Standard Potential of the Zinc Half-Cell
| Value | -0.7618 V |
| Status | Measured: ± 0.0005 V (0.00066 relative) |
| Source | CRC Handbook |
| Categories | Chemistryelectrochemistry |
| microvolt | -761,800 μV |
| millivolt | -761.8 mV |
| volt | -0.7618 V |
| kilovolt | -0.0007618 kV |
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 +0.3419 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.