Question

Choose the correct statement in a potentiometric titration: Salt bridge is used as

• A. Prevent contamination of reference electrode to test solution
• B. Only I
• C. I and III
• D. I and IV

Hint:

Salt bridges ensure ionic continuity and prevent liquid junction potential while protecting the test solution from contamination.

Answer 1

The Correct Option is C

- In potentiometric titration, the salt bridge plays a crucial role in maintaining the electrical neutrality between the reference and the indicator electrodes without allowing mixing of their respective solutions.
- Statement (i) is correct: The salt bridge prevents contamination between the reference electrode (such as calomel or silver-silver chloride) and the test (analyte) solution by providing an ionic connection.
- Statement (iv) is also correct: Salt bridges are often prepared using electrolytes such as KCl or KNO$_3$ , and are solidified with 3% agar or gelatin to prevent flow and mixing of liquids while maintaining conductivity.
- Statement (ii) is incorrect: Reference electrodes require a salt bridge for proper functioning in many setups.
- Statement (iii) is incorrect: Although the salt bridge minimizes the effect on test solution composition, it still contributes ions and hence has some effect.