Reduction Half–Reaction Standard Potential, E° (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