electrode potentials

electrode potentials

electrode potentials: see electrochemistry.
The standard electrode potentials are electrode potentials of half cells at equilibrium. They can be used to determine the potential of an electrochemical cell or galvanic cell, or a position of equilibrium for an electrochemical (redox) reaction, or a direction in which an electrochemical reaction can (thermodynamically) proceed.

The values of standard electrode potentials are given in the table below in volts relative to the standard hydrogen electrode and are assembled from references.

The values are for the following conditions:

  • the temperature of 298.15 K (25 °C);
  • the effective concentration of 1 mol/L for each aqueous species or a species in a mercury amalgam;
  • the partial pressure of 101.325 kPa (absolute) (1 atm, 1.01325 bar) for each gaseous reagent. This pressure is used because most literature data are still given for this value rather than for the current standard of 100 kPa.
  • the activity of unity for each pure solid, pure liquid, or for water (solvent).

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Legend: (s) – solid; (l) – liquid; (g) – gas; (aq) – aqueous (default for all charged species); (Hg) – amalgam.

Half-reaction (V) Ref.
& -9
Zz 9
tfrac{3}{2}N2(g) + H+ + e HN3(aq)  
Li+ + e Li(s)  
N2(g) + 4H2O + 2e 2NH2OH(aq) + 2OH  
Cs+ + e Cs(s)  
Rb+ + e Rb(s)  
K+ + e K(s)  
Ba2+ + 2e Ba(s)  
La(OH)3(s) + 3e La(s) + 3OH  
Sr2+ + 2e Sr(s)  
Ca2+ + 2e Ca(s)  
Eu2+ + 2e Eu(s)  
Ra2+ + 2e Ra(s)  
Na+ + e Na(s)  
La3+ + 3e La(s)  
Y3+ + 3e Y(s)  
Mg2+ + 2e Mg(s)  
ZrO(OH)2(s) + H2O + 4e Zr(s) + 4OH  
Al(OH)4 + 3e Al(s) + 4OH  
Al(OH)3(s) + 3e Al(s) + 3OH  
H2(g) + 2e 2H  
Ac3+ + 3e Ac(s)  
Be2+ + 2e Be(s)  
U3+ + 3e U(s)  
Al3+ + 3e Al(s)  
Ti2+ + 2e Ti(s)  
ZrO2(s) + 4H+ + 4e Zr(s) + 2H2O  
Zr4+ + 4e Zr(s)  
TiO(s) + 2H+ + 2e Ti(s) + H2O  
Ti2O3(s) + 2H+ + 2e 2TiO(s) + H2O  
Ti3+ + 3e Ti(s)  
Te(s) + 2e Te2−  
V2+ + 2e V(s)  
Nb3+ + 3e Nb(s)  
Sn(s) + 4H+ + 4e SnH4(g)  
Mn2+ + 2e Mn(s)  
SiO2(s) + 4H+ + 4e Si(s) + 2H2O  
B(OH)3(aq) + 3H+ + 3e B(s) + 3H2O  
TiO2+ + 2H+ + 4e Ti(s) + H2O  
Bi(s) + 3H+ + 3e BiH3  
2H2O + 2e H2(g) + 2OH  
Zn2+ + 2e Zn(Hg)  
Zn2+ + 2e Zn(s)  
Ta2O5(s) + 10H+ + 10e 2Ta(s) + 5H2O  
Cr3+ + 3e Cr(s)  
[Au(CN)2] + e Au(s) + 2CN  
Ta3+ + 3e Ta(s)  
PbO(s) + H2O + 2e Pb(s) + 2OH  
2TiO2(s) + 2H+ + 2e Ti2O3(s) + H2O  
Ga3+ + 3e Ga(s)  
U4+ + e U3+  
H3PO2(aq) + H+ + e P(white) + 2H2O  
H3PO3(aq) + 2H+ + 2e H3PO2(aq) + H2O  
H3PO3(aq) + 3H+ + 3e P(red) + 3H2O  
Fe2+ + 2e Fe(s)  
2CO2(g) + 2H+ + 2e HOOCCOOH(aq)  
Cr3+ + e Cr2+  
Cd2+ + 2e Cd(s)  
GeO2(s) + 2H+ + 2e GeO(s) + H2O  
Cu2O(s) + H2O + 2e 2Cu(s) + 2OH  
PbSO4(s) + 2e Pb(s) + SO42−  
PbSO4(s) + 2e Pb(Hg) + SO42−  
Eu3+ + e Eu2+  
In3+ + 3e In(s)  
Tl+ + e Tl(s)  
Ge(s) + 4H+ + 4e GeH4(g)  
Co2+ + 2e Co(s)  
H3PO4(aq) + 2H+ + 2e H3PO3(aq) + H2O  
V3+ + e V2+  
Ni2+ + 2e Ni(s)  
As(s) + 3H+ + 3e AsH3(g)  
MoO2(s) + 4H+ + 4e Mo(s) + 2H2O  
Si(s) + 4H+ + 4e SiH4(g)  
Sn2+ + 2e Sn(s)  
O2(g) + H+ + e HO2•(aq)  
Pb2+ + 2e Pb(s)  
WO2(s) + 4H+ + 4e W(s) + 2H2O  
P(red) + 3H+ + 3e PH3(g)  
CO2(g) + 2H+ + 2e HCOOH(aq)  
Se(s) + 2H+ + 2e H2Se(g)  
CO2(g) + 2H+ + 2e CO(g) + H2O  
SnO(s) + 2H+ + 2e Sn(s) + H2O  
SnO2(s) + 2H+ + 2e SnO(s) + H2O  
WO3(aq) + 6H+ + 6e W(s) + 3H2O  
P(white) + 3H+ + 3e PH3(g)  
HCOOH(aq) + 2H+ + 2e HCHO(aq) + H2O  
2H+ + 2e H2(g)  ≡ 0
S4O62− + 2e 2S2O32−  +0.08
Fe3O4(s) + 8H+ + 8e 3Fe(s) + 4H2O  +0.085
N2(g) + 2H2O + 6H+ + 6e 2NH4OH(aq)  +0.092
HgO(s) + H2O + 2e Hg(l) + 2OH  +0.0977
Cu(NH3)42+ + e Cu(NH3)2+ + 2NH3  +0.10
Ru(NH3)63+ + e Ru(NH3)62+  +0.10
N2H4(aq) + 4H2O + 2e 2NH4+ + 4OH  +0.11
H2MoO4(aq) + 6H+ + 6e Mo(s) + 4H2O  +0.11
Ge4+ + 4e Ge(s)  +0.12
C(s) + 4H+ + 4e CH4(g)  +0.13
HCHO(aq) + 2H+ + 2e CH3OH(aq)  +0.13
S(s) + 2H+ + 2e H2S(g)  +0.14
Sn4+ + 2e Sn2+  +0.15
Cu2+ + e Cu+  +0.159
HSO4 + 3H+ + 2e SO2(aq) + 2H2O  +0.16
UO22+ + e UO2+  +0.163
SO42− + 4H+ + 2e SO2(aq) + 2H2O  +0.17
TiO2+ + 2H+ + e Ti3+ + H2O  +0.19
Bi3+ + 2e Bi+  +0.2
SbO+ + 2H+ + 3e Sb(s) + H2O  +0.20
H3AsO3(aq) + 3H+ + 3e As(s) + 3H2O  +0.24
GeO(s) + 2H+ + 2e Ge(s) + H2O  +0.26
UO2+ + 4H+ + e U4+ + 2H2O  +0.273
Re3+ + 3e Re(s)  +0.300
Bi3+ + 3e Bi(s)  +0.32
VO2+ + 2H+ + e V3+ + H2O  +0.34
Cu2+ + 2e Cu(s)  +0.340
[Fe(CN)6]3− + e [Fe(CN)6]4−  +0.36
O2(g) + 2H2O + 4e 4OH(aq)  +0.40
H2MoO4 + 6H+ + 3e Mo3+ + 2H2O  +0.43
Bi+ + e Bi(s)  +0.50
CH3OH(aq) + 2H+ + 2e CH4(g) + H2O  +0.50
SO2(aq) + 4H+ + 4e S(s) + 2H2O  +0.50
Cu+ + e Cu(s)  +0.520
CO(g) + 2H+ + 2e C(s) + H2O  +0.52
I2(s) + 2e 2I  +0.54
I3 + 2e 3I  +0.53
[AuI4] + 3e Au(s) + 4I  +0.56
H3AsO4(aq) + 2H+ + 2e H3AsO3(aq) + H2O  +0.56
[AuI2] + e Au(s) + 2I  +0.58
MnO4 + 2H2O + 3e MnO2(s) + 4OH  +0.59
S2O32− + 6H+ + 4e 2S(s) + 3H2O  +0.60
H2MoO4(aq) + 2H+ + 2e MoO2(s) + 2H2O  +0.65
O2(g) + 2H+ + 2e H2O2(aq)  +0.70
Tl3+ + 3e Tl(s)  +0.72
PtCl62− + 2e PtCl42− + 2Cl  +0.726
H2SeO3(aq) + 4H+ + 4e Se(s) + 3H2O  +0.74
PtCl42− + 2e Pt(s) + 4Cl  +0.758
Fe3+ + e Fe2+  +0.77
Ag+ + e Ag(s)  +0.7996
Hg22+ + 2e 2Hg(l)  +0.80
NO3(aq) + 2H+ + e NO2(g) + H2O  +0.80
[AuBr4] + 3e Au(s) + 4Br  +0.85
Hg2+ + 2e Hg(l)  +0.85
MnO4 + H+ + e HMnO4  +0.90
2Hg2+ + 2e Hg22+  +0.91
Pd2+ + 2e Pd(s)  +0.915
[AuCl4] + 3e Au(s) + 4Cl  +0.93
MnO2(s) + 4H+ + e Mn3+ + 2H2O  +0.95
[AuBr2] + e Au(s) + 2Br  +0.96
Br2(l) + 2e 2Br  +1.07
Br2(aq) + 2e 2Br  +1.09
IO3 + 5H+ + 4e HIO(aq) + 2H2O  +1.13
[AuCl2] + e Au(s) + 2Cl  +1.15
HSeO4 + 3H+ + 2e H2SeO3(aq) + H2O  +1.15
Ag2O(s) + 2H+ + 2e 2Ag(s) + H2O  +1.17
ClO3 + 2H+ + e ClO2(g) + H2O  +1.18
Pt2+ + 2e Pt(s)  +1.188
ClO2(g) + H+ + e HClO2(aq)  +1.19
2IO3 + 12H+ + 10e I2(s) + 6H2O  +1.20
ClO4 + 2H+ + 2e ClO3 + H2O  +1.20
O2(g) + 4H+ + 4e 2H2O  +1.23
MnO2(s) + 4H+ + 2e Mn2+ + 2H2O  +1.23
Tl3+ + 2e Tl+  +1.25
Cl2(g) + 2e 2Cl  +1.36
Cr2O7−− + 14H+ + 6e 2Cr3+ + 7H2O  +1.33
CoO2(s) + 4H+ + e Co3+ + 2H2O  +1.42
2NH3OH+ + H+ + 2e N2H5+ + 2H2O  +1.42
2HIO(aq) + 2H+ + 2e I2(s) + 2H2O  +1.44
Ce4+ + e Ce3+  +1.44
BrO3 + 5H+ + 4e HBrO(aq) + 2H2O  +1.45
β-PbO2(s) + 4H+ + 2e Pb2+ + 2H2O  +1.460
α-PbO2(s) + 4H+ + 2e Pb2+ + 2H2O  +1.468
2BrO3 + 12H+ + 10e Br2(l) + 6H2O  +1.48
2ClO3 + 12H+ + 10e Cl2(g) + 6H2O  +1.49
MnO4 + 8H+ + 5e Mn2+ + 4H2O  +1.51
HO2 + H+ + e H2O2(aq)  +1.51
Au3+ + 3e Au(s)  +1.52
NiO2(s) + 4H+ + 2e Ni2+ + 2OH  +1.59
2HClO(aq) + 2H+ + 2e Cl2(g) + 2H2O  +1.63
Ag2O3(s) + 6H+ + 4e 2Ag+ + 3H2O  +1.67
HClO2(aq) + 2H+ + 2e HClO(aq) + H2O  +1.67
Pb4+ + 2e Pb2+  +1.69
MnO4 + 4H+ + 3e MnO2(s) + 2H2O  +1.70
H2O2(aq) + 2H+ + 2e 2H2O  +1.78
AgO(s) + 2H+ + e Ag+ + H2O  +1.77
Co3+ + e Co2+  +1.82
Au+ + e Au(s)  +1.83
BrO4 + 2H+ + 2e BrO3 + H2O  +1.85
Ag2+ + e Ag+  +1.98
S2O82− + 2e 2SO42−  +2.07
O3(g) + 2H+ + 2e O2(g) + H2O  +2.075
HMnO4 + 3H+ + 2e MnO2(s) + 2H2O  +2.09
F2(g) + 2e 2F  +2.87
F2(g) + 2H+ + 2e 2HF(aq)  +3.05

References

  • http://www.jesuitnola.org/upload/clark/Refs/red_pot.htm
  • http://hyperphysics.phy-astr.gsu.edu/Hbase/tables/electpot.html#c1

See also

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