What is the standard electrode potential (E°) of the Silver-Silver Chloride Electrode?

What is the standard electrode potential (E°) of the Silver-Silver Chloride Electrode?

• A. 0 V
• B. 0.197 V
• C. 0.242 V
• D. 0.100 V

Answer: (B)

The potential of the Silver-Silver Chloride electrode is set by the equilibrium of the AgCl solid with silver metal and chloride in solution: AgCl(s) + e− ⇌ Ag(s) + Cl−. The standard potential for this couple at 25 °C, with the chloride activity defined as standard (in practice, in a saturated KCl reference), is about +0.197 V versus the standard hydrogen electrode. This value reflects the balance between the solubility of AgCl and the chloride ion concentration in the reference solution. In other words, under standard conditions the Ag/AgCl electrode sits at roughly +0.20 V, which is why 0.197 V is the commonly cited standard potential. If the chloride activity changes, the potential shifts according to the Nernst equation, but under the usual standard conditions it’s about 0.197 V.

The potential of the Silver-Silver Chloride electrode is set by the equilibrium of the AgCl solid with silver metal and chloride in solution: AgCl(s) + e− ⇌ Ag(s) + Cl−. The standard potential for this couple at 25 °C, with the chloride activity defined as standard (in practice, in a saturated KCl reference), is about +0.197 V versus the standard hydrogen electrode. This value reflects the balance between the solubility of AgCl and the chloride ion concentration in the reference solution. In other words, under standard conditions the Ag/AgCl electrode sits at roughly +0.20 V, which is why 0.197 V is the commonly cited standard potential. If the chloride activity changes, the potential shifts according to the Nernst equation, but under the usual standard conditions it’s about 0.197 V.