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Reduction Potentials

rename
Updated 2009-03-26 23:21

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.

 

ReactionPotential 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 H2O1.78
Ce4+ + e- -> Ce3+1.70
PbO2 + 4 H+ + SO42- + 2 e- -> PbSO4 + 2 H2O1.69
MnO4- + 4 H+ + 3 e- -> MnO2 + 2 H2O1.68
2 e- + 2 H+ + IO4- -> IO3- + H2O1.60
MnO4- + 8 H+ + 5 e- -> Mn2+ + 4 H2O1.51
Au3+ + 3 e- -> Au1.50
PbO2 + 4 H+ + 2 e- -> Pb2+ + 2 H2O1.46
Cl2 + 2 e- -> 2 Cl-1.36
Cr2O72- + 14 H+ + 6 e- -> 2 Cr3+ + 7 H2O1.33
O2 + 4 H+ + 4 e- -> 2 H2O1.23
MnO2 + 4 H+ + 2 e- -> Mn2+ + 2 H2O1.21
memorize

 

ReactionPotential in V
IO3- + 6 H+ + 5 e- -> (1/2) I2 + 3 H2O1.20
Br2 + 2 e- -> 2 Br- 1.09
VO2+ + 2 H+ + e- -> VO2+ + H2O1.00
AuCl4- + 3 e- -> Au + 4 Cl-0.99
NO3- + 4 H+ + 3 e- -> NO + 2 H2O0.96
ClO2 + e- -> ClO2-0.954
2 Hg2+ + 2 e- -> Hg22+0.91
Ag+ + e- -> Ag0.80
Hg22+ + 2 e- -> 2 Hg0.80
Fe3+ + e- -> Fe2+0.77
O2 + 2 H+ + 2 e- -> H2O20.68
MnO4- + e- -> MnO42-0.56
I2 + 2 e- -> 2 I-0.54
Cu+ + e- -> Cu0.52
memorize

 

ReactionPotential in V
O2 + 2 H2O + 4 e- -> 4 OH-0.40
Cu2+ + 2 e- -> Cu0.34
Hg2Cl2 + 2 e- -> 2 Hg + 2 Cl-0.34
AgCl + e- -> Ag + Cl-0.22
SO42- + 4 H+ + 2 e- -> H2SO3 + H2O0.20
Cu2+ + e- -> Cu+0.16
2 H+ + 2 e- -> H20.00
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
memorize

 

ReactionPotential 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
memorize

 

ReactionPotential 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
memorize

 

Reference: pp.721, 830 "Chemistry" by Steven S. Zumdahl, D.C. Heath and Company, 1986 (ISBN=0-669-04529-2)