Question

Which of the following is a strong base?

• A. Acetic acid
• B. Hydrochloric acid
• C. Sodium bicarbonate
• D. Sodium hydroxide

Answer 1

The correct option is D

Sodium hydroxide

Explanation for correct option:

D. Sodium hydroxide:

Bases

• Bases, according to Arrhenius's theory, are species that dissociate in water to produce hydroxyl ions ${\mathrm{OH}}^{-}$.
• According to Brönsted-Lowry theory, a base is a substance that can take a hydrogen ion, ${\mathrm{H}}^{+}$.
• According to Lewis's acid-base concept, the base is a species that donates an electron pair.
• Species such as ${\mathrm{H}}_2\mathrm{O}$, ${\mathrm{NH}}_3$ donates a pair of electrons. As a result, this species can serve as a Lewis base.

Sodium hydroxide$\left(\mathrm{NaOH}\right)$ is a strong base and when it is added to water, it produces Sodium $\left({\mathrm{Na}}^{+}\right)$ and Hydroxyl ions $\left({\mathrm{OH}}^{-}\right)$.

The chemical reaction can be depicted as:

$\mathrm{NaOH}\left(\mathrm{aq}\right)\to {\mathrm{Na}}^{+}\left(\mathrm{aq}\right)+{\mathrm{OH}}^{-}\left(\mathrm{aq}\right)$

Explanation for incorrect options:

A. Acetic acid $\left({\mathrm{CH}}_3\mathrm{COOH}\right)$ is a weak acid.

B. Hydrochloric acid $\left(\mathrm{HCl}\right)$ is a strong acid.

C. Sodium bicarbonate $\left({\mathrm{NaHCO}}_3\right)$ is a weak base.

Hence, the correct option is D i.e. Sodium hydroxide.