Question

The strength of an aqueous $\mathrm{NaOH}$ solution is most accurately determined by titrating: (Note: consider that an appropriate indicator is used)

• A. Aq. $\mathrm{NaOH}$ in a pipette and aqueous oxalic acid in a burette
• B. Aq. $\mathrm{NaOH}$ in a volumetric flask and concentrated ${\mathrm{H}}_2{\mathrm{SO}}_4$ in a conical flask
• C. Aq. $\mathrm{NaOH}$ in a burette and concentrated ${\mathrm{H}}_2{\mathrm{SO}}_4$ in a conical flask
• D. Aq. $\mathrm{NaOH}$ in a burette and aqueous oxalic acid in a conical flask

Answer 1

The correct option is D

Aq. $\mathrm{NaOH}$ in a burette and aqueous oxalic acid in a conical flask

Explanation for the correct option:

D: Aq. $\mathrm{NaOH}$ in a burette and aqueous oxalic acid in a conical flask

• 
• The strength of $\mathrm{NaOH}$ is determined by titrating it against oxalic acid in a burette with $\mathrm{NaOH}$ and oxalic acid in a conical flask.
• Because oxalic acid is a major standard and $\mathrm{NaOH}$ is a secondary standard, we constantly made fresh oxalic acid solutions.
• $2\mathrm{NaOH}+\mathrm{COOH}-\mathrm{COOH}⟶\mathrm{COONa}-\mathrm{NaCOO}+2{\mathrm{H}}_2\mathrm{O}$
• Typically, the standard solution is retained in the burette.
• ${\mathrm{H}}_2{\mathrm{SO}}_4$ is a secondary standard solution, whereas oxalic acid is a major standard solution.

Final Answer: Therefore, the correct answer is Option D.