Question

Why is $\mathrm{HCl}$ regarded as strong acid while ${\mathrm{CH}}_3\mathrm{COOH}$ is a weak acid?

Answer 1

Acid:

1. A molecule or chemical that can donate a proton or accept a pair of electrons is known as an acid.
2. A strong acid is one that is entirely ionized in an aqueous solution, whereas a weak acid is one that ionizes only slightly.
3. $\mathrm{HCl}$ is a strong acid because when dissolved, it dissociates almost completely, whereas ${\mathrm{CH}}_3\mathrm{COOH}$ is a weak acid because some ${\mathrm{H}}^{+}$ ions stay bonded within the molecule.
4. Reactions involved: $$\begin{gathered} \mathrm{HCl}\left(\mathrm{aq}\right)\to {\mathrm{H}}^{+}\left(\mathrm{aq}\right)+{\mathrm{Cl}}^{-}\left(\mathrm{aq}\right) \\ {\mathrm{CH}}_3\mathrm{COOH}\left(\mathrm{aq}\right)\rightleftharpoons {\mathrm{CH}}_3{\mathrm{COO}}^{-}\left(\mathrm{aq}\right)+{\mathrm{H}}^{+}\left(\mathrm{aq}\right) \end{gathered}$$

Hence, ${\mathrm{CH}}_3\mathrm{COOH}$is a weaker acid than $\mathrm{HCl}$.