Standard Potential of the Zinc Half-Cell
| Value | -762.8 mV (-0.7628 V) |
| Status | Measured: ± 0.5 mV (6.6 × 10⁻⁴ relative) |
| Source | USGS PHREEQC 3 database minteq.v4.dat (MINTEQA2 version 4), the file the site's water pages use: Znmetal, Zn = Zn²⁺ + 2e⁻, log K 25.7886 at 25 °C, so E° = −(2.302585 RT/2F) × 25.7886 |
| Categories | Chemistry |
| Unit | Value |
|---|---|
| millivolt | -762.8 mV |
| volt | -0.7628 V |
| kilovolt | -0.0007628 kV |
| picovolt | -762,800,000,000 pV |
| nanovolt | -762,800,000 nV |
| microvolt | -762,800 μV |
| megavolt | -7.6280000e-07 MV |
| gigavolt | -7.6280000e-10 GV |
Learning zone
Zinc's strongly negative potential means it would much rather be an ion than a metal, and that eagerness is the whole basis of corrosion protection. Bolt a zinc anode to a steel hull, a boat engine or a water heater and the zinc corrodes preferentially, holding the steel at a potential where iron dissolution simply cannot proceed. The anode is consumed and replaced on a schedule: that is the design, not a failure.
Paired with copper at +0.3386 V it gives the Daniell cell, E° = 1.10 V, built by John Frederic Daniell in 1836 as the first battery steady enough to run a telegraph line for hours. Galvanising works on the same principle with a twist: the zinc coating protects steel both as a physical barrier and electrochemically, so a scratch that exposes bare steel still does not rust, because the surrounding zinc keeps it cathodic.
Cite this page
formula.expert. (2026, November 1). Standard Potential of the Zinc Half-Cell. https://formula.expert/constants/standard-potential-zinc