Reduction Potentials

Standard Reduction Potentials
at 25 deg C (298 K) in aqueous solution

 

When a metal gains charge and gives up electrons, the metal acts as a reducing agent.

In the following, the more positive the potential, the more reducing ability the reaction has.

If a reaction is reversed, its potential gets multiplied by -1.

 

Reaction	Potential in V
F2 + 2 e- -> 2 F-	2.87
Ag2+ + e- -> Ag+	1.99
Co3+ + e- -> Co2+	1.95
H2O2 + 2 H+ + 2 e- -> 2 H2O	1.78
Ce4+ + e- -> Ce3+	1.70
PbO2 + 4 H+ + SO42- + 2 e- -> PbSO4 + 2 H2O	1.69
MnO4- + 4 H+ + 3 e- -> MnO2 + 2 H2O	1.68
2 e- + 2 H+ + IO4- -> IO3- + H2O	1.60
MnO4- + 8 H+ + 5 e- -> Mn2+ + 4 H2O	1.51
Au3+ + 3 e- -> Au	1.50
PbO2 + 4 H+ + 2 e- -> Pb2+ + 2 H2O	1.46
Cl2 + 2 e- -> 2 Cl-	1.36
Cr2O72- + 14 H+ + 6 e- -> 2 Cr3+ + 7 H2O	1.33
O2 + 4 H+ + 4 e- -> 2 H2O	1.23
MnO2 + 4 H+ + 2 e- -> Mn2+ + 2 H2O	1.21
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Reaction	Potential in V
IO3- + 6 H+ + 5 e- -> (1/2) I2 + 3 H2O	1.20
Br2 + 2 e- -> 2 Br-	1.09
VO2+ + 2 H+ + e- -> VO2+ + H2O	1.00
AuCl4- + 3 e- -> Au + 4 Cl-	0.99
NO3- + 4 H+ + 3 e- -> NO + 2 H2O	0.96
ClO2 + e- -> ClO2-	0.954
2 Hg2+ + 2 e- -> Hg22+	0.91
Ag+ + e- -> Ag	0.80
Hg22+ + 2 e- -> 2 Hg	0.80
Fe3+ + e- -> Fe2+	0.77
O2 + 2 H+ + 2 e- -> H2O2	0.68
MnO4- + e- -> MnO42-	0.56
I2 + 2 e- -> 2 I-	0.54
Cu+ + e- -> Cu	0.52
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Reaction	Potential in V
O2 + 2 H2O + 4 e- -> 4 OH-	0.40
Cu2+ + 2 e- -> Cu	0.34
Hg2Cl2 + 2 e- -> 2 Hg + 2 Cl-	0.34
AgCl + e- -> Ag + Cl-	0.22
SO42- + 4 H+ + 2 e- -> H2SO3 + H2O	0.20
Cu2+ + e- -> Cu+	0.16
2 H+ + 2 e- -> H2	0.00
Fe3+ + 3 e- -> Fe	-0.036
Pb2+ + 2 e- -> Pb	-0.13
Sn2+ + 2 e- -> Sn	-0.14
Ni2+ + 2 e- -> Ni	-0.23
PbSO4 + 2 e- -> Pb + SO42-	-0.35
Cd2+ + 2 e- -> Cd	-0.40
Fe2+ + 2 e- -> Fe	-0.44
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Reaction	Potential in V
Cr3+ + e- -> Cr2+	-0.50
Cr3+ + 3 e- -> Cr	-0.73
Zn2+ + 2 e- -> Zn	-0.76
2 H2O + 2 e- -> H2 + 2 OH-	-0.83
Mn2+ + 2 e- -> Mn	-1.18
Al3+ + 3 e- -> Al	-1.66
H2 + 2 e- -> 2 H-	-2.23
Mg2+ + 2 e- -> Mg	-2.37
La3+ + 3 e- -> La	-2.37
Na+ + e- -> Na	-2.71
Ca2+ + 2 e- -> Ca	-2.76
Ba2+ + 2 e- -> Ba	-2.90
K+ + e- -> K	-2.92
Li+ + e- -> Li	-3.05
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Reaction	Potential in V
Sc -> Sc3+ + 3 e-	2.08
Ti -> Ti2+ + 2 e-	1.63
V -> V2+ + 2 e-	1.2
Mn -> Mn2+ + 2 e-	1.18
Cr -> Cr2+ + 2 e-	0.91
Zn -> Zn2+ + 2 e-	0.76
Fe -> Fe2+ + 2 e-	0.44
Co -> Co2+ + 2 e-	0.28
Ni -> Ni2+ + 2 e-	0.25
Cu -> Cu2+ + 2 e-	-0.34
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Reference: pp.721, 830 "Chemistry" by Steven S. Zumdahl, D.C. Heath and Company, 1986 (ISBN=0-669-04529-2)