Question

In a saturated calomel electrode, the saturation is with respect to

• A. KCl
• B. Hg2Cl2
• C. HgCl2
• D. AgCl

Hint:

A saturated calomel electrode is saturated with potassium chloride (KCl) and uses mercury(I) chloride (Hg2Cl2) as the redox couple.

Answer 1

The Correct Option is A, B

The saturated calomel electrode (SCE) is a type of reference electrode commonly used in electrochemical experiments. Understanding the components and functioning of the electrode is essential to know with respect to what it is saturated.

Components of a Saturated Calomel Electrode:

• Mercury (Hg): Present as the inner reference substance.
• Mercurous Chloride (Hg₂Cl₂): Also known as calomel, this is used in a paste form along with mercury.
• Potassium Chloride (KCl): The solution is saturated with KCl to maintain a consistent concentration of chloride ions.

Explanation:

The saturation is done with respect to both KCl and Hg₂Cl₂:

1. KCl: Saturating the solution with KCl ensures the concentration of chloride ions remains constant, which stabilizes the electrode potential of the SCE. The high concentration minimizes changes in the liquid junction potential when the electrode is used.
2. Hg₂Cl₂ (Calomel): This ensures that the electrode is in equilibrium with its own ions in the saturated solution, allowing the development of a stable and predictable electrode potential.

Thus, the correct answer options are KCl and Hg₂Cl₂, as these are the substances with respect to which the electrode solution is saturated to maintain its standard potential.