APPENDIX 9
Standard Half-Cell Electrode Potentials of
Selected Elements
All values are in volts at SATP and have been summarized from Inorganic
Chemistry by D.F. Schriver, P. Atkins, and C.H. Langford, 2nd ed., New York:
Freeman, 1994.
Hydrogen
Acidic solution
Basic solution
⫹1
H⫹
0
0
⫹1
H2
H2O
0
⫺0.828
H2
Group 1: The Alkali Metals
Acidic solution
⫹1
0
Li⫹
⫺3.040
Na⫹
⫺2.714
K⫹
⫺2.936
Rb⫹
⫺2.923
Cs⫹
⫺3.026
Li
Na
K
Rb
Cs
A-25
A-26
APPENDIX 9 / Standard Half-Cell Electrode Potentials of Selected Elements
Group 2: The Alkaline Earth Metals
Acidic solution
Basic solution
⫹2
⫹2
0
⫺1.97
Be2⫹
Be
⫺2.356
Mg2⫹
Mg
⫺2.87
Ca2⫹
Mg
Sr
⫺2.91
Ba2⫹
⫺2.687
Mg(OH)2
Ca
⫺2.90
Sr2⫹
0
Ba
Group 13
Acidic solution
Basic solution
⫹3
⫹3
⫹0
⫺1.676
Al3⫹
⫹3
Al(OH)4⫺
Al
⫹1
1.25
Tl3⫹
Tl⫹
⫹0
⫺2.310
0
⫺0.336
Tl
0.72
Group 14
Acidic solution
⫹4
CO2
⫹2
⫺0.114
⫺0.104
HCOOH
CO
⫺2
0
⫺0.029
0.517
HCHO
0.237
CH3OH
⫺4
0.583
CH4
0.132
C
Basic solution
CO32⫺
⫺0.930
HCO2⫺
⫺1.160
HCHO
C
⫺0.591
⫺1.148
CH3OH
⫺0.245
CH4
Al
A-27
Standard Half-Cell Electrode Potentials of Selected Elements
Acidic solution
Basic solution
⫹4
⫹2
SiO2
⫹4
0
⫺0.909
SiO32⫺
Si
(quartz)
⫺0.088
SnO2
⫺0.104
SnO
(white)
Sn
Sn(OH)62⫺
Pb
PbO2
(black)
Sn4⫹
0.15
Sn2⫹
␣᎑PbO2
1.46
Pb2⫹
1.70
⫹2
0
⫺1.69
(⫺0.93)
Si
(⫺0.91)
SnOOH⫺
Sn
⫺0.137
⫺0.125
0.254
⫺0.578
PbO
Pb
red
⫺0.356
PbSO4
Group 15
Acidic solution
⫹5
⫹4
⫹3
⫹2
⫹1
⫺1
0
0.803
NO3⫺
N2O4
1.07
HNO2
0.996
NO
1.59
N2O
1.77
N2
⫺1.87
NH3OH⫹
1.41
⫺0.05
1.297
0.94
⫺2
⫺3
⫺0.23
1.25
N2H5⫹
1.275
NH4⫹
1.35
Basic solution
⫹5
⫹4
⫹3
⫹2
⫹1
⫺1
0
NO3⫺
⫺0.86
N2O4
0.867
NO2⫺
⫺2
⫺3
⫺1.16
0.25
⫺0.46
NO
0.76
N2O
N2
⫺3.04
NH2OH
0.73
⫺1.05
0.15
0.01
0.94
N2H4
0.1
NH3
0.42
Acidic solution
⫹5
H3PO4
⫹4
⫺0.933
H4P2O6
⫺0.276
⫹3
0.380
H3PO3
⫹1
⫺0.499
H3PO2
⫺0.502
⫺3
0
⫺0.508
P
⫺0.063
PH3
A-28
APPENDIX 9 / Standard Half-Cell Electrode Potentials of Selected Elements
Basic solution
⫹5
⫹3
⫺1.12
PO43⫺
⫹1
⫺1.57
HPO32⫺
H2PO2⫺
⫺3
0
⫺2.05
⫺0.89
P
PH3
⫺1.73
Group 16
Acidic solution
⫺1
0
⫺0.125
O2
HO2
⫺2
1.51
0.695
H2O2
1.763
H2O
1.229
⫹6
HSO4⫺
⫹5
⫺0.253
S2O62⫺
⫹4
0.569
H2SO3
⫹2
0.400
0.158
关S2O82⫺
1.96
S2O32⫺
⫺2
0
0.600
S
0.144
H2S
0.500
SO42⫺兴
Basic solution
⫺1
0
⫺0.33
O2
O2⫺
⫺0.0649
⫺2
0.20
HO2⫺
0.867
OH⫺
0.401
⫹6
SO42⫺
⫹4
⫺0.936
SO32⫺
⫹2
⫺0.576
S2O32⫺
⫺0.659
0
⫺0.742
S
⫺1
⫺0.476
⫺2
HS⫺
A-29
Standard Half-Cell Electrode Potentials of Selected Elements
Group 17: The Halogens
Acidic solution
⫺1
0
3.053
F2
HF
2.979
⫹7
⫹5
⫹4
1.175
CIO4⫺
1.201
CIO2
⫹3
1.188
1.181
CIO3⫺
⫹1
HF2⫺
⫺1
0
1.659
HCIO2
1.674
HCIO
1.630
1.358
Cl2
Cl⫺
1.468
BrO4⫺
1.853
1.447
BrO3⫺
HBrO
1.604
Br2(I )a
Br2(aq)
H5IO6
1.60
1.13
IO3⫺
IO⫺
1.44
1.065
1.087
0.535
I2(s)
I3⫺
Br⫺
I⫺
0.536
Basic solution
⫺1
0
F2
⫹7
⫹5
⫹4
⫺0.481
ClO4⫺
0.374
ClO3⫺
ClO2
⫹3
⫹1
2.866
F⫺
⫺1
0
1.071
0.295
ClO2⫺
0.681
ClO⫺
0.421
Cl2
1.358
Cl⫺
0.890
0.584
BrO4⫺
1.025
BrO3⫺
0.492
BrO⫺
0.455
Br2
0.760
1.065
Br⫺
A-30
APPENDIX 9 / Standard Half-Cell Electrode Potentials of Selected Elements
0.26
0.65
H3lO62⫺
0.15
lO3⫺
lO⫺
0.42
l2
0.535
l⫺
0.48
Group 18: The Noble Gases
Acidic solution
⫹8
⫹6
2.4
H4XeO6(aq)
0
2.12
XeO3(aq)
Xe(g)
2.18
Basic solution
0.99
HXeO83⫺
1.24
HXeO4⫺
Xe(g)
The Transition Metals
Acidic solution
⫹4
Basic solution
⫹3
⫹2
0
⫹4
Ti
TiO2
⫹3
⫹2
0
⫺0.86
TiO2⫹
0.1
Ti3⫹
⫺0.37
⫺1.63
Ti2⫹
⫺1.38
Ti2O3
⫺1.21
Acidic solution
⫹5
VO2⫹
⫹4
1.000
VO2⫹
0.668
⫹3
0.337
V3⫹
⫹2
⫺0.255
V2⫹
0
⫺1.13
V
⫺1.95
TiO
⫺2.13
Ti
Standard Half-Cell Electrode Potentials of Selected Elements
A-31
Basic solution
0.120
VO43⫺
2.19
0.542
HV2O5⫺
V2O3
⫺0.486
VO
⫺0.820
V
1.366
0.749
Acidic solution
⫹6
⫹5
0.55
Cr2O72⫺
⫹4
1.34
Cr(V)
Cr(IV)
⫹3
2.10
⫹2
⫺0.424
Cr3⫹
0
Cr 2⫹
⫺0.90
Cr
⫺0.74
1.38
Basic solution
⫹6
⫹3
⫺0.11
CrO42⫺
⫺0.72
0
⫺1.33
Cr(OH)3(s)
Cr
⫺1.33
Cr(OH)4⫺
Acidic solution
⫹7
MnO4⫺
⫹6
0.90
HMnO4⫺
⫹5
1.28
(H3MnO4)
2.09
1.69
⫹4
2.9
MnO2
⫹3
0.95
Mn3⫹
1.23
⫹2
1.5
Mn2⫹
0
⫺1.18
Mn
A-32
APPENDIX 9 / Standard Half-Cell Electrode Potentials of Selected Elements
Basic solution
⫹7
⫹6
⫹5
⫹4
⫹3
⫹2
0
0.34
MnO4⫺
0.56
MnO42⫺
0.27
0.93
MnO43⫺
MnO2
0.146
Mn2O3
⫺0.088
0.60
0.59
Acidic solution
⫹3
⫹2
0.771
Fe3⫹
0
⫺0.44
Fe2⫹
Fe
⫺0.04
0.361
[Fe(CN6)]3⫺
⫺1.16
[Fe(CN)6]4⫺
Basic solution
⫹6
⫹3
0.81
FeO42⫺
Fe2O3
⫹2
⫺0.86
0
Fe(OH)2
Acidic solution
⫹4
CoO2
⫹3
1.4
Co3⫹
⫹2
1.92
Co2⫹
0
⫺0.282
Co
Neutral solution
⫹3
⫹2
[Co(NH3)6]3⫹
0.058
[Co(NH3)6]2⫹
Basic solution
⫹4
CoO2
⫹3
0.7
Co(OH)3
⫹2
0.42
Co(OH)2
0
⫺0.733
Co
⫺0.89
Fe
⫺0.234
Mn(OH)2
⫺1.56
Mn
Standard Half-Cell Electrode Potentials of Selected Elements
A-33
Acidic solution
⫹4
⫹3
⫹2
1.5
Ni2⫹
NiO2
0
⫺0.257
Ni
Basic solution
NiO2
0.7
NiOOH
0.52
Ni(OH)2
⫺0.72
Ni
Acidic solution
⫹2
⫹1
0.159
Cu2⫹
0
0.520
Cu⫹
Cu
0.340
⫹2
⫹1
0.10
[Cu(NH3)4]2⫹
1.12
Cu2⫹
0
[Cu(NH3)2]⫹
⫺0.10
⫺0.44
[Cu(CN)2]⫺
Cu
Cu
Basic solution
Cu(OH)2
0.14
Cu2O
⫺1.36
Cu
Acidic solution
⫹3
⫹2
⫹1
0
1.756
Ag2O3
1.715
AgO
1.802
Ag⫹
0.799
Ag
Basic solution
Ag2O3
0.887
AgO
0.602
Ag2O
[Ag(NH3)2]⫹
[Ag(CN)2]⫺
0.343
0.373
⫺0.31
Ag
Ag
Ag
A-34
APPENDIX 9 / Standard Half-Cell Electrode Potentials of Selected Elements
Group 12
Acidic solution
⫹2
0
⫺0.762
Zn2⫹
Zn
Basic solution
⫺1.199
[Zn(OH)4]2⫺
Zn
⫺1.246
Zn(OH)2
Zn
Acidic solution
⫹2
⫹1
0
0.854
Hg2⫹
0.9110
0.796
Hg22⫹
Hg
0.268
Hg2Cl2
Basic solution
0.0977
HgO
Hg
The Lanthanons and Actinons
Acidic solution
⫹4
Ce4⫹
⫹3
1.76
⫹2
0
⫺2.34
Ce3⫹
Ce
Acidic solution
⫹6
⫹5
⫹4
⫹3
⫹2
⫺1.66
0.27
UO22⫹
0.17
UO2⫹
0
0.38
U4⫹
⫺0.52
U3⫹
⫺4.7
⫺1.38
U2⫹
⫺0.1
U