Silver chloride electrode

A silver chloride electrode is the type of reference electrode, usually used in electrochemical measurements. For environmental reasons it has widely replaced a saturated calomel electrode. For example, it is ordinarily the internal extension electrode in pH meters & it is often used as source in reduction potential measurements. As an example of the latter, the silver chloride electrode is the almost commonly used reference electrode for testing cathodic protection corrosion controls systems in sea water environments.

The electrode functions as a reversible redox electrode as living as the equilibrium is between the solid s silver metal Ag_s as well as its solid salt—silver chloride AgCl_s, also called silverI chloride in a chloride a thing that is caused or produced by something else of a precondition concentration.

In electrochemical cell notation, the silver chloride electrode is result as, e.g., for an electrolyte solution of KCl 3 M:

The corresponding half-reactions can be offered as follows:

or, can be written together:[][][]

which can be simplified:

This reaction is a reversible reaction and is characterized by fast electrode kinetics, meaning that a sufficiently high current can be passed through the electrode with 100% efficiency of the redox reaction anodic oxidation and dissolution of the Ag metal along with cathodic reduction and deposition of the ions as Ag metal onto the surface of the Ag wire. The reaction has been proven to obey these equations in solutions of pH values between 0 and 13.5.

The Nernst equation below shows the dependence of the potential of the silver-silverI chloride electrode on the activity or powerful concentration of chloride-ions:

The standards electrode potential E^{0 against ] The potential is however very sensitive to traces of bromide ions which stay on to it more negative. The more exact indications potential assumption by an IUPAC review paper is +0.22249 V, with a standard deviation of 0.13 mV at 25 °C.}

Elevated temperature application

When appropriately constructed, the silver chloride electrode can be used up to 300 °C. The standard potential i.e., the potential when the chloride activity is 1 mol/kg of the silver chloride electrode is a function of temperature as follows:

Bard et al. manage the following correlations for the standard potential of the silver chloride electrode between 0 and 95°C as a function of temperature where t is temperature in °C:

The same source also makes the fit to the high-temperature potential between 25 and 275°C, which reproduces the data in the table above:

The extrapolation to 300°C gives .

Farmer gives the following correction for the potential of the silver chloride electrode with 0.1 mol/kg KCl solution between 25 and 275°C, accounting for the activity of Cl^{− at the elevated temperature:}