Standard Potential of the Silver Half-Cell

E^{\circ}(\mathrm{Ag^+}/\mathrm{Ag}) = 0.799\ \text{V}

Value	799 mV (0.799 V) Use in the calculator →
Status	Measured: ± 0.5 mV (6.3 × 10⁻⁴ relative)
Source	USGS PHREEQC 3 database minteq.v4.dat (MINTEQA2 version 4), the file the site's water pages use: Agmetal, Ag = Ag⁺ + e⁻, log K −13.5065 at 25 °C
Categories	Chemistry

Standard Potential of the Silver Half-Cell in every voltage unit

Unit	Value
millivolt	799 mV
volt	0.799 V
kilovolt	0.000799 kV
picovolt	799,000,000,000 pV
nanovolt	799,000,000 nV
microvolt	799,000 μV
megavolt	7.9900000e-07 MV
gigavolt	7.9900000e-10 GV

Learning zone

Silver's high standard potential makes it a noble metal that resists oxidation by air or water; what tarnishes it is sulfide, not oxygen. The half-cell's real importance is practical: coat a silver wire with AgCl and immerse it in saturated KCl and you have the Ag/AgCl reference electrode, at +0.197 V against the hydrogen electrode, which is the reference inside virtually every pH probe, ORP probe and ion-selective electrode in use today.

It is stable, cheap, non-toxic and works over a wide temperature range: all the things a hydrogen electrode is not. The same chemistry underlies the Mohr and Volhard titrations for chloride, and the silver-halide photography that dominated imaging for a century: a photon reduces a few Ag⁺ ions to metallic silver, forming a latent image that development then amplifies by a factor of around 10⁹.

Used by 2 solvers

Nernst Equation

E = E^{\circ} - \frac{RT}{nF}\ln Q

Standard Cell Potential from Half-Cells

E^{\circ}_{\text{cell}} = E^{\circ}_{\text{cathode}} - E^{\circ}_{\text{anode}}

Revised 1 November 2026

Cite this page

formula.expert. (2026, November 1). Standard Potential of the Silver Half-Cell. https://formula.expert/constants/standard-potential-silver