School Science Lessons
Updated: 2007-12-16
Standard electrode potential, electrode potential, reduction potential, E⁰
The following list show the standard electrode potentials of half-reactions 1.0 molar solutions of some metals at 25^oC compared to the hydrogen half-reaction with electrode potential assumed to be zero.
A negative vale for E⁰ shows a poorer electron attracting ability than in the hydrogen half-cell. For a cell with the following half-cell reactions:
Ag⁺ (aq) + e^- --> Ag(s) +0.80 V, and Zn²⁺ (aq) + 2e^- --> Zn(s) -0.76 V,
the E⁰ value = (higher value - lower value)
= [(+0.80)  - (-0.76) = 1.56 V].
Half-reaction and E⁰ in volts, V
Li⁺ (aq) + e^-  -->  Li(s) -3.04 V
K⁺ (aq) + e^-  -->  K(s) -2.92 V
Ba²⁺ (aq) + 2e^-  -->  Ba(s) -2.91 V
Ca²⁺ (aq) + 2e^- --> Ca(s) -2.76 V
Na⁺ (aq) + e^- --> Na(s) -2.71 V
Mg²⁺ (aq) + 2e^- --> Mg(s) -2.38 V
Al³⁺ (aq) + 3e^- --> Al(s) -1.66 V
2H₂O(l) + 2e^- --> H₂(g) + 2OH^- (aq) -0.83 V
Zn²⁺ (aq) + 2e^- --> Zn(s) -0.76 V
Cr³⁺ (aq) + 3e^- --> Cr(s) -0.74 V
Fe²⁺ (aq) + 2e^- --> Fe(s) -0.41 V
Cd²⁺ (aq) + 2e^- --> Cd(s) -0.40 V
Cr³⁺ (aq) + e^- --> Cr²⁺ (aq) -0.42 V
Ni²⁺ (aq) + 2e^- --> Ni(s) -0.23 V
Sn²⁺ (aq) + 2e^- --> Sn(s) -0.14 V
Pb²⁺ (aq) + 2e^- --> Pb(s) -0.13 V
Fe³⁺ (aq) + 3e^- --> Fe(s) -0.04 V
2H⁺ (aq) + 2e^- --> H₂(g) 0.00 V <-----Hydrogen
Sn⁴⁺ (aq) + 2e^- --> Sn²⁺ (aq) +0.15 V
Cu²⁺ (aq) + e^- --> Cu⁺ (aq) +0.16 V
Bi³⁺ (aq) + 3e^- --> Bi(s) +0.32 V
Cu²⁺ (aq) + 2e^- --> Cu(s) +0.34 V
Cu⁺ (aq) + e^- --> Cu(s) +0.52 V
I₂(s) + 2e^- --> 2I^- (aq) +0.54 V
Fe³⁺ (aq) + e^- --> Fe²⁺ (aq) +0.77 V
Ag⁺ (aq) + e^- --> Ag(s) +0.80 V
Hg²⁺ (aq) + 2e^- --> Hg(l) +0.85 V
2Hg²⁺ (aq) + 2e^- --> Hg₂²⁺ (aq) +0.91 V
NO₃^- (aq) + 4H⁺ (aq) + 3e^- --> NO(g) + 2H₂O(l) +0.96 V
O₂(g) + 4H⁺ (aq) + 4e^- --> 2H₂O(l) +1.23 V
Cr₂O₇^2- (aq) + 14H⁺ (aq) + 6e^- --> 2Cr³⁺ (aq) + 7H₂O(l) +1.33 V
MnO₄^- (aq) + 8H⁺ (aq) + 5e^- --> Mn²⁺ (aq) + 4H₂O(l) +1.49 V
Pb⁴⁺ (aq) + 2e^- --> Pb²⁺ (aq) +1.69 V
H₂O₂ (aq) + 2H⁺ (aq) + 2e^- --> 2H₂O(l) +1.78 V
O₃(g) + 2H⁺ (aq) + 2e^- --> O₂(g) + H₂O(l) +2.07 V

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