharpoons N{H}_4^{+}\left(aq\right)+O{H}^{(}aq)$

When HCl is added, the hydrogen ions will neutralize hydroxide ions to form water. The equilibrium will shift in the forward direction so that more hydroxide ions are obtained. This will increase the percentage of ammonia that is converted to ammonium ions in water.

Hence, option B is correct.