Question

The potential of the calomel electrode depends upon

• A. Concentration of mercuric chloride
• B. Concentration of mercury
• C. The concentration of potassium chloride solution
• D. Membrane

Answer 1

The Correct Option is C

The calomel electrode is a type of reference electrode traditionally used in electrochemical cells. This electrode's potential primarily depends on the concentration of the potassium chloride solution present in it. Let's explore why this is the case and why the other options are not relevant:

1. Understanding the Calomel Electrode:
   • The calomel electrode consists of mercury and mercurous chloride (Hg₂Cl₂), termed as calomel, in a paste with potassium chloride (KCl). The setup involves a mercury pool, which is in contact with a paste of calomel and KCl.
2. Factors affecting the potential of the Calomel Electrode:
   • The primary factor is the concentration of the potassium chloride solution because it determines the ionic strength and activity of the chloride ions in the system.
   • Concentration of mercuric chloride does not have a role here, as mercuric chloride is not a component in the setup.
   • The concentration of mercury does not vary as it is in the solid state and contributes a constant potential.
   • Membrane is irrelevant, as the calomel electrode functions without a separating membrane.
3. Conclusion:
   • Thus, the correct choice is "The concentration of potassium chloride solution" because it directly influences the electrochemical potential of the calomel electrode through the activity of chloride ions.

Thus, the correct answer is The concentration of potassium chloride solution.