Why potassium chloride is not used in saturated calomel electorde ?
Answers
The Saturated calomel electrode (SCE) is a reference electrode based on the reaction between elemental mercury and mercury(I) chloride. It has been widely replaced by the silver chloride electrode, however the calomel electrode has a reputation of being more robust. The aqueous phase in contact with the mercury and the mercury(I) chloride (Hg2Cl2, "calomel") is a saturated solution of potassium chloride in water. The electrode is normally linked via a porous frit to the solution in which the other electrode is immersed. This porous frit is a salt bridge.
In cell notation the electrode is written as:
Cl(4M) | Hg2Cl2 (s) | Hg (l) | Pt
Calomel electrode: This reference electrode consists of a mercury and mercury-chloride molecules. This electrode can be relatively easier to make and maintain compared to the SHE. It is composed of a solid paste of Hg2Cl2 and liquid elemental mercury attached to a rod that is immersed in a saturated KCl solution