The standard electrode potential of Mg²⁺ | Mg can be measured with respect to the standard hydrogen electrode, represented by Pt_(s), H₂(g)(1 atm)| H⁺(aq)(1M).

A cell, consisting of Mg | MgSO₄(aq, 1M) as the anode and the standard hydrogen electrode as the cathode, is set up.

Mg|Mg²⁺ (aq, 1M)||H⁺ (aq, 1M)|H₂(g, 1 bar), P_(t)

Then, the emf of the cell is measured and this measured emf is the standard electrode potential of the magnesium electrode.

\(E^{\ominus} = E^{\ominus}_R - E^{\ominus}_L\)

Here, \( E^{\ominus}_R\) for the standard hydrogen electrode is zero.

∴ \(E^{\ominus} = 0 - E^{\ominus}_L\)

= \(- E^{\ominus}_L\)