Question

In conductometric titration of acetic acid with 0.1 N sodium hydroxide, complete neutralization occurs. Further addition of titrant results in

• A. Increase the conductance
• B. Decrease the conductance
• C. No change in the conductance
• D. Colour change (orange to red)

Hint:

In weak acid–strong base conductometric titrations, conductance increases sharply after the equivalence point due to the presence of excess hydroxide ions.

Answer 1

The Correct Option is A

Conductometric titration involves the measurement of electrical conductance during a chemical reaction. When titrating a weak acid like acetic acid (CH\textsubscript{3}COOH) with a strong base like sodium hydroxide (NaOH), the neutralization reaction is: \[ \text{CH}_3\text{COOH} + \text{NaOH} \rightarrow \text{CH}_3\text{COONa} + \text{H}_2\text{O} \] Initially, conductance is low due to partial ionization of acetic acid. As NaOH is added, H\textsuperscript{+} ions are replaced by highly mobile Na\textsuperscript{+} ions, slightly increasing conductance. At the equivalence point, the solution contains sodium acetate, which is a salt of a weak acid and contributes moderately to conductance. Beyond the equivalence point, excess NaOH adds OH\textsuperscript{−} ions, which are very mobile and significantly increase the conductance. Thus, further addition of titrant (NaOH) after neutralization leads to a noticeable increase in conductance.