Question

The pH of an aqueous solution of sodium acetate is

• A. more than 7.
• B. less than 7.
• C. equal to 7.
• D. more than 10.

Answer 1

The correct option is A

more than 7.

The explanation for the correct option (A):

• A salt is a compound formed from an acid by the replacement of the Hydrogen ($\mathrm{H}$) in the acid by a metal.
• Example: Hydrochloric acid ($\mathrm{HCl}$) is an acid. When the $\mathrm{H}$ of $\mathrm{HCl}$ is replaced by a metal atom, say a Sodium atom ($\mathrm{Na}$), then it results in the formation of a salt Sodium chloride ($\mathrm{NaCl}$).
• Sodium acetate (${\mathrm{CH}}_3\mathrm{COONa}$) is a salt. The aqueous solutions of many salts are neutral (pH = 7) but some salts form acidic or basic solutions when dissolved in Water (${\mathrm{H}}_2\mathrm{O}$).
• The acidic and basic nature of some salt solutions can be determined by the hydrolysis of salts.
• The salts of strong acids and strong bases produce solutions which are neutral in nature.
• The salts of strong acids and weak bases produce solutions which are acidic in nature.
• The salts of weak acids and strong bases produce solutions which are basic in nature.
• The hydrolysis of ${\mathrm{CH}}_3\mathrm{COONa}$ produces Acetic acid (${\mathrm{CH}}_3\mathrm{COOH}$) and Sodium hydroxide ($\mathrm{NaOH}$). The equation is:

${\mathrm{CH}}_3\mathrm{COONa}+{\mathrm{H}}_2\mathrm{O}\to {\mathrm{CH}}_3\mathrm{COOH}+\mathrm{NaOH}$

• In this reaction $\mathrm{NaOH}$ is a strong base and ${\mathrm{CH}}_3\mathrm{COOH}$ is a weak acid and therefore, the aqueous solution of ${\mathrm{CH}}_3\mathrm{COONa}$ is basic in nature. For the basic solution, the value of pH is more than 7.

Final Answer: Hence, option (A) is correct. The pH of an aqueous solution of sodium acetate is more than 7.