The reference potential of a silver-silver chloride electrode is primarily determined by?

The reference potential of a silver-silver chloride electrode is fundamentally influenced by the concentration of the potassium chloride filling solution. This is because the electrode is based on the equilibrium established between metallic silver and silver chloride in the presence of chloride ions.

The potential of the silver-silver chloride electrode is determined by the Nernst equation, which accounts for the activity of the ions in solution. Since potassium chloride dissociates into potassium and chloride ions, the concentration of the chloride ions plays a crucial role in establishing and maintaining the electrode's potential. A higher concentration of KCl results in a more stable reference potential due to a consistent and predictable concentration of chloride ions.

In contrast, factors such as the surface area of the electrode and the concentration of silver in the paste, while they may influence the overall behavior of the electrode, do not primarily dictate its reference potential. The activity of total anion in the paste is also relevant, but it is the concentration of chloride that directly sets the potential of the silver-silver chloride system as it directly relates to the equilibrium established at the electrode interface. Hence, the correct answer is the concentration of the potassium chloride filling solution.