Question

Which of the following is the correct order in terms of increasing acidic strength?

• A. Water $<$ Acetic acid $<$ Hydrochloric acid
• B. Water $<$ Hydrochloric acid $<$ Acetic acid
• C. Acetic acid $<$ Water $<$ Hydrochloric acid
• D. Hydrochloric acid $<$ Water $<$ Acetic acid

Answer 1

The correct option is A Water $<$ Acetic acid $<$ Hydrochloric acid

The strength of an acid depends on its ability or tendency to lose a proton from it. A strong acid is one that completely dissociates or ionizes in a solution. In water, one mole of a strong acid dissolves completely to yield cation and anion.

Strong acids are hydrochloric acid, nitric acid, sulphuric acid, etc. In an aqueous solution, they ionize completely. Weak acids only partially dissociate. Examples are carbonic acid or acetic acid.

The stronger an acid, the more easily it loses a proton. Acetic acid is a weak acid, while $HCl$ ionizes completely. The weakest acidic strength of them all is that of water.

The dissociation of an acid (say $HA$) is given below:

$HA\left(aq\right)\to H^{+}\left(aq\right)+A^{-}\left(aq\right)$