How would you determine the standard electrode potential of the system mg2+|mg?
by using a standard hydrogen electrode
the standard hydrogen electrode is one of several types of half cell that can be used as a reference electrode. the electrode consists of:
- h2 gas at 101kpa pressure in equilibrium with h+ ions of concentration 1 mol/dm³
- a platinum electrode covered with platinum black in contact with the h2 and h+
platinum black is finely divided platinum which allows close contact of h2 and h+ so that equilibrium is established quickly. the platinum electrode is inert so it does not take part in the reaction.
the standard electrode potential for all half cells are measured relative to the standard hydrogen electrode. the electrode potential of this electrode is very negligible so it can be considered zero.
so when you connect the mg/mg2+ half cell to a voltmeter and to this standard hydrogen electrode, you can determine the electrode potential of the mg/mg2+ half cell