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Appendix L – Standard Electrode (Half-Cell) Potentials

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Half-Reaction E° (V)
Ag++e−⟶AgAg++e−⟶Ag +0.7996
AgCl+e−⟶Ag+Cl−AgCl+e−⟶Ag+Cl− +0.22233
[Ag(CN)2]−+e−⟶Ag+2CN−[Ag(CN)2]−+e−⟶Ag+2CN− −0.31
Ag2CrO4+2e−⟶2Ag+CrO42−Ag2CrO4+2e−⟶2Ag+CrO42− +0.45
[Ag(NH3)2]++e−⟶Ag+2NH3[Ag(NH3)2]++e−⟶Ag+2NH3 +0.373
[Ag(S2O3)2]3++e−⟶Ag+2S2O32−[Ag(S2O3)2]3++e−⟶Ag+2S2O32− +0.017
[AlF6]3−+3e−⟶Al+6F−[AlF6]3−+3e−⟶Al+6F− −2.07
Al3++3e−⟶AlAl3++3e−⟶Al −1.662
Am3++3e−⟶AmAm3++3e−⟶Am −2.048
Au3++3e−⟶AuAu3++3e−⟶Au +1.498
Au++e−⟶AuAu++e−⟶Au +1.692
Ba2++2e−⟶BaBa2++2e−⟶Ba −2.912
Be2++2e−⟶BeBe2++2e−⟶Be −1.847
Br2(aq)+2e−⟶2Br−Br2(aq)+2e−⟶2Br− +1.0873
Ca2++2e−⟶CaCa2++2e−⟶Ca −2.868
Ce3+3e−⟶CeCe3+3e−⟶Ce −2.483
Ce4++e−⟶Ce3+Ce4++e−⟶Ce3+ +1.61
Cd2++2e−⟶CdCd2++2e−⟶Cd −0.4030
[Cd(CN)4]2−+2e−⟶Cd+4CN−[Cd(CN)4]2−+2e−⟶Cd+4CN− −1.09
[Cd(NH3)4]2++2e−⟶Cd+4NH3[Cd(NH3)4]2++2e−⟶Cd+4NH3 −0.61
CdS+2e−⟶Cd+S2−CdS+2e−⟶Cd+S2− −1.17
Cl2+2e−⟶2Cl−Cl2+2e−⟶2Cl− +1.35827
ClO4−+H2O+2e−⟶ClO3−+2OH−ClO4−+H2O+2e−⟶ClO3−+2OH− +0.36
ClO3−+H2O+2e−⟶ClO2−+2OH−ClO3−+H2O+2e−⟶ClO2−+2OH− +0.33
ClO2−+H2O+2e−⟶ClO−+2OH−ClO2−+H2O+2e−⟶ClO−+2OH− +0.66
ClO−+H2O+2e−⟶Cl−+2OH−ClO−+H2O+2e−⟶Cl−+2OH− +0.89
ClO4−+2H3O++2e−⟶ClO3−+3H2OClO4−+2H3O++2e−⟶ClO3−+3H2O +1.189
ClO3−+3H3O++2e−⟶HClO2+4H2OClO3−+3H3O++2e−⟶HClO2+4H2O +1.21
HClO+H3O++2e−⟶Cl−+2H2OHClO+H3O++2e−⟶Cl−+2H2O +1.482
HClO+H3O++e−⟶12Cl2+2H2OHClO+H3O++e−⟶12Cl2+2H2O +1.611
HClO2+2H3O++2e−⟶HClO+3H2OHClO2+2H3O++2e−⟶HClO+3H2O +1.628
Co3++e−⟶Co2+(2mol//H2SO4)Co3++e−⟶Co2+(2mol//H2SO4) +1.83
Co2++2e−⟶CoCo2++2e−⟶Co −0.28
[Co(NH3)6]3++e−⟶[Co(NH3)6]2+[Co(NH3)6]3++e−⟶[Co(NH3)6]2+ +0.1
Co(OH)3+e−⟶Co(OH)2+OH−Co(OH)3+e−⟶Co(OH)2+OH− +0.17
Cr3+3e−⟶CrCr3+3e−⟶Cr −0.744
Cr3++e−⟶Cr2+Cr3++e−⟶Cr2+ −0.407
Cr2++2e−⟶CrCr2++2e−⟶Cr −0.913
[Cu(CN)2]−+e−⟶Cu+2CN−[Cu(CN)2]−+e−⟶Cu+2CN− −0.43
CrO42−+4H2O+3e−⟶Cr(OH)3+5OH−CrO42−+4H2O+3e−⟶Cr(OH)3+5OH− −0.13
Cr2O72−+14H3O++6e−⟶2Cr3++21H2OCr2O72−+14H3O++6e−⟶2Cr3++21H2O +1.232
[Cr(OH)4]−+3e−⟶Cr+4OH−[Cr(OH)4]−+3e−⟶Cr+4OH− −1.2
Cr(OH)3+3e−⟶Cr+3OH−Cr(OH)3+3e−⟶Cr+3OH− −1.48
Cu2++e−⟶Cu+Cu2++e−⟶Cu+ +0.153
Cu2++2e−⟶CuCu2++2e−⟶Cu +0.34
Cu++e−⟶CuCu++e−⟶Cu +0.521
F2+2e−⟶2F−F2+2e−⟶2F− +2.866
Fe2++2e−⟶FeFe2++2e−⟶Fe −0.447
Fe3++e−⟶Fe2+Fe3++e−⟶Fe2+ +0.771
[Fe(CN)6]3−+e−⟶[Fe(CN)6]4−[Fe(CN)6]3−+e−⟶[Fe(CN)6]4− +0.36
Fe(OH)2+2e−⟶Fe+2OH−Fe(OH)2+2e−⟶Fe+2OH− −0.88
FeS+2e−⟶Fe+S2−FeS+2e−⟶Fe+S2− −1.01
Ga3++3e−⟶GaGa3++3e−⟶Ga −0.549
Gd3++3e−⟶GdGd3++3e−⟶Gd −2.279
12H2+e−⟶H−12H2+e−⟶H− −2.23
2H2O+2e−⟶H2+2OH−2H2O+2e−⟶H2+2OH− −0.8277
H2O2+2H3O++2e−⟶4H2OH2O2+2H3O++2e−⟶4H2O +1.776
2H3O++2e−⟶H2+2H2O2H3O++2e−⟶H2+2H2O 0.00
HO2−+H2O+2e−⟶3OH−HO2−+H2O+2e−⟶3OH− +0.878
Hf4++4e−⟶HfHf4++4e−⟶Hf −1.55
Hg2++2e−⟶HgHg2++2e−⟶Hg +0.851
2Hg2++2e−⟶Hg22+2Hg2++2e−⟶Hg22+ +0.92
Hg22++2e−⟶2HgHg22++2e−⟶2Hg +0.7973
[HgBr4]2−+2e−⟶Hg+4Br−[HgBr4]2−+2e−⟶Hg+4Br− +0.21
Hg2Cl2+2e−⟶2Hg+2Cl−Hg2Cl2+2e−⟶2Hg+2Cl− +0.26808
[Hg(CN)4]2−+2e−⟶Hg+4CN−[Hg(CN)4]2−+2e−⟶Hg+4CN− −0.37
[HgI4]2−+2e−⟶Hg+4I−[HgI4]2−+2e−⟶Hg+4I− −0.04
HgS+2e−⟶Hg+S2−HgS+2e−⟶Hg+S2− −0.70
I2+2e−⟶2I−I2+2e−⟶2I− +0.5355
In3++3e−⟶InIn3++3e−⟶In −0.3382
K++e−⟶KK++e−⟶K −2.931
La3++3e−⟶LaLa3++3e−⟶La −2.52
Li++e−⟶LiLi++e−⟶Li −3.04
Lu3++3e−⟶LuLu3++3e−⟶Lu −2.28
Mg2++2e−⟶MgMg2++2e−⟶Mg −2.372
Mn2++2e−⟶MnMn2++2e−⟶Mn −1.185
MnO2+2H2O+2e−⟶Mn(OH)2+2OH−MnO2+2H2O+2e−⟶Mn(OH)2+2OH− −0.05
MnO4−+2H2O+3e−⟶MnO2+4OH−MnO4−+2H2O+3e−⟶MnO2+4OH− +0.558
MnO2+4H++2e−⟶Mn2++2H2OMnO2+4H++2e−⟶Mn2++2H2O +1.23
MnO4−+8H++5e−⟶Mn2++4H2OMnO4−+8H++5e−⟶Mn2++4H2O +1.507
Na++e−⟶NaNa++e−⟶Na −2.71
Nd3++3e−⟶NdNd3++3e−⟶Nd −2.323
Ni2++2e−⟶NiNi2++2e−⟶Ni −0.257
[Ni(NH3)6]2++2e−⟶Ni+6NH3[Ni(NH3)6]2++2e−⟶Ni+6NH3 −0.49
NiO2+4H++2e−⟶Ni2++2H2ONiO2+4H++2e−⟶Ni2++2H2O +1.593
NiO2+2H2O+2e−⟶Ni(OH)2+2OH−NiO2+2H2O+2e−⟶Ni(OH)2+2OH− +0.49
NiS+2e−⟶Ni+S2−NiS+2e−⟶Ni+S2− +0.76
NO3−+4H++3e−⟶NO+2H2ONO3−+4H++3e−⟶NO+2H2O +0.957
NO3−+3H++2e−⟶HNO2+H2ONO3−+3H++2e−⟶HNO2+H2O +0.92
NO3−+H2O+2e−⟶NO2−+2OH−NO3−+H2O+2e−⟶NO2−+2OH− +0.10
Np3++3e−⟶NpNp3++3e−⟶Np −1.856
O2+2H2O+4e−⟶4OH−O2+2H2O+4e−⟶4OH− +0.401
O2+2H++2e−⟶H2O2O2+2H++2e−⟶H2O2 +0.695
O2+4H++4e−⟶2H2OO2+4H++4e−⟶2H2O +1.229
Pb2++2e−⟶PbPb2++2e−⟶Pb −0.1262
PbO2+SO42−+4H++2e−⟶PbSO4+2H2OPbO2+SO42−+4H++2e−⟶PbSO4+2H2O +1.69
PbS+2e−⟶Pb+S2−PbS+2e−⟶Pb+S2− −0.95
PbSO4+2e−⟶Pb+SO42−PbSO4+2e−⟶Pb+SO42− −0.3505
Pd2++2e−⟶PdPd2++2e−⟶Pd +0.987
[PdCl4]2−+2e−⟶Pd+4Cl−[PdCl4]2−+2e−⟶Pd+4Cl− +0.591
Pt2++2e−⟶PtPt2++2e−⟶Pt +1.20
[PtBr4]2−+2e−⟶Pt+4Br−[PtBr4]2−+2e−⟶Pt+4Br− +0.58
[PtCl4]2−+2e−⟶Pt+4Cl−[PtCl4]2−+2e−⟶Pt+4Cl− +0.755
[PtCl6]2−+2e−⟶[PtCl4]2−+2Cl−[PtCl6]2−+2e−⟶[PtCl4]2−+2Cl− +0.68
Pu3+3e−⟶PuPu3+3e−⟶Pu −2.03
Ra2++2e−⟶RaRa2++2e−⟶Ra −2.92
Rb++e−⟶RbRb++e−⟶Rb −2.98
[RhCl6]3−+3e−⟶Rh+6Cl−[RhCl6]3−+3e−⟶Rh+6Cl− +0.44
S+2e−⟶S2−S+2e−⟶S2− −0.47627
S+2H++2e−⟶H2SS+2H++2e−⟶H2S +0.142
Sc3++3e−⟶ScSc3++3e−⟶Sc −2.09
Se+2H++2e−⟶H2SeSe+2H++2e−⟶H2Se −0.399
[SiF6]2−+4e−⟶Si+6F−[SiF6]2−+4e−⟶Si+6F− −1.2
SiO32−+3H2O+4e−⟶Si+6OH−SiO32−+3H2O+4e−⟶Si+6OH− −1.697
SiO2+4H++4e−⟶Si+2H2OSiO2+4H++4e−⟶Si+2H2O −0.86
Sm3++3e−⟶SmSm3++3e−⟶Sm −2.304
Sn4++2e−⟶Sn2+Sn4++2e−⟶Sn2+ +0.151
Sn2++2e−⟶SnSn2++2e−⟶Sn −0.1375
[SnF6]2−+4e−⟶Sn+6F−[SnF6]2−+4e−⟶Sn+6F− −0.25
SnS+2e−⟶Sn+S2−SnS+2e−⟶Sn+S2− −0.94
Sr2++2e−⟶SrSr2++2e−⟶Sr −2.89
TeO2+4H++4e−⟶Te+2H2OTeO2+4H++4e−⟶Te+2H2O +0.593
Th4++4e−⟶ThTh4++4e−⟶Th −1.90
Ti2++2e−⟶TiTi2++2e−⟶Ti −1.630
U3++3e−⟶UU3++3e−⟶U −1.79
V2++2e−⟶VV2++2e−⟶V −1.19
Y3++3e−⟶YY3++3e−⟶Y −2.37
Zn2++2e−⟶ZnZn2++2e−⟶Zn −0.7618
[Zn(CN)4]2−+2e−⟶Zn+4CN−[Zn(CN)4]2−+2e−⟶Zn+4CN− −1.26
[Zn(NH3)4]2++2e−⟶Zn+4NH3[Zn(NH3)4]2++2e−⟶Zn+4NH3 −1.04
Zn(OH)2+2e−⟶Zn+2OH−Zn(OH)2+2e−⟶Zn+2OH− −1.245
[Zn(OH)4]2+2e−⟶Zn+4OH−[Zn(OH)4]2+2e−⟶Zn+4OH− −1.199
ZnS+2e−⟶Zn+S2−ZnS+2e−⟶Zn+S2− −1.40
Zr4+4e−⟶ZrZr4+4e−⟶Zr −1.539

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Appendix L – Standard Electrode (Half-Cell) Potentials Copyright © 2022 by OpenStax is licensed under a Creative Commons Attribution 4.0 International License, except where otherwise noted.

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