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Standard Electrode (Reduction) Potentials in Aqueous Solution at 25 oC





Reduction Half–Reaction
Standard Potential, Eo(V)
Acid Solution

F2(g) + 2 e 2 F(aq)
2.86
OF2(g) + 2 H+ (aq) + 4 e H2O(l) + 2 F(aq)
2.1
O3(g) + 2 H+ (aq) + 2 e O2(g) + H2O(l)
2.075
S2O82– (aq) + 2 e 2 SO42–(aq)
2.01
Ag2+(aq) + e Ag+(aq)
1.98
Co3+(aq) + e Co2+(aq)
1.82
H2O2(aq) + 2 H+(aq) + 2 e 2 H2O(l)
1.763
MnO4(aq ) + 4 H+(aq) + 3 e MnO2(s) + 2 H2O(l)
1.70
PbO2(s) + SO4 2–(aq) + 4 H+(aq) + 2 e PbSO4(s) + 2 H2O(l)
1.69
Au3+(aq) + 3 e Au(s)
1.52
MnO4(aq ) + 8 H+(aq) + 5 e Mn2+(aq) + 4 H2O(l)
1.51
2 BrO3 (aq) + 12 H+(aq) + 10 e Br2(l) + 6 H2O(l)
1.478
PbO2(s) + 4 H+ (aq) + 2 e Pb2+(aq) + 2 H2O(l)
1.455
ClO3 (aq) + 6 H+(aq) + 6 e Cl(aq) + 3 H2O(l)
1.450
Ce4+(aq) + e Ce3+(aq)
1.44
Au3+(aq) + 2 e Au+(aq)
1.36
Cl2(g) + 2 e 2 Cl(aq)
1.358
Cr2O72– (aq) + 14 H+(aq) + 6 e 2 Cr3+(aq) + 7 H2O(l)
1.33
MnO2(s) + 4 H+ (aq) + 2 e Mn2+(aq) + 2 H2O(l)
1.23
O2(g) + 4 H+ (aq) + 4 e 2 H2O(l)
1.229
2 IO3 (aq) + 12 H+(aq) + 10 e I2(s) + 6 H2O(l)
1.20
ClO4 (aq) + 2 H+(aq) + 2 e ClO3(aq) + H2O( l)
1.19
ClO3 (aq) + 2 H+(aq) + e ClO2(g) + H2O(l)
1.175
NO2(g) + H+ (aq) + e HNO2(aq)
1.07
Br2(l) + 2 e 2 Br(aq)
1.065
NO2(g) + 2 H+ (aq) + 2 e NO(g) + H2O(l)
1.03
[AuCl4] (aq) + 3 e Au(s) + 4 Cl(aq)
1.002
VO2+(aq ) + 2 H+(aq) + e VO2+(aq) + H2O(l)
1.000
NO3(aq ) + 4 H+(aq) + 3 e NO(g) + 2 H2O(l)
0.956
2 Hg2+(aq) + 2 e Hg22+(aq)
0.90
Cu2+(aq) + I(aq) + e CuI(s)
0.86
Hg2+(aq) + 2 e Hg(l)
0.854
Ag+(aq) + e Ag(s)
0.800
Hg22+(aq) + 2 e 2 Hg(l)
0.80
Fe3+(aq) + e Fe2+(aq)
0.771
O2(g) + 2 H+ (aq) + 2 e H2O2(aq)
0.695
2 HgCl2(s) + 2 e Hg2Cl2(s) + 2 Cl( aq)
0.63
MnO4(aq ) + e MnO42–(aq)
0.56
I2(s) + 2 e 2 I(aq)
0.535
Cu+(aq) + e Cu(s)
0.520
H2SO3(aq) + 4 H+(aq) + 4 e S(s) + 3 H2O(l)
0.449
C2N2(g) + 2 H+(aq) + 2e 2 HCN(aq)
0.37
[Fe(CN)6]3–(aq) + e [Fe(CN)6]4–(aq)
0.361
Cu2+(aq) + 2 e Cu(s)
0.340
VO2+(aq) + 2 H +(aq) + e V3+(aq) + H2O(l)
0.337
PbO2(s) + 2 H+ (aq) + 2 e PbO(s) + H2O(l)
0.28
HgCl2(s) + 2 e Hg(l) + 2 Cl(aq)
0.2676
HAsO2(aq) + 3 H+ (aq) + 3 e As(s) + 2 H2O(l)
0.240
AgCl(s) + e Ag(s) + Cl(aq)
0.2223
SO42–(aq ) + 4 H+(aq) + 2 e SO2(g) + 2 H2O(l)
0.17
Cu2+(aq) + e Cu+(aq)
0.159
Sn4+(aq) + 2 e Sn2+(aq)
0.154
S(s) + 2 H+(aq ) + 2 e H2S(g)
0.14
AgBr(s) + e Ag(s) + Br(aq)
0.071
2 H+(aq) + 2 e H2(g)
0.00
Fe3+(aq) + 3 e Fe(s)
–0.04
Pb2+(aq) + 2 e Pb(s)
–0.125
Sn2+(aq) + 2 e Sn(s)
–0.137
AgI(s) + e Ag(s) + I(aq)
–0.152
V3+(aq) + e V2+(aq)
–0.255
Ni2+(aq) + 2 e Ni(s)
–0.257
H3PO4(aq) + 2 H+(aq) + 2 e H3PO3(aq) + H2O(l)
–0.276
Co2+(aq) + 2 e Co(s)
–0.277
PbSO4(s) + 2 e Pb(s) + SO42–(aq)
–0.356
Cd2+(aq) + 2 e Cd(s)
–0.403
Cr3+(aq) + e Cr2+(aq)
–0.424
Fe2+(aq) + 2 e Fe(s)
–0.440
2 CO2(g) + 2 H+ (aq) + 2 e H2C2O4(aq)
–0.49
Cr3+(aq) + 3 e Cr(s)
–0.74
Zn2+(aq) + 2 e Zn(s)
–0.763
Cr2+(aq) + 2 e Cr(s)
–0.90
Mn2+(aq) + 2 e Mn(s)
–1.18
Ti2+(aq) + 2 e Ti(s)
–1.63
U3+(aq) + 3 e U(s)
–1.66
Al3+(aq) + 3 e Al(s)
–1.676
Mg2+(aq) + 2 e Mg(s)
–2.356
Na+(aq) + e Na(s)
–2.713
Ca2+(aq) + 2 e Ca(s)
–2.84
Sr2+(aq) + 2 e Sr(s)
–2.89
Ba2+(aq) + 2 e Ba(s)
–2.92
Cs+(aq) + e Cs(s)
–2.923
K+(aq) + e K(s)
–2.924
Rb+(aq) + e Rb(s)
–2.924
Li+(aq) + e Li(s)
–3.04
Basic Solution
O3(g) + H2O(l) + 2 e O2(g) + 2 OH(aq)
1.246
ClO(aq) + H 2O(l) + 2 e Cl(aq) + 2 OH(aq)
0.890
HO2 (aq) + H2O(l) + 2 e 3 OH(aq)
0.88
BrO(aq) + H 2O(l) + 2 e Br(aq) + 2 OH(aq )
0.766
ClO3(aq ) + 3 H2O(l) + 6 e Cl(aq) + 6 OH(aq)
0.622
2 AgO(s) + H2O(l ) +2 e Ag2O(s) + 2 OH(aq)
0.604
MnO4(aq ) + 2 H2O(l) + 3 e MnO2(s) + 4 OH(aq)
0.60
ClO2(aq ) + H2O(l) + 2 e ClO(aq) + 2 OH(aq)
0.59
BrO3(aq ) + 3 H2O(l) + 6 e Br(aq) + 6 OH(aq)
0.584
IO(aq) + H 2O(l) + 2 e I(aq) + 2 OH(aq)
0.49
Ni(OH)3(s) + e Ni(OH)2(s) + OH(aq)
0.48
BrO(aq) + 2 H 2O(l) + 2 e Br2(l) + 4 OH(aq)
0.455
IO(aq) + 2 H 2O(l) + 2 e I2(s) + 4 OH(aq)
0.42
O2(g) + 2 H2 O(l) + 4 e 4 OH(aq)
0.401
ClO3(aq ) + H2O(l) + 2 e ClO2(aq) + 2 OH(aq )
0.35
Ag2O(s) + H2 O(l) + 2 e 2 Ag(s) + 2 OH(aq)
0.342
Co(OH)3(s) + e Co(OH)2(s) + OH(aq)
0.17
ClO4(aq ) + H2O(l) + 2 e ClO3(aq) + 2 OH(aq )
0.17
NO3(aq ) + H2O(l) + 2 e NO2(aq) +2 OH(aq )
0.01
CrO42–( aq) + 4 H2O(l) + 3 e [Cr(OH)4](aq) + 4 OH (aq)
–0.13
HPbO2 (aq) + H2O(l) + 2 e Pb(s) + 3 OH(aq)
–0.54
CH2O(aq) + 2 H2O(l) + 2 e CH3OH(aq) + 2 OH(aq)
–0.59
SO32–(aq ) + 3 H2O(l) + 4 e S(s) + 6 OH(aq)
–0.66
AsO43–( aq) + 2 H2O(l) + 2 e AsO2(aq) + 4 OH(aq )
–0.67
AsO2(aq ) + 2 H2O(l) + 3 e As(s) + 4 OH(aq)
–0.68
2 H2O(l) + 2 e H2(g) + 2 OH(aq)
–0.828
OCN(aq ) + H2O(l) + 2 e CN(aq) + 2 OH (aq)
–0.97
As(s) + 3 H2O(l ) + 3 e AsH3(g) + 3 OH(aq)
–1.21
[Zn(OH)4]2– (aq) + 2 e Zn(s) + 4 OH(aq)
–1.285
Sb(s) + 3 H2O(l ) + 3 e SbH3(g) + 3 OH(aq)
–1.338
[Al(OH)4] (aq) + 3 e Al(s) + 4 OH(aq)
–2.310
Mg(OH)2(s) + 2 e Mg(s) + 2 OH(aq)
–2.687