Question

Assertion :Assertion : The pH of an aqueous solution of acetic acid remains unchanged on addition of sodium acetate. Reason: Reason : The ionization of acetic acid is increased by addition of sodium acetate.

• A. If both the assertion and reason are true and reason is the correct explanation of assertion.
• B. If both the assertion and reason are true but reason is not the correct explanation of assertion.
• C. If assertion is true but reason is false
• D. If both assertion and reason are false.

Answer 1

The correct option is D If both assertion and reason are false.

Addition of a small amount of $C{H}_{3}COONa$ to acetic acid increases the pH value because $C{H}_{3}COONa$ is a strong electrolyte and thus ionizes to give $C{H}_{3}CO{O}^{-}$ and $N{a}^{+}$ ions. Due to common ion effect, it suppresses the ionization of $C{H}_{3}COOH$ which decreases $\left[H^{+}\right]$ and hence pH value increases.