Electrochemical series

ELECTROCHEMICAL SERIES
Petr Vanýsek
There are three tables for this electrochemical series. Each table
lists standard reduction potentials, E° values, at 298.15 K (25 °C),
and at a pressure of 101.325 kPa (1 atm). Table 1 is an alphabetical
listing of the elements, according to the symbol of the elements.
Thus, data for silver (Ag) precede those for aluminum (Al). Table
2 lists only those reduction reactions that have E° values posi-
tive in respect to the standard hydrogen electrode. In Table 2, the
reactions are listed in the order of increasing positive potential,
and they range from 0.0000 V to + 3.4 V. Table 3 lists only those
reduction potentials which have E° negative with respect to the
standard hydrogen electrode. In Table 3, the reactions are listed
in the order of decreasing potential and range from 0.0000 V to
–4.10 V. The reliability of the potentials is not the same for all the
data. Typically, the values with fewer significant figures have lower
reliability. The values of reduction potentials, in particular those
of less common reactions, are not definite; they are subject to oc-
casional revisions.
Abbreviations: ac = acetate; bipy = 2,2´-dipyridine, or bipyridine;
en = ethylenediamine; phen = 1,10-phenanthroline.
References
1. Milazzo, G., Caroli, S., and Sharma, V. K. Tables of Standard Electrode
Potentials, Wiley, Chichester, 1978.
2. Bard, A. J., Parsons, R., and Jordan, J. Standard Potentials in Aqueous
Solutions, Marcel Dekker, New York, 1985.
3. Bratsch, S. G. J. Phys. Chem. Ref. Data, 18, 1–21, 1989.
Reaction E°/V
Ac3+
+ 3 e Ac –2.20
Ag+
+ e Ag 0.7996
Ag2+
+ e Ag+
1.980
Ag(ac) + e Ag + (ac)–
0.643
AgBr + e Ag + Br–
0.07133
AgBrO3
+ e Ag + BrO3
–
0.546
Ag2
C2
O4
+ 2 e 2 Ag + C2
O4
2–
0.4647
AgCl + e Ag + Cl–
0.22233
AgCN + e Ag + CN–
–0.017
Ag2
CO3
+ 2 e 2 Ag + CO3
2–
0.47
Ag2
CrO4
+ 2 e 2 Ag + CrO4
2–
0.4470
AgF + e Ag + F–
0.779
Ag4
[Fe(CN)6
] + 4 e 4 Ag + [Fe(CN)6
]4–
0.1478
AgI + e Ag + I–
–0.15224
AgIO3
+ e Ag + IO3
–
0.354
Ag2
MoO4
+ 2 e 2 Ag + MoO4
2–
0.4573
AgNO2
+ e Ag + 2 NO2
–
0.564
Ag2
O + H2
O + 2 e 2 Ag + 2 OH–
0.342
Ag2
O3
+ H2
O + 2 e 2 AgO + 2 OH–
0.739
Ag3+
+ 2 e Ag+
1.9
Ag3+
+ e Ag2+
1.8
Ag2
O2
+ 4 H+
+ e 2 Ag + 2 H2
O 1.802
2 AgO + H2
O + 2 e Ag2
O + 2 OH–
0.607
AgOCN + e Ag + OCN–
0.41
Ag2
S + 2 e 2 Ag + S2–
–0.691
Ag2
S + 2 H+
+ 2 e 2 Ag + H2
S –0.0366
AgSCN + e Ag + SCN–
0.08951
Ag2
SeO3
+ 2 e 2 Ag + SeO4
2–
0.3629
Ag2
SO4
+ 2 e 2 Ag + SO4
2–
0.654
Ag2
WO4
+ 2 e 2 Ag + WO4
2–
0.4660
Al3+
+ 3 e Al –1.662
Al(OH)3
+ 3 e Al + 3 OH–
–2.31
Al(OH)4
–
+ 3 e Al + 4 OH–
–2.328
H2
AlO3
–
+ H2
O + 3 e Al + 4 OH–
–2.33
AlF6
3–
+ 3 e Al + 6 F–
–2.069
Am4+
+ e Am3+
2.60
Am2+
+ 2 e Am –1.9
Am3+
+ 3 e Am –2.048
Am3+
+ e Am2+
–2.3
Reaction E°/V
As + 3 H+
+ 3 e AsH3
–0.608
As2
O3
+ 6 H+
+ 6 e 2 As + 3 H2
O 0.234
HAsO2
+ 3 H+
+ 3 e As + 2 H2
O 0.248
AsO2
–
+ 2 H2
O + 3 e As + 4 OH–
–0.68
H3
AsO4
+ 2 H+
+ 2 e–
HAsO2
+ 2 H2
O 0.560
AsO4
3–
+ 2 H2
O + 2 e AsO2
–
+ 4 OH–
–0.71
At2
+ 2 e 2 At–
0.3
Au+
+ e Au 1.692
Au3+
+ 2 e Au+
1.401
Au3+
+ 3 e Au 1.498
Au2+
+ e –
Au+
1.8
AuOH2+
+ H+
+ 2 e Au+
+ H2
O 1.32
AuBr2
–
+ e Au + 2 Br–
0.959
AuBr4
–
+ 3 e Au + 4 Br–
0.854
AuCl4
–
+ 3 e Au + 4 Cl–
1.002
Au(OH)3
+ 3 H+
+ 3 e Au + 3 H2
O 1.45
H2
BO3
–
+ 5 H2
O + 8 e BH4
–
+ 8 OH–
–1.24
H2
BO3
–
+ H2
O + 3 e B + 4 OH–
–1.79
H3
BO3
+ 3 H+
+ 3 e B + 3 H2
O –0.8698
B(OH)3
+ 7 H+
+ 8 e BH4
–
+ 3 H2
O –0.481
Ba2+
+ 2 e Ba –2.912
Ba2+
+ 2 e Ba(Hg) –1.570
Ba(OH)2
+ 2 e Ba + 2 OH–
–2.99
Be2+
+ 2 e Be –1.847
Be2
O3
2–
+ 3 H2
O + 4 e 2 Be + 6 OH–
–2.63
p–benzoquinone + 2 H+
+ 2 e
hydroquinone
0.6992
Bi+
+ e Bi 0.5
Bi3+
+ 3 e Bi 0.308
Bi3+
+ 2 e Bi+
0.2
Bi + 3 H+
+ 3 e BiH3
–0.8
BiCl4
–
+ 3 e Bi + 4 Cl–
0.16
Bi2
O3
+ 3 H2
O + 6 e 2 Bi + 6 OH–
–0.46
Bi2
O4
+ 4 H+
+ 2 e 2 BiO+
+ 2 H2
O 1.593
BiO+
+ 2 H+
+ 3 e Bi + H2
O 0.320
BiOCl + 2 H+
+ 3 e Bi + Cl–
+ H2
O 0.1583
Bk4+
+ e Bk3+
1.67
Bk2+
+ 2 e Bk –1.6
Bk3+
+ e Bk2+
–2.8
TABLE 1. Alphabetical Listing
8-20

Reaction E°/V
Br2
(aq) + 2 e 2 Br–
1.0873
Br2
(l) + 2 e 2 Br–
1.066
HBrO + H+
+ 2 e Br–
+ H2
O 1.331
HBrO + H+
+ e 1/2 Br2
(aq) + H2
O 1.574
HBrO + H+
+ e 1/2 Br2
(l) + H2
O 1.596
BrO–
+ H2
O + 2 e Br–
+ 2 OH–
0.761
BrO3
–
+ 6 H+
+ 5 e 1/2 Br2
+ 3 H2
O 1.482
BrO3
–
+ 6 H+
+ 6 e Br–
+ 3 H2
O 1.423
BrO3
–
+ 3 H2
O + 6 e Br–
+ 6 OH–
0.61
(CN)2
+ 2 H+
+ 2 e 2 HCN 0.373
2 HCNO + 2 H+
+ 2 e (CN)2
+ 2 H2
O 0.330
(CNS)2
+ 2 e 2 CNS–
0.77
CO2
+ 2 H+
+ 2 e HCOOH –0.199
Ca+
+ e Ca –3.80
Ca2+
+ 2 e Ca –2.868
Ca(OH)2
+ 2 e Ca + 2 OH–
–3.02
Calomel electrode, 1 molal KCl 0.2800
Calomel electrode, 1 molar KCl (NCE) 0.2801
Calomel electrode, 0.1 molar KCl 0.3337
Calomel electrode, saturated KCl (SCE) 0.2412
Calomel electrode, saturated NaCl (SSCE) 0.2360
Cd2+
+ 2 e Cd –0.4030
Cd2+
+ 2 e Cd(Hg) –0.3521
Cd(OH)2
+ 2 e Cd(Hg) + 2 OH–
–0.809
CdSO4
+ 2 e Cd + SO4
2–
–0.246
Cd(OH)4
2–
+ 2 e Cd + 4 OH–
–0.658
CdO + H2
O + 2 e Cd + 2 OH–
–0.783
Ce3+
+ 3 e Ce –2.336
Ce3+
+ 3 e Ce(Hg) –1.4373
Ce4+
+ e Ce3+
1.72
CeOH3+
+ H+
+ e Ce3+
+ H2
O 1.715
Cf4+
+ e Cf3+
3.3
Cf3+
+ e Cf2+
–1.6
Cf3+
+ 3 e Cf –1.94
Cf2+
+ 2 e Cf –2.12
Cl2
(g) + 2 e 2 Cl–
1.35827
HClO + H +
+ e 1/2 Cl2
+ H2
O 1.611
HClO + H+
+ 2 e Cl–
+ H2
O 1.482
ClO–
+ H2
O + 2 e Cl–
+ 2 OH–
0.81
ClO2
+ H+
+ e HClO2
1.277
HClO2
+ 2 H+
+ 2 e HClO + H2
O 1.645
HClO2
+ 3 H+
+ 3 e 1/2 Cl2
+ 2 H2
O 1.628
HClO2
+ 3 H+
+ 4 e Cl–
+ 2 H2
O 1.570
ClO2
–
+ H2
O + 2 e ClO–
+ 2 OH–
0.66
ClO2
–
+ 2 H2
O + 4 e Cl–
+ 4 OH–
0.76
ClO2
(aq) + e ClO2
–
0.954
ClO3
–
+ 2 H+
+ e ClO2
+ H2
O 1.152
ClO3
–
+ 3 H+
+ 2 e HClO2
+ H2
O 1.214
ClO3
–
+ 6 H+
+ 5 e 1/2 Cl2
+ 3 H2
O 1.47
ClO3
–
+ 6 H+
+ 6 e Cl–
+ 3 H2
O 1.451
ClO3
–
+ H2
O + 2 e ClO2
–
+ 2 OH–
0.33
ClO3
–
+ 3 H2
O + 6 e Cl–
+ 6 OH–
0.62
ClO4
–
+ 2 H+
+ 2 e ClO3
–
H2
O 1.189
ClO4
–
+ 8 H+
+ 7 e 1/2 Cl2
+ 4 H2
O 1.39
ClO4
–
+ 8 H+
+ 8 e Cl–
+ 4 H2
O 1.389
ClO4
–
+ H2
O + 2 e ClO3
–
+ 2 OH–
0.36
Cm4+
+ e Cm3+
3.0
Cm3+
+ 3 e Cm –2.04
Co2+
+ 2 e Co –0.28
Co3+
+ e Co2+
1.92
Reaction E°/V
[Co(NH3
)6
]3+
+ e [Co(NH3
)6
]2+
0.108
Co(OH)2
+ 2 e Co + 2 OH–
–0.73
Co(OH)3
+ e Co(OH)2
+ OH–
0.17
Cr2+
+ 2 e Cr –0.913
Cr3+
+ e Cr2+
–0.407
Cr3+
+ 3 e Cr –0.744
Cr2
O7
2–
+ 14 H+
+ 6 e 2 Cr3+
+ 7 H2
O 1.36
CrO2
–
+ 2 H2
O + 3 e Cr + 4 OH–
–1.2
HCrO4
–
+ 7 H+
+ 3 e Cr3+
+ 4 H2
O 1.350
CrO2
+ 4 H+
+ e Cr3+
+2H2
O 1.48
Cr(V) + e Cr(IV) 1.34
CrO4
2–
+ 4 H2
O + 3 e Cr(OH)3
+ 5 OH–
–0.13
Cr(OH)3
+ 3 e Cr + 3 OH–
–1.48
Cs+
+ e Cs –3.026
Cu+
+ e Cu 0.521
Cu2+
+ e Cu+
0.153
Cu2+
+ 2 e Cu 0.3419
Cu2+
+ 2 e Cu(Hg) 0.345
Cu3+
+ e Cu2+
2.4
Cu2
O3
+ 6 H+
+ 2e 2Cu2+
+ 3 H2
O 2.0
Cu2+
+ 2 CN–
+ e [Cu(CN)2
]–
1.103
CuI2
–
+ e Cu + 2 I–
0.00
Cu2
O + H2
O + 2 e 2 Cu + 2 OH–
–0.360
Cu(OH)2
+ 2 e Cu + 2 OH–
–0.222
2 Cu(OH)2
+ 2 e Cu2
O + 2 OH–
+ H2
O –0.080
2 D+
+ 2 e D2
–0.013
Dy2+
+ 2 e Dy –2.2
Dy3+
+ 3 e Dy –2.295
Dy3+
+ e Dy2+
–2.6
Er2+
+ 2 e Er –2.0
Er3+
+ 3 e Er –2.331
Er3+
+ e Er2+
–3.0
Es3+
+ e Es2+
–1.3
Es3+
+ 3 e Es –1.91
Es2+
+ 2 e Es –2.23
Eu2+
+ 2 e Eu –2.812
Eu3+
+ 3 e Eu –1.991
Eu3+
+ e Eu2+
–0.36
F2
+ 2 H+
+ 2 e 2 HF 3.053
F2
+ 2 e 2 F–
2.866
F2
O + 2 H+
+ 4 e H2
O + 2 F–
2.153
Fe2+
+ 2 e Fe –0.447
Fe3+
+ 3 e Fe –0.037
Fe3+
+ e Fe2+
0.771
2 HFeO4
–
+ 8 H+
+ 6 e Fe2
O3
+ 5 H2
O 2.09
HFeO4
–
+ 4 H+
+ 3 e FeOOH + 2 H2
O 2.08
HFeO4
–
+ 7 H+
+ 3 e Fe3+
+ 4 H2
O 2.07
Fe2
O3
+ 4 H+
+ 2 e 2 FeOH+
+ H2
O 0.16
[Fe(CN)6
]3–
+ e [Fe(CN)6
]4–
0.358
FeO4
2–
+ 8 H+
+ 3 e Fe3+
+ 4 H2
O 2.20
[Fe(bipy)2
]3+
+ e Fe(bipy)2
]2+
0.78
[Fe(bipy)3
]3+
+ e Fe(bipy)3
]2+
1.03
Fe(OH)3
+ e Fe(OH)2
+ OH–
–0.56
[Fe(phen)3
]3+
+ e [Fe(phen)3
]2+
1.147
[Fe(phen)3
]3+
+ e [Fe(phen)3
]2+
(1 molar
H2
SO4
) 1.06
[Ferricinium]+
+ e ferrocene 0.400
Fm3+
+ e Fm2+
–1.1
Fm3+
+ 3 e Fm –1.89
Fm2+
+ 2 e Fm –2.30
Electrochemical Series 8-21

Reaction E°/V
Fr+
+ e Fr –2.9
Ga3+
+ 3 e Ga –0.549
Ga+
+ e Ga –0.2
GaOH2+
+ H+
+ 3 e Ga + H2
O –0.498
H2
GaO–
3
+ H2
O + 3 e Ga + 4 OH–
–1.219
Gd3+
+ 3 e Gd –2.279
Ge2+
+ 2 e Ge 0.24
Ge4+
+ 4 e Ge 0.124
Ge4+
+ 2 e Ge2+
0.00
GeO2
+ 2 H+
+ 2 e GeO + H2
O –0.118
H2
GeO3
+ 4 H+
+ 4 e Ge + 3 H2
O –0.182
2 H+
+ 2 e H2
0.00000
H2
+ 2 e 2 H–
–2.23
HO2
+ H+
+ e H2
O2
1.495
2 H2
O + 2 e H2
+ 2 OH–
–0.8277
H2
O2
+ 2 H+
+ 2 e 2 H2
O 1.776
Hf4+
+ 4 e Hf –1.55
HfO2+
+ 2 H+
+ 4 e Hf + H2
O –1.724
HfO2
+ 4 H+
+ 4 e Hf + 2 H2
O –1.505
HfO(OH)2
+ H2
O + 4 e Hf + 4 OH–
–2.50
Hg2+
+ 2 e Hg 0.851
2 Hg2+
+ 2 e Hg2
2+
0.920
Hg2
2+
+ 2 e 2 Hg 0.7973
Hg2
(ac)2
+ 2 e 2 Hg + 2(ac)–
0.51163
Hg2
Br2
+ 2 e 2 Hg + 2 Br–
0.13923
Hg2
Cl2
+ 2 e 2 Hg + 2 Cl–
0.26808
Hg2
HPO4
+ 2 e 2 Hg + HPO4
2–
0.6359
Hg2
I2
+ 2 e 2 Hg + 2 I–
–0.0405
Hg2
O + H2
O + 2 e 2 Hg + 2 OH–
0.123
HgO + H2
O + 2 e Hg + 2 OH–
0.0977
Hg(OH)2
+ 2 H+
+ 2 e Hg + 2 H2
O 1.034
Hg2
SO4
+ 2 e 2 Hg + SO4
2–
0.6125
Ho2+
+ 2 e Ho –2.1
Ho3+
+ 3 e Ho –2.33
Ho3+
+ e Ho2+
–2.8
I2
+ 2 e 2 I–
0.5355
I3
–
+ 2 e 3 I–
0.536
H3
IO6
2–
+ 2 e IO–
3
+ 3 OH–
0.7
H5
IO6
+ H+
+ 2 e IO3
–
+ 3 H2
O 1.601
2 HIO + 2 H+
+ 2 e I2
+ 2 H2
O 1.439
HIO + H+
+ 2 e I–
+ H2
O 0.987
IO–
+ H2
O + 2 e I–
+ 2 OH–
0.485
2 IO3
–
+ 12 H+
+ 10 e I2
+ 6 H2
O 1.195
IO3
–
+ 6 H+
+ 6 e I–
+ 3 H2
O 1.085
IO3
–
+ 2 H2
O + 4 e IO–
+ 4 OH–
0.15
IO3
–
+ 3 H2
O + 6 e IO–
+ 6 OH–
0.26
In+
+ e In –0.14
In2+
+ e In+
–0.40
In3+
+ e In2+
–0.49
In3+
+ 2 e In+
–0.443
In3+
+ 3 e In –0.3382
In(OH)3
+ 3 e In + 3 OH–
–0.99
In(OH)4
–
+ 3 e In + 4 OH–
–1.007
In2
O3
+ 3 H2
O + 6 e 2 In + 6 OH–
–1.034
Ir3+
+ 3 e Ir 1.156
[IrCl6
]2–
+ e [IrCl6
]3–
0.8665
[IrCl6
]3–
+ 3 e Ir + 6 Cl–
0.77
Ir2
O3
+ 3 H2
O + 6 e 2 Ir + 6 OH–
0.098
K+
+ e K –2.931
La3+
+ 3 e La –2.379
Reaction E°/V
La(OH)3
+ 3 e La + 3 OH–
–2.90
Li+
+ e Li –3.0401
Lr3+
+ 3 e Lr –1.96
Lu3+
+ 3 e Lu –2.28
Md3+
+ e Md2+
–0.1
Md3+
+ 3 e Md –1.65
Md2+
+ 2 e Md –2.40
Mg+
+ e Mg –2.70
Mg2+
+ 2 e Mg –2.372
Mg(OH)2
+ 2 e Mg + 2 OH–
–2.690
Mn2+
+ 2 e Mn –1.185
Mn3+
+ e Mn2+
1.5415
MnO2
+ 4 H+
+ 2 e Mn2+
+ 2 H2
O 1.224
MnO4
–
+ e MnO4
2–
0.558
MnO4
–
+ 4 H+
+ 3 e MnO2
+ 2 H2
O 1.679
MnO4
–
+ 8 H+
+ 5 e Mn2+
+ 4 H2
O 1.507
MnO4
–
+ 2 H2
O + 3 e MnO2
+ 4 OH–
0.595
MnO4
2–
+ 2 H2
O + 2 e MnO2
+ 4 OH–
0.60
Mn(OH)2
+ 2 e Mn + 2 OH–
–1.56
Mn(OH)3
+ e Mn(OH)2
+ OH–
0.15
Mn2
O3
+ 6 H+
+ e 2 Mn2+
+ 3 H2
O 1.485
Mo3+
+ 3 e Mo –0.200
MoO2
+ 4 H+
+ 4 e Mo + 4 H2
O –0.152
H3
Mo7
O24
3–
+ 45 H+
+ 42 e 7 Mo + 24 H2
O 0.082
MoO3
+ 6 H+
+ 6 e Mo + 3 H2
O 0.075
N2
+ 2 H2
O + 6 H+
+ 6 e 2 NH4
OH 0.092
3 N2
+ 2 H+
+ 2 e 2 HN3
–3.09
N5
+
+ 3 H+
+ 2 e 2 NH4
+
1.275
N2
O + 2 H+
+ 2 e N2
+ H2
O 1.766
H2
N2
O2
+ 2 H+
+ 2 e N2
+ 2 H2
O 2.65
N2
O4
+ 2 e 2 NO2
–
0.867
N2
O4
+ 2 H+
+ 2 e 2 NHO2
1.065
N2
O4
+ 4 H+
+ 4 e 2 NO + 2 H2
O 1.035
2 NH3
OH+
+ H+
+ 2 e N2
H5
+
+ 2 H2
O 1.42
2 NO + 2 H+
+ 2 e N2
O + H2
O 1.591
2 NO + H2
O + 2 e N2
O + 2 OH–
0.76
HNO2
+ H+
+ e NO + H2
O 0.983
2 HNO2
+ 4 H+
+ 4 e H2
N2
O2
+ 2 H2
O 0.86
2 HNO2
+ 4 H+
+ 4 e N2
O + 3 H2
O 1.297
NO2
–
+ H2
O + e NO + 2 OH–
–0.46
2 NO2
–
+ 2 H2
O + 4 e N2
O2
2–
+ 4 OH–
–0.18
2 NO2
–
+ 3 H2
O + 4 e N2
O + 6 OH–
0.15
NO3
–
+ 3 H+
+ 2 e HNO2
+ H2
O 0.934
NO3
–
+ 4 H+
+ 3 e NO + 2 H2
O 0.957
2 NO3
–
+ 4 H+
+ 2 e N2
O4
+ 2 H2
O 0.803
NO3
–
+ H2
O + 2 e NO2
–
+ 2 OH–
0.01
2 NO3
–
+ 2 H2
O + 2 e N2
O4
+ 4 OH–
–0.85
Na+
+ e Na –2.71
Nb3+
+ 3 e Nb –1.099
NbO2
+ 2 H+
+ 2 e NbO + H2
O –0.646
NbO2
+ 4 H+
+ 4 e Nb + 2 H2
O –0.690
NbO + 2 H+
+ 2 e Nb + H2
O –0.733
Nb2
O5
+ 10 H+
+ 10 e 2 Nb + 5 H2
O –0.644
Nd3+
+ 3 e Nd –2.323
Nd2+
+ 2 e Nd –2.1
Nd3+
+ e Nd2+
–2.7
Ni2+
+ 2 e Ni –0.257
Ni(OH)2
+ 2 e Ni + 2 OH–
–0.72
NiO2
+ 4 H+
+ 2 e Ni2+
+ 2 H2
O 1.678
NiO2
+ 2 H2
O + 2 e Ni(OH)2
+ 2 OH–
–0.490
8-22 Electrochemical Series

Reaction E°/V
No3+
+ e No2+
1.4
No3+
+ 3 e No –1.20
No2+
+ 2 e No –2.50
Np3+
+ 3 e Np –1.856
Np4+
+ e Np3+
0.147
NpO2
+ H2
O + H+
+ e Np(OH)3
–0.962
O2
+ 2 H+
+ 2 e H2
O2
0.695
O2
+ 4 H+
+ 4 e 2 H2
O 1.229
O2
+ H2
O + 2 e HO2
–
+ OH–
–0.076
O2
+ 2 H2
O + 2 e H2
O2
+ 2 OH–
–0.146
O2
+ 2 H2
O + 4 e 4 OH–
0.401
O3
+ 2 H+
+ 2 e O2
+ H2
O 2.076
O3
+ H2
O + 2 e O2
+ 2 OH–
1.24
O(g) + 2 H+
+ 2 e H2
O 2.421
OH + e OH–
2.02
HO2
–
+ H2
O + 2 e 3 OH–
0.878
OsO4
+ 8 H+
+ 8 e Os + 4 H2
O 0.838
OsO4
+ 4 H+
+ 4 e OsO2
+ 2 H2
O 1.02
[Os(bipy)2
]3+
+ e [Os(bipy)2
]2+
0.81
[Os(bipy)3
]3+
+ e [Os(bipy)3
]2+
0.80
P(red) + 3 H+
+ 3 e PH3
(g) –0.111
P(white) + 3 H+
+ 3 e PH3
(g) –0.063
P + 3 H2
O + 3 e PH3
(g) + 3 OH–
–0.87
H2
P2
–
+ e P + 2 OH–
–1.82
H3
PO2
+ H+
+ e P + 2 H2
O –0.508
H3
PO3
+ 2 H+
+ 2 e H3
PO2
+ H2
O –0.499
H3
PO3
+ 3 H+
+ 3 e P + 3 H2
O –0.454
HPO3
2–
+ 2 H2
O + 2 e H2
PO2
–
+ 3 OH–
–1.65
HPO3
2–
+ 2 H2
O + 3 e P + 5 OH–
–1.71
H3
PO4
+ 2 H+
+ 2 e H3
PO3
+ H2
O –0.276
PO4
3–
+ 2 H2
O + 2 e HPO3
2–
+ 3 OH–
–1.05
Pa3+
+ 3 e Pa –1.34
Pa4+
+ 4 e Pa –1.49
Pa4+
+ e Pa3+
–1.9
Pb2+
+ 2 e Pb –0.1262
Pb2+
+ 2 e Pb(Hg) –0.1205
PbBr2
+ 2 e Pb + 2 Br–
–0.284
PbCl2
+ 2 e Pb + 2 Cl–
–0.2675
PbF2
+ 2 e Pb + 2 F–
–0.3444
PbHPO4
+ 2 e Pb + HPO4
2–
–0.465
PbI2
+ 2 e Pb + 2 I–
–0.365
PbO + H2
O + 2 e Pb + 2 OH–
–0.580
PbO2
+ 4 H+
+ 2 e Pb2+
+ 2 H2
O 1.455
HPbO2
–
+ H2
O + 2 e Pb + 3 OH–
–0.537
PbO2
+ H2
O + 2 e PbO + 2 OH–
0.247
PbO2
+ SO4
2–
+ 4 H+
+ 2 e PbSO4
+ 2 H2
O 1.6913
PbSO4
+ 2 e Pb + SO4
2–
–0.3588
PbSO4
+ 2 e Pb(Hg) + SO4
2–
–0.3505
Pd2+
+ 2 e Pd 0.951
[PdCl4
]2–
+ 2 e Pd + 4 Cl–
0.591
[PdCl6
]2–
+ 2 e [PdCl4
]2–
+ 2 Cl–
1.288
Pd(OH)2
+ 2 e Pd + 2 OH–
0.07
Pm2+
+ 2 e Pm –2.2
Pm3+
+ 3 e Pm –2.30
Pm3+
+ e Pm2+
–2.6
Po4+
+ 2 e Po2+
0.9
Po4+
+ 4 e Po 0.76
Pr4+
+ e Pr3+
3.2
Pr2+
+ 2 e Pr –2.0
Pr3+
+ 3 e Pr –2.353
Reaction E°/V
Pr3+
+ e Pr2+
–3.1
Pt2+
+ 2 e Pt 1.18
[PtCl4
]2–
+ 2 e Pt + 4 Cl–
0.755
[PtCl6
]2–
+ 2 e [PtCl4
]2–
+ 2 Cl–
0.68
Pt(OH)2
+ 2 e Pt + 2 OH–
0.14
PtO3
+ 2 H+
+ 2 e PtO2
+ H2
O 1.7
PtO3
+ 4 H+
+ 2 e Pt(OH)2
2+
+ H2
O 1.5
PtOH+
+ H+
+ 2 e Pt + H2
O 1.2
PtO2
+ 2 H+
+ 2 e PtO + H2
O 1.01
PtO2
+ 4 H+
+ 4 e Pt + 2 H2
O 1.00
Pu3+
+ 3 e Pu –2.031
Pu4+
+ e Pu3+
1.006
Pu5+
+ e Pu4+
1.099
PuO2
(OH)2
+ 2 H+
+ 2 e Pu(OH)4
1.325
PuO2
(OH)2
+ H+
+ e PuO2
OH + H2
O 1.062
Ra2+
+ 2 e Ra –2.8
Rb+
+ e Rb –2.98
Re3+
+ 3 e Re 0.300
ReO4
–
+ 4 H+
+ 3 e ReO2
+ 2 H2
O 0.510
ReO2
+ 4 H+
+ 4 e Re + 2 H2
O 0.2513
ReO4
–
+ 2 H+
+ e ReO3
+ H2
O 0.768
ReO4
–
+ 4 H2
O + 7 e Re + 8 OH–
–0.584
ReO4
–
+ 8 H+
+ 7 e Re + 4 H2
O 0.368
Rh+
+ e Rh 0.600
Rh3+
+ 3 e Rh 0.758
[RhCl6
]3–
+ 3 e Rh + 6 Cl–
0.431
RhOH2+
+ H+
+ 3 e Rh + H2
O 0.83
Ru2+
+ 2 e Ru 0.455
Ru3+
+ e Ru2+
0.2487
RuO2
+ 4 H+
+ 2 e Ru2+
+ 2 H2
O 1.120
RuO4
–
+ e RuO4
2–
0.59
RuO4
+ e RuO4
–
1.00
RuO4
+ 6 H+
+ 4 e Ru(OH)2
2+
+ 2 H2
O 1.40
RuO4
+ 8 H+
+ 8 e Ru + 4 H2
O 1.038
[Ru(bipy)3
)3+
+ e–
[Ru(bipy)3
]2+
1.24
[Ru(H2
O)6
]3+
+ e–
[Ru(H2
O)6
]2+
0.23
[Ru(NH3
)6
]3+
+ e–
[Ru(NH3
)6
]2+
0.10
[Ru(en)3
]3+
+ e –
[Ru(en)3
]2+
0.210
[Ru(CN)6
]3–
+ e–
[Ru(CN)6
]4–
0.86
S + 2 e S2–
–0.47627
S + 2H+
+ 2 e H2
S(aq) 0.142
S + H2
O + 2 e SH–
+ OH–
–0.478
2 S + 2 e S2
2–
–0.42836
S2
O6
2–
+ 4 H+
+ 2 e 2 H2
SO3
0.564
S2
O8
2–
+ 2 e 2 SO4
2–
2.010
S2
O8
2–
+ 2 H+
+ 2 e 2 HSO4
–
2.123
S4
O6
2–
+ 2 e 2 S2
O3
2–
0.08
2 H2
SO3
+ H+
+ 2 e HS2
O4
–
+ 2 H2
O –0.056
H2
SO3
+ 4 H+
+ 4 e S + 3 H2
O 0.449
2 SO3
2–
+ 2 H2
O + 2 e S2
O4
2–
+ 4 OH–
–1.12
2 SO3
2–
+ 3 H2
O + 4 e S2
O3
2–
+ 6 OH–
–0.571
SO4
2–
+ 4 H+
+ 2 e H2
SO3
+ H2
O 0.172
2 SO4
2–
+ 4 H+
+ 2 e S2
O6
2–
+ H2
O –0.22
SO4
2–
+ H2
O + 2 e SO3
2–
+ 2 OH–
–0.93
Sb + 3 H+
+ 3 e SbH3
–0.510
Sb2
O3
+ 6 H+
+ 6 e 2 Sb + 3 H2
O 0.152
Sb2
O5
(senarmontite) + 4 H+
+ 4 e Sb2
O3
+
2 H2
O
0.671
Sb2
O5
(valentinite) + 4 H+
+ 4 e Sb2
O3
+ 2
H2
O
0.649

Reaction E°/V
Sb2
O5
+ 6 H+
+ 4 e 2 SbO+
+ 3 H2
O 0.581
SbO+
+ 2 H+
+ 3 e Sb + 2 H2
O 0.212
SbO2
–
+ 2 H2
O + 3 e Sb + 4 OH–
–0.66
SbO3
–
+ H2
O + 2 e SbO2
–
+ 2 OH–
–0.59
Sc3+
+ 3 e Sc –2.077
Se + 2 e Se2–
–0.924
Se + 2 H+
+ 2 e H2
Se(aq) –0.399
H2
SeO3
+ 4 H+
+ 4 e Se + 3 H2
O 0.74
Se + 2 H+
+ 2 e H2
Se –0.082
SeO3
2–
+ 3 H2
O + 4 e Se + 6 OH–
–0.366
SeO4
2–
+ 4 H+
+ 2 e H2
SeO3
+ H2
O 1.151
SeO4
2–
+ H2
O + 2 e SeO3
2–
+ 2 OH–
0.05
SiF6
2–
+ 4 e Si + 6 F–
–1.24
SiO + 2 H+
+ 2 e Si + H2
O –0.8
SiO2
(quartz) + 4 H+
+ 4 e Si + 2 H2
O 0.857
SiO3
2–
+ 3 H2
O + 4 e Si + 6 OH–
–1.697
Sm3+
+ e Sm2+
–1.55
Sm3+
+ 3 e Sm –2.304
Sm2+
+ 2 e Sm –2.68
Sn2+
+ 2 e Sn –0.1375
Sn4+
+ 2 e Sn2+
0.151
Sn(OH)3
+
+ 3 H+
+ 2 e Sn2+
+ 3 H2
O 0.142
SnO2
+ 4 H+
+ 2 e–
Sn2+
+ 2 H2
O –0.094
SnO2
+ 4 H+
+ 4 e Sn + 2 H2
O –0.117
SnO2
+ 3 H+
+ 2 e SnOH+
+ H2
O –0.194
SnO2
+ 2 H2
O + 4 e Sn + 4 OH–
–0.945
HSnO2
–
+ H2
O + 2 e Sn + 3 OH–
–0.909
Sn(OH)6
2–
+ 2 e HSnO2
–
+ 3 OH–
+ H2
O –0.93
Sr+
+ e Sr –4.10
Sr2+
+ 2 e Sr –2.899
Sr2+
+ 2 e Sr(Hg) –1.793
Sr(OH)2
+ 2 e Sr + 2 OH–
–2.88
Ta2
O5
+ 10 H+
+ 10 e 2 Ta + 5 H2
O –0.750
Ta3+
+ 3 e Ta –0.6
Tc2+
+ 2 e Tc 0.400
TcO4
–
+ 4 H+
+ 3 e TcO2
+ 2 H2
O 0.782
Tc3+
+ e Tc2+
0.3
TcO4
–
+ 8 H+
+ 7 e Tc + 4 H2
O 0.472
Tb4+
+ e Tb3+
3.1
Tb3+
+ 3 e Tb –2.28
Te + 2 e Te2–
–1.143
Te + 2 H+
+ 2 e H2
Te –0.793
Te4+
+ 4 e Te 0.568
TeO2
+ 4 H+
+ 4 e Te + 2 H2
O 0.593
TeO3
2–
+ 3 H2
O + 4 e Te + 6 OH–
–0.57
TeO4
–
+ 8 H+
+ 7 e Te + 4 H2
O 0.472
H6
TeO6
+ 2 H+
+ 2 e TeO2
+ 4 H2
O 1.02
Th4+
+ 4 e Th –1.899
ThO2
+ 4 H+
+ 4 e Th + 2 H2
O –1.789
Th(OH)4
+ 4 e Th + 4 OH–
–2.48
Ti2+
+ 2 e Ti –1.630
Ti3+
+ e Ti2+
–0.9
TiO2
+ 4 H+
+ 2 e Ti2+
+ 2 H2
O –0.502
Ti3+
+ 3 e Ti –1.37
TiOH3+
+ H+
+ e Ti3+
+ H2
O –0.055
Reaction E°/V
Tl+
+ e Tl –0.336
Tl+
+ e Tl(Hg) –0.3338
Tl3+
+ 2 e Tl+
1.252
Tl3+
+ 3 e Tl 0.741
TlBr + e Tl + Br–
–0.658
TlCl + e Tl + Cl–
–0.5568
TlI + e Tl + I–
–0.752
Tl2
O3
+ 3 H2
O + 4 e 2 Tl+
+ 6 OH–
0.02
TlOH + e Tl + OH–
–0.34
Tl(OH)3
+ 2 e TlOH + 2 OH–
–0.05
Tl2
SO4
+ 2 e Tl + SO4
2–
–0.4360
Tm3+
+ e Tm2+
–2.2
Tm3+
+ 3 e Tm –2.319
Tm2+
+ 2 e Tm –2.4
U3+
+ 3 e U –1.798
U4+
+ e U3+
–0.607
UO2
+
+ 4 H+
+ e U4+
+ 2 H2
O 0.612
UO2
2+
+ e UO+
2
0.062
UO2
2+
+ 4 H+
+ 2 e U4+
+ 2 H2
O 0.327
UO2
2+
+ 4 H+
+ 6 e U + 2 H2
O –1.444
V2+
+ 2 e V –1.175
V3+
+ e V2+
–0.255
VO2+
+ 2 H+
+ e V3+
+ H2
O 0.337
VO2
+
+ 2 H+
+ e VO2+
+ H2
O 0.991
V2
O5
+ 6 H+
+ 2 e 2 VO2+
+ 3 H2
O 0.957
V2
O5
+ 10 H+
+ 10 e 2 V + 5 H2
O –0.242
V(OH)4
+
+ 2 H+
+ e VO2+
+ 3 H2
O 1.00
V(OH)4
+
+ 4 H+
+ 5 e V + 4 H2
O –0.254
[V(phen)3
]3+
+ e [V(phen)3
]2+
0.14
W3+
+ 3 e W 0.1
W2
O5
+ 2 H+
+ 2 e 2 WO2
+ H2
O –0.031
WO2
+ 4 H+
+ 4 e W + 2 H2
O –0.119
WO3
+ 6 H+
+ 6 e W + 3 H2
O –0.090
WO3
+ 2 H+
+ 2 e WO2
+ H2
O 0.036
2 WO3
+ 2 H+
+ 2 e W2
O5
+ H2
O –0.029
H4
XeO6
+ 2 H+
+ 2 e XeO3
+ 3 H2
O 2.42
XeO3
+ 6 H+
+ 6 e Xe + 3 H2
O 2.10
XeF + e Xe + F–
3.4
Y3+
+ 3 e Y –2.372
Yb3+
+ e Yb2+
–1.05
Yb3+
+ 3 e Yb –2.19
Yb2+
+ 2 e Yb –2.76
Zn2+
+ 2 e Zn –0.7618
Zn2+
+ 2 e Zn(Hg) –0.7628
ZnO2
2–
+ 2 H2
O + 2 e Zn + 4 OH–
–1.215
ZnSO4
7 H2
O + 2 e = Zn(Hg) + SO4
2–
+ 7
H2
O (Saturated ZnSO4
)
–0.7993
ZnOH+
+ H+
+ 2 e Zn + H2
O –0.497
Zn(OH)4
2–
+ 2 e Zn + 4 OH–
–1.199
Zn(OH)2
+ 2 e Zn + 2 OH–
–1.249
ZnO + H2
O + 2 e Zn + 2 OH–
–1.260
ZrO2
+ 4 H+
+ 4 e Zr + 2 H2
O –1.553
ZrO(OH)2
+ H2
O + 4 e Zr + 4 OH–
–2.36
Zr4+
+ 4 e Zr –1.45

TABLE 2. Reduction Reactions Having E° Values More Positive than That of the Standard Hydrogen Electrode
Reaction E°/V
2 H+
+ 2 e H2
0.00000
CuI2
–
+ e Cu + 2 I–
0.00
Ge4+
+ 2 e Ge2+
0.00
NO3
–
+ H2
O + 2 e NO2
–
+ 2 OH–
0.01
Tl2
O3
+ 3 H2
O + 4 e 2 Tl+
+ 6 OH–
0.02
SeO4
2–
+ H2
O + 2 e SeO3
2–
+ 2 OH–
0.05
WO3
+ 2 H+
+ 2 e WO2
+ H2
O 0.036
UO2
2+
+ e = UO2
+
0.062
Pd(OH)2
+ 2 e Pd + 2 OH–
0.07
AgBr + e Ag + Br–
0.07133
MoO3
+ 6 H+
+ 6 e Mo + 3 H2
O 0.075
S4
O6
2–
+ 2 e 2 S2
O3
2–
0.08
H3
Mo7
O24
3–
+ 45 H+
+ 42 e 7 Mo + 24 H2
O 0.082
AgSCN + e Ag + SCN–
0.8951
N2
+ 2 H2
O + 6 H+
+ 6 e 2 NH4
OH 0.092
HgO + H2
O + 2 e Hg + 2 OH–
0.0977
Ir2
O3
+ 3 H2
O + 6 e 2 Ir + 6 OH–
0.098
2 NO + 2 e N2
O2
2–
0.10
[Ru(NH3
)6
]3+
+ e [Ru(NH3
)6
]2+
0.10
W3+
+ 3 e W 0.1
[Co(NH3
)6
]3+
+ e [Co(NH3
)6
]2+
0.108
Hg2
O + H2
O + 2 e 2 Hg + 2 OH–
0.123
Ge4+
+ 4 e Ge 0.124
Hg2
Br2
+ 2 e 2 Hg + 2 Br–
0.13923
Pt(OH)2
+ 2 e Pt + 2 OH–
0.14
[V(phen)3
]3+
+ e [V(phen)3
]2+
0.14
S + 2H+
+ 2 e H2
S(aq) 0.142
Sn(OH)3
+
+ 3 H+
+ 2 e Sn2+
+ 3 H2
O 0.142
Np4+
+ e Np3+
0.147
Ag4
[Fe(CN)6
] + 4 e 4 Ag + [Fe(CN)6
]4–
0.1478
IO3
–
+ 2 H2
O + 4 e IO–
+ 4 OH–
0.15
Mn(OH)3
+ e Mn(OH)2
+ OH–
0.15
2 NO2
–
+ 3 H2
O + 4 e N2
O + 6 OH–
0.15
Sn4+
+ 2 e Sn2+
0.151
Sb2
O3
+ 6 H+
+ 6 e 2 Sb + 3 H2
O 0.152
Cu2+
+ e Cu+
0.153
BiOCl + 2 H+
+ 3 e Bi + Cl–
+ H2
O 0.1583
BiCl4
–
+ 3 e Bi + 4 Cl–
0.16
Fe2
O3
+ 4 H+
+ 2 e 2 FeOH+
+ H2
O 0.16
Co(OH)3
+ e Co(OH)2
+ OH–
0.17
SO4
2–
+ 4 H+
+ 2 e H2
SO3
+ H2
O 0.172
Bi3+
+ 2 e Bi+
0.2
[Ru(en)3
]3+
+ e [Ru(en)3
]2+
0.210
SbO+
+ 2 H+
+ 3 e Sb + 2 H2
O 0.212
AgCl + e Ag + Cl–
0.22233
[Ru(H2
O)6
]3+
+ e [Ru(H2
O)6
]2+
0.23
As2
O3
+ 6 H+
+ 6 e 2 As + 3 H2
O 0.234
Calomel electrode, saturated NaCl (SSCE) 0.2360
Ge2+
+ 2 e Ge 0.24
Ru3+
+ e Ru2+
0.24
Calomel electrode, saturated KCl 0.2412
PbO2
+ H2
O + 2 e PbO + 2 OH–
0.247
HAsO2
+ 3 H+
+ 3 e As + 2 H2
O 0.248
Ru3+
+ e Ru2+
0.2487
ReO2
+ 4 H+
+ 4 e Re + 2 H2
O 0.2513
IO3
–
+ 3 H2
O + 6 e I–
+ OH–
0.26
Reaction E°/V
Hg2
Cl2
+ 2 e 2 Hg + 2 Cl–
0.26808
Calomel electrode, 1 molal KCl 0.2800
Calomel electrode, 1 molar KCl (NCE) 0.2801
At2
+ 2 e 2 At–
0.3
Re3+
+ 3 e Re 0.300
Tc3+
+ e Tc2+
0.3
Bi3+
+ 3 e Bi 0.308
BiO+
+ 2 H+
+ 3 e Bi + H2
O 0.320
UO2
2+
+ 4 H+
+ 2 e U4+
+ 2 H2
O 0.327
ClO3
–
+ H2
O + 2 e ClO2
–
+ 2 OH–
0.33
2 HCNO + 2 H+
+ 2 e (CN)2
+ 2 H2
O 0.330
Calomel electrode, 0.1 molar KCl 0.3337
VO2+
+ 2 H+
+ e V3+
+ H2
O 0.337
Cu2+
+ 2 e Cu 0.3419
Ag2
O + H2
O + 2 e 2 Ag + 2 OH–
0.342
Cu2+
+ 2 e Cu(Hg) 0.345
AgIO3
+ e Ag + IO3
–
0.354
[Fe(CN)6
]3–
+ e [Fe(CN)6
]4–
0.358
ClO4
–
+ H2
O + 2 e ClO–
3
+ 2 OH–
0.36
Ag2
SeO3
+ 2 e 2 Ag + SeO3
2–
0.3629
ReO4
–
+ 8 H+
+ 7 e Re + 4 H2
O 0.368
(CN)2
+ 2 H+
+ 2 e 2 HCN 0.373
[Ferricinium]+
+ e ferrocene 0.400
Tc2+
+ 2 e Tc 0.400
O2
+ 2 H2
O + 4 e 4 OH–
0.401
AgOCN + e Ag + OCN–
0.41
[RhCl6
]3–
+ 3 e Rh + 6 Cl–
0.431
Ag2
CrO4
+ 2 e 2 Ag + CrO4
2–
0.4470
H2
SO3
+ 4 H+
+ 4 e S + 3 H2
O 0.449
Ru2+
+ 2 e Ru 0.455
Ag2
MoO4
+ 2 e 2 Ag + MoO4
2–
0.4573
Ag2
C2
O4
+ 2 e 2 Ag + C2
O4
2–
0.4647
Ag2
WO4
+ 2 e 2 Ag + WO4
2–
0.4660
Ag2
CO3
+ 2 e 2 Ag + CO3
2–
0.47
TcO4
–
+ 8 H+
+ 7 e Tc + 4 H2
O 0.472
TeO4
–
+ 8 H+
+ 7 e Te + 4 H2
O 0.472
IO–
+ H2
O + 2 e I–
+ 2 OH–
0.485
NiO2
+ 2 H2
O + 2 e Ni(OH)2
+ 2 OH–
0.490
Bi+
+ e Bi 0.5
ReO4
–
+ 4 H+
+ 3 e ReO2
+ 2 H2
O 0.510
Hg2
(ac)2
+ 2 e 2 Hg + 2(ac)–
0.51163
Cu+
+ e Cu 0.521
I2
+ 2 e 2 I–
0.5355
I3
–
+ 2 e 3 I–
0.536
AgBrO3
+ e Ag + BrO3
–
0.546
MnO4
–
+ e MnO4
–
0.558
H3
AsO4
+ 2 H+
+ 2 e HAsO2
+ 2 H2
O 0.560
S2
O6
2–
+ 4 H+
+ 2 e 2 H2
SO3
0.564
AgNO2
+ e Ag + NO2
–
0.564
Te4+
+ 4 e Te 0.568
Sb2
O5
+ 6 H+
+ 4 e 2 SbO+
+ 3 H2
O 0.581
RuO4
–
+ e RuO4
2–
0.59
[PdCl4
]2–
+ 2 e Pd + 4 Cl–
0.591
TeO2
+ 4 H+
+ 4 e Te + 2 H2
O 0.593
MnO4
–
+ 2 H2
O + 3 e MnO2
+ 4 OH–
0.595
Rh2+
+ 2 e Rh 0.600

Reaction E°/V
Rh+
+ e Rh 0.600
MnO4
2–
+ 2 H2
O + 2 e MnO2
+ 4 OH–
0.60
2 AgO + H2
O + 2 e Ag2
O + 2 OH–
0.607
BrO3
–
+ 3 H2
O + 6 e Br–
+ 6 OH–
0.61
UO2
+
+ 4 H+
+ e U4+
+ 2 H2
O 0.612
Hg2
SO4
+ 2 e 2 Hg + SO4
2–
0.6125
ClO3
–
+ 3 H2
O + 6 e Cl–
+ 6 OH–
0.62
Hg2
HPO4
+ 2 e 2 Hg + HPO4
2–
0.6359
Ag(ac) + e Ag + (ac)–
0.643
Sb2
O5
(valentinite) + 4 H+
+ 4 e Sb2
O3
+ 2 H2
O 0.649
Ag2
SO4
+ 2 e 2 Ag + SO4
2–
0.654
ClO2
–
+ H2
O + 2 e ClO–
+ 2 OH–
0.66
Sb2
O5
(senarmontite) + 4 H+
+ 4 e Sb2
O5
+ 2
H2
O 0.671
[PtCl6
]2–
+ 2 e [PtCl4
]2–
+ 2 Cl–
0.68
O2
+ 2 H+
+ 2 e H2
O2
0.695
p–benzoquinone + 2 H+
+ 2 e hydroquinone 0.6992
H3
IO6
2–
+ 2 e IO3
–
+ 3 OH–
0.7
Ag2
O3
+ H2
O + 2 e 2 AgO + 2 OH–
0.739
Tl3+
+ 3 e Tl 0.741
[PtCl4
]2–
+ 2 e Pt + 4 Cl–
0.755
Rh3+
+ 3 e Rh 0.758
ClO2
–
+ 2 H2
O + 4 e Cl–
+ 4 OH–
0.76
2 NO + H2
O + 2 e N2
O + 2 OH–
0.76
Po4+
+ 4 e Po 0.76
BrO–
+ H2
O + 2 e Br–
+ 2 OH–
0.761
ReO4
–
+ 2 H+
+e ReO3
+ H2
O 0.768
(CNS)2
+ 2 e 2 CNS–
0.77
[IrCl6
]3–
+ 3 e Ir + 6 Cl–
0.77
Fe3+
+ e Fe2+
0.771
AgF + e Ag + F–
0.779
[Fe(bipy)2
]3+
+ e [Fe(bipy)2
]2+
0.78
TcO4
–
+ 4 H+
+ 3 e TcO2
+ 2 H2
O 0.782
Hg2
2+
+ 2 e 2 Hg 0.7973
Ag+
+ e Ag 0.7996
[Os(bipy)3
]3+
+ e [Os(bipy)3
]2+
0.80
2 NO3
–
+ 4 H+
+ 2 e N2
O4
+ 2 H2
O 0.803
[Os(bipy)2
]3+
+ e [Os(bipy)2
]2+
0.81
RhOH2+
+ H + 3 e Rh + H2
O 0.83
OsO4
+ 8 H+
+ 8 e Os + 4 H2
O 0.838
ClO–
+ H2
O + 2 e Cl–
+ 2 OH–
0.841
Hg2+
+ 2 e Hg 0.851
AuBr4
–
+ 3 e Au + 4 Br–
0.854
SiO2
(quartz) + 4 H+
+ 4 e Si + 2 H2
O 0.857
2 HNO2
+ 4 H+
+ 4 e H2
N2
O2
+ H2
O 0.86
[Ru(CN)6
]3–
+ e–
[Ru(CN)6
]4–
0.86
[IrCl6
]2–
+ e [IrCl6
]3–
0.8665
N2
O4
+ 2 e 2 NO2
–
0.867
HO2
–
+ H2
O + 2 e 3 OH–
0.878
Po4+
+ 2 e Po2+
0.9
2 Hg2+
+ 2 e Hg2
2+
0.920
NO3
–
+ 3 H+
+ 2 e HNO2
+ H2
O 0.934
Pd2+
+ 2 e Pd 0.951
ClO2
(aq) + e ClO2
–
0.954
NO3
–
+ 4 H+
+ 3 e NO + 2 H2
O 0.957
V2
O5
+ 6 H+
+ 2 e 2 VO2+
+ 3 H2
O 0.957
AuBr2
–
+ e Au + 2 Br–
0.959
HNO2
+ H+
+ e NO + H2
O 0.983
Reaction E°/V
HIO + H+
+ 2 e I–
+ H2
O 0.987
VO2
+
+ 2 H+
+ e VO2+
+ H2
O 0.991
PtO2
+ 4 H+
+ 4 e Pt + 2 H2
O 1.00
RuO4
+ e RuO4
–
1.00
V(OH)4
+
+ 2 H+
+ e VO2+
+ 3 H2
O 1.00
AuCl4
–
+ 3 e Au + 4 Cl–
1.002
Pu4+
+ e Pu3+
1.006
PtO2
+ 2 H+
+ 2 e PtO + H2
O 1.01
OsO4
+ 4 H + 4 e OsO2
+ 2 H2
O 1.02
H6
TeO6
+ 2 H+
+ 2 e TeO2
+ 4 H2
O 1.02
[Fe(bipy)3
]3+
+ e [Fe(bipy)3
]2+
1.03
Hg(OH)2
+ 2 H+
+ 2 e Hg + 2 H2
O 1.034
N2
O4
+ 4 H+
+ 4 e 2 NO + 2 H2
O 1.035
RuO4
+ 8 H+
+ 8 e Ru + 4H2
O 1.038
[Fe(phen)3
]3+
+ e [Fe(phen)3
]2+
(1 molar H2
SO4
) 1.06
PuO2
(OH)2
+ H+
+ e PuO2
OH + H2
O 1.062
N2
O4
+ 2 H+
+ 2 e 2 HNO2
1.065
Br2
(l) + 2 e 2Br–
1.066
IO3
–
+ 6 H+
+ 6 e I–
+ 3 H2
O 1.085
Br2
(aq) + 2 e 2Br–
1.0873
Pu5+
+ e Pu4+
1.099
Cu2+
+ 2 CN–
+ e [Cu(CN)2
]–
1.103
RuO2
+ 4 H+
+ 2 e Ru2+
+ 2 H2
O 1.120
[Fe(phen)3
]3+
+ e [Fe(phen)3
]2+
1.147
SeO4
2–
+ 4 H+
+ 2 e H2
SeO3
+ H2
O 1.151
ClO3
–
+ 2 H+
+ e ClO2
+ H2
O 1.152
Ir3+
+ 3 e Ir 1.156
Pt2+
+ 2 e Pt 1.18
ClO4
–
+ 2 H+
+ 2 e ClO3
–
+ H2
O 1.189
2 IO3
–
+ 12 H+
+ 10 e I2
+ 6 H2
O 1.195
PtOH+
+ H+
+ 2 e Pt + H2
O 1.2
ClO3
–
+ 3 H+
+ 2 e HClO2
+ H2
O 1.214
MnO2
+ 4 H+
+ 2 e Mn2+
+ 2 H2
O 1.224
O2
+ 4 H+
+ 4 e 2 H2
O 1.229
O3
+ H2
O + 2 e O2
+ 2 OH–
1.24
[Ru(bipy)3
]3+
+ e [Ru(bipy)3
]2+
1.24
Tl3+
+ 2 e Tl+
1.252
N2
H5
+
+ 3 H+
+ 2 e 2 NH4
+
1.275
ClO2
+ H+
+ e HClO2
1.277
[PdCl6
]2–
+ 2 e [PdCl4
]2–
+ 2 Cl–
1.288
2 HNO2
+ 4 H+
+ 4 e N2
O + 3 H2
O 1.297
AuOH2+
+ H+
+ 2 e Au+
+ H2
O 1.32
PuO2
(OH)2
+ 2 H–
+ 2 e Pu(OH)4
1.325
HBrO + H+
+ 2 e Br–
+ H2
O 1.331
Cr(V) + e Cr(IV) 1.34
HCrO4
–
+ 7 H+
+ 3 e Cr3+
+ 4 H2
O 1.350
Cl2
(g) + 2 e 2Cl–
1.35827
Cr2
O7
2–
+ 14 H+
+ 6 e 2 Cr3+
+ 7 H2
O 1.36
ClO4
–
+ 8 H+
+ 8 e Cl–
+ 4 H2
O 1.389
ClO4
–
+ 8 H+
+ 7 e 1/2 Cl2
+ 4 H2
O 1.39
No3+
+ e No2+
1.4
RuO4
+ 6 H+
+ 4 e Ru(OH)2
2+
+ 2 H2
O 1.40
Au3+
+ 2 e Au+
1.401
2 NH3
OH+
+ H+
+ 2 e N2
H5
+
+ 2 H2
O 1.42
BrO3
–
+ 6 H+
+ 6 e Br–
+ 3 H2
O 1.423
2 HIO + 2 H+
+ 2 e I2
+ 2 H2
O 1.439
Au(OH)3
+ 3 H+
+ 3 e Au–
+ 3 H2
O 1.45

Reaction E°/V
3IO3
–
+ 6 H+
+ 6 e Cl–
+ 3 H2
O 1.451
PbO2
+4 H+
+ 2 e Pb2+
+ 2 H2
O 1.455
ClO3
–
+ 6 H+
+ 5 e 1/2 Cl2
+ 3 H2
O 1.47
CrO2
+ 4 H+
+ e Cr3+
+ 2 H2
O 1.48
BrO3
–
+ 6 H+
+ 5 e 1/2 Br2
+ 3 H2
O 1.482
HClO + H+
+ 2 e Cl–
+ H2
O 1.482
Mn2
O3
+ 6 H+
+ e 2 Mn2+
+ 3 H2
O 1.485
HO2
+ H+
+ e H2
O2
1.495
Au3+
+ 3 e Au 1.498
PtO3
+ 4 H+
+ 2 e Pt(OH)2
2+
+ H2
O 1.5
MnO4
–
+ 8 H+
+ 5 e Mn2+
+ 4 H2
O 1.507
Mn3+
+ e Mn2–
1.5415
HClO2
+ 3 H+
+ 4 e Cl–
+ 2 H2
O 1.570
HBrO + H+
+ e 1/2 Br2
(aq) + H2
O 1.574
2 NO + 2 H+
+ 2 e N2
O + H2
O 1.591
Bi2
O4
+ 4 H+
+ 2 e 2 BiO+
+ 2 H2
O 1.593
HBrO + H+
+ e 1/2 Br2
(l) + H2
O 1.596
H5
IO6
+ H+
+ 2 e IO3
–
+ 3 H2
O 1.601
HClO + H+
+ e 1/2 Cl2
+ H2
O 1.611
HClO2
+ 3 H+
+ 3 e 1/2 Cl2
+ 2 H2
O 1.628
HClO2
+ 2 H+
+ 2 e HClO + H2
O 1.645
Bk4+
+ e Bk3+
1.67
NiO2
+ 4 H+
+ 2 e Ni2+
+ 2 H2
O 1.678
MnO4
–
+ 4 H+
+ 3 e MnO2
+ 2 H2
O 1.679
PbO2
+ SO4
2–
+ 4 H+
+ 2 e PbSO4
+ 2 H2
O 1.6913
Au+
+ e Au 1.692
PtO3
+ 2 H+
+ 2 e PtO2
+ H2
O 1.7
CeOH3+
+ H+
+ e Ce3+
+ H2
O 1.715
Ce4+
+ e Ce3+
1.72
N2
O + 2 H+
+ 2 e N2
+ H2
O 1.766
H2
O2
+ 2 H+
+ 2 e 2 H2
O 1.776
Reaction E°/V
Ag3+
+ e Ag2+
1.8
Au2+
+ e–
Au+
1.8
Ag2
O2
+ 4 H+
+ e 2 Ag + 2 H2
O 1.802
Co3+
+ e Co2–
(2 molar H2
SO4
) 1.83
Ag3+
+ 2 e Ag+
1.9
Co3+
+ e Co2+
1.92
Ag2+
+ e Ag+
1.980
Cu2
O3
+ 6 H+
+ 2 e 2 Cu2+
+ 3 H2
O 2.0
S2
O8
2–
+ 2 e 2 SO4
2–
2.010
OH + e OH–
2.02
HFeO4
–
+ 7 H+
+ 3 e Fe3+
+ 4 H2
O 2.07
O3
+ 2 H+
+ 2 e O2
+ H2
O 2.076
HFeO4
–
+ 4 H+
+ 3 e FeOOH + 2 H2
O 2.08
2 HFeO4
–
+ 8 H+
+ 6 e Fe2
O3
+ 5 H2
O 2.09
XeO3
+ 6 H+
+ 6 e Xe + 3 H2
O 2.10
S2
O8
2–
+ 2 H+
+ 2 e 2 HSO4
–
2.123
F2
O + 2 H+
+ 4 e H2
O + 2 F–
2.153
FeO4
2–
+ 8 H+
+ 3 e Fe3+
+ 4 H2
O 2.20
Cu3+
+ e Cu2+
2.4
H4
XeO6
+ 2 H+
+ 2 e XeO3
+ 3 H2
O 2.42
O(g) + 2 H+
+ 2 e H2
O 2.421
Am4+
+ e Am3+
2.60
H2
N2
O2
+ 2 H+
+ 2 e N2
+ 2 H2
O 2.65
F2
+ 2 e 2 F–
2.866
Cm4+
+ e Cm3+
3.0
F2
+ 2 H+
+ 2 e 2 HF 3.053
Tb4+
+ e Tb3+
3.1
Pr4+
+ e Pr3+
3.2
Cf4+
+ e Cf3+
3.3
XeF + e Xe + F–
3.4
TABLE 3. Reduction Reactions Having E° Values More Negative than That of the Standard Hydrogen Electrode
Reaction E°/V
2 H+
+ 2 e H2
0.00000
2 D+
+ 2 e D2
–0.013
AgCN + e Ag + CN–
–0.017
2 WO3
+ 2 H+
+ 2 e W2
O5
+ H2
O –0.029
W2
O5
+ 2 H+
+ 2 e 2 WO2
+ H2
O –0.031
Ag2
S + 2 H+
+ 2 e 2 Ag + H2
S –0.0366
Fe3+
+ 3 e Fe –0.037
Hg2
I2
+ 2 e 2 Hg + 2 I–
–0.0405
Tl(OH)3
+ 2 e TlOH + 2 OH–
–0.05
TiOH3+
+ H+
+ e Ti3+
+ H2
O –0.055
2 H2
SO3
+ H+
+ 2 e HS2
O4
–
+ 2 H2
O –0.056
P(white) + 3 H+
+ 3 e PH3
(g) –0.063
O2
+ H2
O + 2 e HO2
–
+ OH–
–0.076
2 Cu(OH)2
+ 2 e Cu2
O + 2 OH–
+ H2
O –0.080
Se + 2 H+
+ 2 e H2
Se –0.082
WO3
+ 6 H+
+ 6 e W + 3 H2
O –0.090
SnO2
+ 4 H+
+ 2 e Sn2+
+ 2 H2
O –0.094
Md3+
+ e Md2+
–0.1
P(red) + 3 H+
+ 3 e PH3
(g) –0.111
SnO2
+ 4 H+
+ 4 e Sn + 2 H2
O –0.117
GeO2
+ 2 H+
+ 2 e GeO + H2
O –0.118
Reaction E°/V
WO2
+ 4 H+
+ 4 e W + 2 H2
O –0.119
Pb2+
+ 2 e Pb(Hg) –0.1205
Pb2+
+ 2 e Pb –0.1262
CrO4
2–
+ 4 H2
O + 3 e Cr(OH)3
+ 5 OH–
–0.13
Sn2–
+ 2 e Sn –0.1375
In+
+ e In –0.14
O2
+ 2 H2
O + 2 e H2
O2
+ 2 OH–
–0.146
MoO2
+ 4 H+
+ 4 e Mo + 4 H2
O –0.152
AgI + e Ag + I–
–0.15224
2 NO2
–
+ 2 H2
O + 4 e N2
O2
2–
+ 4 OH–
–0.18
H2
GeO3
+ 4 H+
+ 4 e Ge + 3 H2
O –0.182
SnO2
+ 3 H+
+ 2 e SnOH+
+ H2
O –0.194
CO2
+ 2 H+
+ 2 e HCOOH –0.199
Mo3+
+ 3 e Mo –0.200
Ga+
+ e Ga –0.2
2 SO2
2–
+ 4 H+
+ 2 e S2
O6
2–
+ H2
O –0.22
Cu(OH)2
+ 2 e Cu + 2 OH–
–0.222
V2
O5
+ 10 H+
+ 10 e 2 V + 5 H2
O –0.242
CdSO4
+ 2 e Cd + SO4
2–
–0.246
V(OH)4
+
+ 4 H+
+ 5 e V + 4 H2
O –0.254
V3+
+ e V2+
–0.255

Reaction E°/V
Ni2+
+ 2 e Ni –0.257
PbCl2
+ 2 e Pb + 2 Cl–
–0.2675
H3
PO4
+ 2 H+
+ 2 e H3
PO3
+ H2
O –0.276
Co2+
+ 2 e Co –0.28
PbBr2
+ 2 e Pb + 2 Br–
–0.284
Tl+
+ e Tl(Hg) –0.3338
Tl+
+ e Tl –0.336
In3+
+ 3 e In –0.3382
TlOH + e Tl + OH–
–0.34
PbF2
+ 2 e Pb + 2 F–
–0.3444
PbSO4
+ 2 e Pb(Hg) + SO4
2–
–0.3505
Cd2+
+ 2 e Cd(Hg) –0.3521
PbSO4
+ 2 e Pb + SO4
2–
–0.3588
Cu2
O + H2
O + 2 e 2 Cu + 2 OH–
–0.360
Eu3+
+ e Eu2+
–0.36
PbI2
+ 2 e Pb + 2 I–
–0.365
SeO3
2–
+ 3 H2
O + 4 e Se + 6 OH–
–0.366
Se + 2 H+
+ 2 e H2
Se(aq) –0.399
In2+
+ e In+
–0.40
Cd2+
+ 2 e Cd –0.4030
Cr3+
+ e Cr2+
–0.407
2 S + 2 e S2
2–
–0.42836
Tl2
SO4
+ 2 e Tl + SO4
2–
–0.4360
In3+
+ 2 e In+
–0.443
Fe2+
+ 2 e Fe –0.447
H3
PO3
+ 3 H+
+ 3 e P + 3 H2
O –0.454
Bi2
O3
+ 3 H2
O + 6 e 2 Bi + 6 OH–
–0.46
NO2
–
+ H2
O + e NO + 2 OH –0.46
PbHPO4
+ 2 e Pb + HPO4
2–
–0.465
S + 2 e S2–
–0.47627
S + H2
O + 2 e HS–
+ OH–
–0.478
B(OH)3
+ 7 H+
+ 8 e BH4
–
+ 3 H2
O –0.481
In3+
+ e In2+
–0.49
ZnOH+
+ H+
+ 2 e Zn + H2
O –0.497
GaOH2+
+ H+
+ 3 e Ga + H2
O –0.498
H3
PO3
+ 2 H+
+ 2 e H3
PO2
+ H2
O –0.499
TiO2
+ 4 H+
+ 2 e Ti2+
+ 2 H2
O –0.502
H3
PO2
+ H+
+ e P + 2 H2
O –0.508
Sb + 3 H+
+ 3 e SbH3
–0.510
HPbO2
–
+ H2
O + 2 e Pb + 3 OH–
–0.537
Ga3+
+ 3 e Ga –0.549
TlCl + e Tl + Cl–
–0.5568
Fe(OH)3
+ e Fe(OH)2
+ OH–
–0.56
TeO3
2–
+ 3 H2
O + 4 e Te + 6 OH–
–0.57
2 SO3
2–
+ 3 H2
O + 4 e S2
O3
2–
+ 6 OH–
–0.571
PbO + H2
O + 2 e Pb + 2 OH–
–0.580
ReO2
–
+ 4 H2
O + 7 e Re + 8 OH–
–0.584
SbO3
–
+ H2
O + 2 e SbO2
–
+ 2 OH–
–0.59
Ta3+
+ 3 e Ta –0.6
U4+
+ e U3+
–0.607
As + 3 H+
+ 3 e AsH3
–0.608
Nb2
O5
+ 10 H+
+ 10 e 2 Nb + 5 H2
O –0.644
NbO2
+ 2 H+
+ 2 e NbO + H2
O –0.646
Cd(OH)4
2–
+ 2 e Cd + 4 OH–
–0.658
TlBr + e Tl + Br–
–0.658
SbO2
–
+ 2 H2
O + 3 e Sb + 4 OH–
–0.66
AsO2
–
+ 2 H2
O + 3 e As + 4 OH–
–0.68
Reaction E°/V
NbO2
+ 4 H+
+ 4 e Nb + 2 H2
O –0.690
Ag2
S + 2 e 2 Ag + S2–
–0.691
AsO4
3–
+ 2 H2
O + 2 e AsO2
–
+ 4 OH–
–0.71
Ni(OH)2
+ 2 e Ni + 2 OH–
–0.72
Co(OH)2
+ 2 e Co + 2 OH–
–0.73
NbO + 2 H+
+ 2 e Nb + H2
O –0.733
H2
SeO3
+ 4 H+
+ 4 e Se + 3 H2
O –0.74
Cr3+
+ 3 e Cr –0.744
Ta2
O5
+ 10 H+
+ 10 e 2 Ta + 5 H2
O –0.750
TlI + e Tl + I–
–0.752
Zn2+
+ 2 e Zn –0.7618
Zn2+
+ 2 e Zn(Hg) –0.7628
CdO + H2
O + 2 e Cd + 2 OH–
–0.783
Te + 2 H+
+ 2 e H2
Te –0.793
ZnSO4
.
7H2
O + 2 e Zn(Hg) + SO4
2–
+ 7 H2
O –0.7993
(Saturated ZnSO4
)
Bi + 3 H+
+ 3 e BiH3
–0.8
SiO + 2 H+
+ 2 e Si + H2
O –0.8
Cd(OH)2
+ 2 e Cd(Hg) + 2 OH–
–0.809
2 H2
O + 2 e H2
+ 2 OH–
–0.8277
2 NO–
3
+ 2 H2
O + 2 e N2
O4
+ 4 OH–
–0.85
H3
BO3
+ 3 H+
+ 3 e B + 3 H2
O –0.8698
P + 3 H2
O + 3 e PH3
(g) + 3 OH–
–0.87
Ti3+
+ e Ti2+
–0.9
HSnO2
–
+ H2
O + 2 e Sn + 3 OH–
–0.909
Cr2+
+ 2 e Cr –0.913
Se + 2 e Se2–
–0.924
SO4
2–
+ H2
O + 2 e SO3
2–
+ 2 OH–
–0.93
Sn(OH)6
2–
+ 2 e HSnO2
–
+ 3 OH–
+ H2
O –0.93
SnO2
+ 2 H2
O + 4 e Sn + 4 OH–
–0.945
In(OH)3
+ 3 e In + 3 OH–
–0.99
NpO2
+ H2
O + H+
+ e Np(OH)3
–0.962
In(OH)4
–
+ 3 e In + 4 OH–
–1.007
In2
O3
+ 3 H2
O + 6 e 2 In + 6 OH–
–1.034
PO4
3–
+ 2 H2
O + 2 e HPO3
2–
+ 3 OH–
–1.05
Yb3+
+ e Yb2+
–1.05
Nb3+
+ 3 e Nb –1.099
Fm3+
+ e Fm2+
–1.1
2 SO3
2–
+ 2 H2
O + 2 e S2
O4
2–
+ 4 OH–
–1.12
Te + 2 e Te2–
–1.143
V2+
+ 2 e V –1.175
Mn2+
+ 2 e Mn –1.185
Zn(OH)4
2–
+ 2 e Zn + 4 OH–
–1.199
CrO2
+ 2 H2
O + 3 e Cr + 4 OH–
–1.2
No3+
+ 3 e No –1.20
ZnO2
–
+ 2 H2
O + 2 e Zn + 4 OH–
–1.215
H2
GaO3
–
+ H2
O + 3 e Ga + 4 OH–
–1.219
H2
BO3
–
+ 5 H2
O + 8 e BH4
–
+ 8 OH–
–1.24
SiF6
2–
+ 4 e Si + 6 F–
–1.24
Zn(OH)2
+ 2 e Zn + 2 OH–
–1.249
ZnO + H2
O + 2 e Zn + 2 OH–
–1.260
Es3+
+ e Es2+
–1.3
Pa3+
+ 3 e Pa –1.34
Ti3+
+ 3 e Ti –1.37
Ce3+
+ 3 e Ce(Hg) –1.4373
UO2
2+
+ 4 H+
+ 6 e U + 2 H2
O –1.444
Zr4+
+ 4 e Zr –1.45

Reaction E°/V
Cr(OH)3
+ 3 e Cr + 3 OH–
–1.48
Pa4+
+ 4 e Pa –1.49
HfO2
+ 4 H+
+ 4 e Hf + 2 H2
O –1.505
Hf4+
+ 4 e Hf –1.55
Sm3+
+ e Sm2+
–1.55
ZrO2
+ 4 H+
+ 4 e Zr + 2 H2
O –1.553
Mn(OH)2
+ 2 e Mn + 2 OH–
–1.56
Ba2+
+ 2 e Ba(Hg) –1.570
Bk2+
+ 2 e Bk –1.6
Cf3+
+ e Cf2+
–1.6
Ti2+
+ 2 e Ti –1.630
Md3+
+ 3 e Md –1.65
HPO3
2–
+ 2 H2
O + 2 e H2
PO2
–
+ 3 OH–
–1.65
Al3+
+ 3 e Al –1.662
SiO3
2–
+ H2
O + 4 e Si + 6 OH–
–1.697
HPO3
2–
+ 2 H2
O + 3 e P + 5 OH–
–1.71
HfO2+
+ 2 H+
+ 4 e Hf + H2
O –1.724
ThO2
+ 4 H+
+ 4 e Th + 2 H2
O –1.789
H2
BO3
–
+ H2
O + 3 e B + 4 OH–
–1.79
Sr2+
+ 2 e Sr(Hg) –1.793
U3+
+ 3 e U –1.798
H2
PO–
2
+ e P + 2 OH–
–1.82
Be2+
+ 2 e Be –1.847
Np3+
+ 3 e Np –1.856
Fm3+
+ 3 e Fm –1.89
Th4+
+ 4 e Th –1.899
Am2+
+ 2 e Am –1.9
Pa4+
+ e Pa3+
–1.9
Es3+
+ 3 e Es –1.91
Cf3+
+ 3 e Cf –1.94
Lr3+
+ 3 e Lr –1.96
Eu3+
+ 3 e Eu –1.991
Er2+
+ 2 e Er –2.0
Pr2+
+ 2 e Pr –2.0
Pu3+
+ 3 e Pu –2.031
Cm3+
+ 3 e Cm –2.04
Am3+
+ 3 e Am –2.048
AlF6
3–
+ 3 e Al + 6 F–
–2.069
Sc3+
+ 3 e Sc –2.077
Ho2+
+ 2 e Ho –2.1
Nd2+
+ 2 e Nd –2.1
Cf2+
+ 2 e Cf –2.12
Yb3+
+ 3 e Yb –2.19
Ac3+
+ 3 e Ac –2.20
Dy2+
+ 2 e Dy –2.2
Tm3+
+ e Tm2+
–2.2
Pm2+
+ 2 e Pm –2.2
Es2+
+ 2 e Es –2.23
H2
+ 2 e 2 H–
–2.23
Gd3+
+ 3 e Gd –2.279
Tb3+
+ 3 e Tb –2.28
Lu3+
+ 3 e Lu –2.28
Dy3+
+ 3 e Dy –2.295
Reaction E°/V
Am3+
+ e Am2+
–2.3
Fm2+
+ 2 e Fm –2.30
Pm3+
+ 3 e Pm –2.30
Sm3+
+ 3 e Sm –2.304
Al(OH)3
+ 3 e Al + 3 OH–
–2.31
Tm3+
+ 3 e Tm –2.319
Nd3+
+ 3 e Nd –2.323
Al(OH)–
+ 3 e Al + 4 OH–
–2.328
H2
AlO3
–
+ H2
O + 3 e Al + 4 OH–
–2.33
Ho3+
+ 3 e Ho –2.33
Er3+
+ 3 e Er –2.331
Ce3+
+ 3 e Ce –2.336
Pr3+
+ 3 e Pr –2.353
ZrO(OH)2
+ H2
O + 4 e Zr + 4 OH–
–2.36
Mg2+
+ 2 e Mg –2.372
Y3+
+ 3 e Y –2.372
La3+
+ 3 e La –2.379
Tm2+
+ 2 e Tm –2.4
Md2+
+ 2 e Md –2.40
Th(OH)4
+ 4 e Th + 4 OH–
–2.48
HfO(OH)2
+ H2
O + 4 e Hf + 4 OH–
–2.50
No2+
+ 2 e No –2.50
Dy3+
+ e Dy2+
–2.6
Pm3+
+ e Pm2+
–2.6
Be2
O3
2–
+ 3 H2
O + 4 e 2 Be + 6 OH–
–2.63
Sm2+
+ 2 e Sm –2.68
Mg(OH)2
+ 2 e Mg + 2 OH–
–2.690
Nd3+
+ e Nd2+
–2.7
Mg+
+ e Mg –2.70
Na+
+ e Na –2.71
Yb2+
+ 2 e Yb –2.76
Bk3+
+ e Bk2+
–2.8
Ho3+
+ e Ho2+
–2.8
Ra2+
+ 2 e Ra –2.8
Eu2+
+ 2 e Eu –2.812
Ca2+
+ 2 e Ca –2.868
Sr(OH)2
+ 2 e Sr + 2 OH–
–2.88
Sr2+
+ 2 e Sr –2.899
Fr+
+ e Fr –2.9
La(OH)3
+ 3 e La + 3 OH–
–2.90
Ba2+
+ 2 e Ba –2.912
K+
+ e K –2.931
Rb+
+ e Rb –2.98
Ba(OH)2
+ 2 e Ba + 2 OH–
–2.99
Er3+
+ e Er2+
–3.0
Ca(OH)2
+ 2 e Ca + 2 OH–
–3.02
Cs+
+ e Cs –3.026
Li+
+ e Li –3.0401
3 N2
+ 2 H+
+ 2 e 2 HN3
–3.09
Pr3+
+ e Pr2+
–3.1
Ca+
+ e Ca –3.80
Sr+
+ e Sr –4.10

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