Standard Electrode Potentials in Aqueous Solution at 25°C

Cathode (Reduction)
Half-Reaction
Standard Potential
E° (volts)
Li+(aq) + e- Li(s)
-3.04
K+(aq) + e- K(s)
-2.92
Ca2+(aq) + 2e- Ca(s)
-2.76
Na+(aq) + e- Na(s)
-2.71
Mg2+(aq) + 2e- Mg(s)
-2.38
Al3+(aq) + 3e- Al(s)
-1.66
2H2O(l) + 2e- H2(g) + 2OH-(aq)
-0.83
Zn2+(aq) + 2e- Zn(s)
-0.76
Cr3+(aq) + 3e- Cr(s)
-0.74
Fe2+(aq) + 2e- Fe(s)
-0.41
Cd2+(aq) + 2e- Cd(s)
-0.40
Ni2+(aq) + 2e- Ni(s)
-0.23
Sn2+(aq) + 2e- Sn(s)
-0.14
Pb2+(aq) + 2e- Pb(s)
-0.13
Fe3+(aq) + 3e- Fe(s)
-0.04
2H+(aq) + 2e- H2(g)
 0.00
S4O62-(aq) + 2e- 2S2O32-(g)
 +0.08
Sn4+(aq) + 2e- Sn2+(aq)
+0.15
Cu2+(aq) + e- Cu+(aq)
+0.16
ClO4-(aq) + H2O(l) + 2e- ClO3-(aq) + 2OH-(aq)
+0.17
SO42-(aq) + 4H+ + 2e H2SO3(aq) + H2O
+0.17
AgCl(s) + e- Ag(s) + Cl-(aq)
+0.22
Cu2+(aq) + 2e- Cu(s)
+0.34
ClO3-(aq) + H2O(l) + 2e- ClO2-(aq) + 2OH-(aq)
+0.35
IO-(aq) + H2O(l) + 2e- I-(aq) + 2OH-(aq)
+0.49
Cu+(aq) + e- Cu(s)
+0.52
I2(s) + 2e- 2I-(aq) +0.54
ClO2-(aq) + H2O(l) + 2e- ClO-(aq) + 2OH-(aq)
+0.59
Fe3+(aq) + e- Fe2+(aq)
+0.77
Hg22+(aq) + 2e- 2Hg(l)
+0.80
Ag+(aq) + e- Ag(s)
+0.80
Hg2+(aq) + 2e- Hg(l)
+0.85
ClO-(aq) + H2O(l) + 2e- Cl-(aq) + 2OH-(aq)
+0.90
2Hg2+(aq) + 2e- Hg22+(aq)
+0.90
NO3-(aq) + 4H+(aq) + 3e- NO(g) + 2H2O(l)
+0.96
Br2(l) + 2e- 2Br-(aq)
+1.07
O2(g) + 4H+(aq) + 4e- 2H2O(l)
+1.23
Cr2O72-(aq) + 14H+(aq) + 6e- 2Cr3+(aq) + 7H2O(l)
+1.33
Cl2(g) + 2e- 2Cl-(aq)
+1.36
Ce4+(aq) + e- Ce3+(aq)
+1.44
MnO4-(aq) + 8H+(aq) + 5e- Mn2+(aq) + 4H2O(l)
+1.49
H2O2(aq) + 2H+(aq) + 2e- 2H2O(l)
+1.78
Co3+(aq) + e- Co2+(aq)
+1.82
S2O82-(aq) + 2e- 2SO42-(aq)
+2.01
O3(g) + 2H+(aq) + 2e- O2(g) + H2O(l)
+2.07
F2(g) + 2e- 2F-(aq)
+2.87