Question

Dissociation of $ C{H_3}COOH $ is suppressed by adding
A. $ HCl $
B. $ {H_2}S{O_4} $
C. $ C{H_3}COONa $
D. Any of the above

Answer 1

Hint: Acetic acid, commonly referred to as ethanoic acid, is a weak acid with the formula $ C{H_3}COOH $ . When dissolved in water, acetic acid dissociates only partially into its constituent ions, making it a weak acid.

Complete answer:
The addition of acetate ions from sodium acetate suppresses acetic acid ionisation and shifts its equilibrium to the left, according to Le Chatelier's principle. As a result, the acetic acid's percent dissociation decreases and the pH of the solution increases.
The common ion effect occurs when a common ion is added to two solutes, causing precipitation or reducing ionisation. You're familiar with Le Chatelier's principle, which states that until exerted on by an outside force, a reaction will remain in equilibrium until the force is removed, at which point the reaction will shift to accommodate the force and re-establish equilibrium.
Hence, the correct option is C. $ C{H_3}COONa $ .

Additional Information:
In transition metal complexes, Common ion effect is not observed. This is due to the d-block element's tendency for forming complex ions. Cuprous chloride, which is insoluble in water, is a good example of this. The common ion effect is employed in water treatment to precipitate calcium carbonate (which is sparingly soluble) from the water by adding sodium carbonate (which is highly soluble).

Note:
When weak acids are dissolved in water, they do not entirely break down into their constituent ions. When the weak acid is dissolved in water, an equilibrium between the concentration of the weak acid and its constituent ions is established.