Question

Aqueous solution of acetic acid contains:
(This question has multiple correct options)
A. $C{H_3}CO{O^ - }$
B. ${H_3}{O^ + }$
C. $C{H_3}COOH$
D. ${H^ + }$

Answer 1

Hint: We know that a weak acid is the one which does not dissociate completely in its aqueous solution and these weak acids dissociate or ionize in aqueous solution to a very moderate extent and mainly consist of unionized form of the acid, only a small amount of hydronium ions and the conjugate base of the weak acid.

Complete answer:
Acetic acid which is also known as ethanoic acid has a chemical formula $C{H_3}COOH$. It is a colourless liquid and organic compound. Because of the presence of protons, it shows acidic character. Acetic acid is a weak monoprotic acid and in aqueous solution, it has the $p{K_a}$ value of $4.76$. In very dilute solution, more than $90\% $ of the acetic acid gets dissociated and the reaction takes place as follows:
$C{H_3}COOH + {H_2}O \rightleftharpoons C{H_3}CO{O^ - } + {H_3}{O^ + }$
Thus, the aqueous solution of acetic acid consist of:
1. The conjugate base i.e., acetate ion $C{H_3}CO{O^ - }$
2. Hydronium ion i.e., ${H_3}{O^ + }$
3. Unionized acetic acid i.e., $C{H_3}COOH$
Hence, option (A), (B) and (C) are the right answers.

Additional information-
In the solutions having concentration greater than${10^{ - 6}}M$, the dissociation of acetic acid takes place merely up to $0.4\% $. Acetic acid is an important chemical reagent mainly used in the production of vinyl acetate monomer followed by the acetic anhydride and ester production and is the main component of vinegar apart from water as vinegar consists of $4\% $ acetic acid by volume.

Note:
It is important to note that in case of strong acids, complete dissociation takes place in the aqueous solution by losing the protons. In case of a strong acid, the concentration of hydronium ions formed will be equal to the concentration of strong acid introduced to the solution whereas in case of weak acid, the concentration of hydronium ions formed is always less than the concentration of acid introduced to the solution.