3 3)
represented by Pt(s)ú H2(g)ú H+(aq), is assigned
a zero potential at all temperatures
corresponding to the reaction
    H+ (aq) + e–  ®  1
2 H2(g)
The standard hydrogen electrode consists
of a platinum electrode coated with platinum
black The electrode is dipped in an acidic
solution and pure hydrogen gas is bubbled
through it The concentration of both the
reduced and oxidised forms of hydrogen is
maintained at unity (Fig