Question

Which of the following statements is true concerning an aqueous solution of the weak base NH3?

A. OH– is a stronger base than NH3.
B. NH3 is a weaker base than H2O.
C. OH– is a stronger acid than NH4+.
D. H2O is a stronger acid than H3O+.
E. NH4+ is a stronger acid than H3O+.

Answer 1

Answer: Option (A) is the correct answer.

Explanation:

When weak base $NH_{3}$ is dissolved in water then the reaction will be as follows.

       $NH_{3} + H_{2}O \rightarrow NH^{+}_{4} + OH^{-}$

When $NH_{3}$ is compared with water then oxygen atom of $H_{2}O$ being more electronegative in nature will keep its lone pair of electrons towards itself.

Hence, water will act as a neutral molecule and hence, $NH_{3}$ will act as a stronger base as compared to $H_{2}O$.

On the other hand, $OH^{-}$ will have both lone pair of electrons and a negative charge. Hence, its electron density is much more as compared to $NH_{3}$ that only contains a lone pair of electron.

Therefore, $NH_{3}$ will act as a weak base as compared to $OH^{-}$.

Thus, we can conclude that the statement $OH^{-}$ is a stronger base than $NH_{3}$, is true concerning an aqueous solution of the weak base $NH_{3}$.