calomel electrode

chemistry

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June 22, 2026

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The calomel electrode is a type of reference electrode used in chemistry. It is constructed using mercury, calomel (Hg₂Cl₂), and a potassium chloride solution. Calomel itself is a heavy, soft, white mineral formed from altered mercury minerals.12

Historically, calomel was widely used as a cathartic in medicine, but its use declined due to toxicity concerns related to mercury dissociation. While its medicinal applications have diminished, calomel still finds use in certain insecticides and fungicides. The calomel electrode, however, remains a valuable tool in chemical techniques like potentiometric titration, which measures electrical potential in electrolyte solutions.2

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acid–base reaction
Dissociation constants in aqueous solution
…a reference electrode, commonly the calomel electrode, serves to measure the actual hydrogen ion concentration, or the pH, of the solution. If E is the electromotive force (in volts) observed by the electrode, the equation giving the pH is as follows:
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…a reference electrode, commonly the calomel electrode, serves to measure the actual hydrogen ion concentration, or the pH, of the solution. If E is the electromotive force (in volts) observed by the electrode, the equation giving the pH is as follows:
Read More