Appendix L – Standard Electrode (Half-Cell) Potentials

Appendix L

Standard Electrode (Half-Cell) Potentials

Standard Electrode (Half-Cell) Potentials

Half-Reaction

E° (V)

Ag+ + e ⟶ Ag

+0.7996

AgCl + e ⟶ Ag + Cl−

+0.22233

[Ag(CN)2] + e ⟶ Ag + 2CN−

−0.31

Ag2CrO4 + 2e ⟶ 2Ag + CrO42−

+0.45

[Ag(NH3)2]+ + e ⟶ Ag + 2NH3

+0.373

[Ag(S2O3)2]3+ + e ⟶ Ag + 2S2O32−

+0.017

[AlF6]3− + 3e ⟶ Al + 6F

−2.07

Al3+ + 3e ⟶ Al

−1.662

Am3+ + 3e ⟶ Am

−2.048

Au3+ + 3e ⟶ Au

+1.498

Au+ + e ⟶ Au

+1.692

Ba2+ + 2e ⟶ Ba

−2.912

Be2+ + 2e ⟶ Be

−1.847

Br2(aq) + 2e ⟶ 2Br

+1.0873

Ca2+ + 2e ⟶ Ca

−2.868

Ce3 + 3e ⟶ Ce

−2.483

Ce4+ + e− ⟶ Ce3+

+1.61

Cd2+ + 2e ⟶ Cd

−0.4030

[Cd(NH)4]2− + 2e ⟶ Cd + 4CN

−1.09

[Cd(NH3)4]2+ + 2e ⟶ Cd + 4NH3

−0.61

CdS + 2e ⟶ Cd + S2

−1.17

Cl2 + 2e ⟶ 2Cl

+1.35827

ClO4 − + H2O + 2e− ⟶ ClO3 − + 2OH−

+0.36

ClO3 − + H2O + 2e− ⟶ ClO2 − + 2OH−

+0.33

ClO2 − + H2O + 2e− ⟶ ClO− + 2OH−

+0.66

ClO− + H2O + 2e− ⟶ Cl− + 2OH−

+0.89

ClO4 + 2H3O+ + 2e− ⟶ ClO3 − + 3H2O

+1.189

ClO3 + 3H3O+ + 2e− ⟶ HClO2 + 4H2O

+1.21

HClO + H3O+ + 2e− ⟶ Cl− + 2H2O

+1.482

HClO + H3O+ + e ⟶ [latex]\frac{1}{2}[/latex]Cl2 + 2H2O

+1.611

HClO2 + 2H3 O+ + 2e− ⟶ HClO + 3H2O

+1.628

Co3+ + e− ⟶ Co2+ (2 mol // H2SO4)

+1.83

Co2+ + 2e− ⟶ Co

−0.28

[Co(NH3)6]3+ + e ⟶ [Co(NH3)6]2+

+0.1

Co(OH)3 + e ⟶ Co(OH)2 + OH

+0.17

Cr3 + 3e ⟶ Cr

−0.744

Cr3+ + e ⟶ Cr2+

−0.407

Cr2+ + 2e ⟶ Cr

−0.913

[Cu(CN)2] + e ⟶ Cu + 2CN

−0.43

CrO4 2− + 4H2O + 3e ⟶Cr(OH)3 + 5OH

−0.13

Cr2O7 2− + 14H3O+ + 6e ⟶ 2Cr3+ + 21H2O

+1.232

[Cr(OH)4] + 3e− ⟶ Cr + 4OH

−1.2

Cr(OH)3 + 3e ⟶ Cr + 3OH

−1.48

Cu2+ + e ⟶ Cu+

+0.153

Cu2+ + 2e ⟶ Cu

+0.34

Cu+ + e ⟶ Cu

+0.521

F2 + 2e ⟶ 2F

+2.866

Fe2+ + 2e ⟶ Fe

−0.447

Fe3+ + e ⟶ Fe2+

+0.771

[Fe(CN)6]3- + e ⟶[Fe(CN)6]4-

+0.36

Fe(OH)2 + 2e ⟶ Fe + 2OH

−0.88

FeS + 2e ⟶ Fe + S2−

−1.01

Ga3+ + 3e ⟶ Ga

−0.549

Gd3+ + 3e ⟶ Gd

−2.279

     [latex]\frac{1}{2}[/latex]H2 + e- ⟶ H-

−2.23

2H2O + 2e ⟶ H2 + 2OH

−0.8277

H2O2 + 2H3O+ + 2e ⟶ 4H2O

+1.776

2H3O+ + 2e ⟶ H2 + 2H2O

0.00

HO2 + H2O + 2e ⟶ 3OH

+0.878

Hf4+ + 4e ⟶ Hf

−1.55

Hg2+ + 2e ⟶ Hg

+0.851

2Hg2+ + 2e ⟶ Hg2 2+

+0.92

Hg2 2+ + 2e ⟶ 2Hg

+0.7973

[HgBr4]2− + 2e ⟶ Hg + 4Br

+0.21

Hg2 Cl2 + 2e ⟶ 2Hg + 2Cl−

+0.26808

[Hg(CN)4]2− + 2e ⟶ Hg + 4CN

−0.37

[HgI4]2− + 2e ⟶ Hg + 4I

−0.04

HgS + 2e ⟶ Hg + S2−

−0.70

I2 + 2e ⟶ 2I

+0.5355

In3+ + 3e ⟶ In

−0.3382

K+ + e ⟶ K

−2.931

La3+ + 3e ⟶ La

−2.52

Li+ + e ⟶ Li

−3.04

Lu3+ + 3e ⟶ Lu

−2.28

Mg2+ + 2e ⟶ Mg

−2.372

Mn2+ + 2e ⟶ Mn

−1.185

MnO2 + 2H2O + 2e ⟶ Mn(OH)2 + 2OH

−0.05

MnO4 + 2H2O + 3e ⟶ MnO2 + 4OH

+0.558

MnO2 + 4H+ + 2e ⟶Mn2+ + 2H2O

+1.23

MnO4 + 8H+ + 5e ⟶Mn2+ + 4H2O

+1.507

Na+ + e ⟶ Na

−2.71

Nd3+ + 3e ⟶ Nd

−2.323

Ni2+ + 2e ⟶ Ni

−0.257

[Ni(NH3)6]2+ + 2e ⟶ Ni + 6NH3

−0.49

NiO2 + 4H+ + 2e ⟶Ni2+ + 2H2O

+1.593

NiO2 + 2H2O + 2e ⟶ Ni(OH)2 + 2OH

+0.49

NiS + 2e ⟶ Ni + S2−

+0.76

NO3 + 4H+ + 3e ⟶NO + 2H2O

+0.957

NO3 + 3H+ + 2e ⟶HNO2 + H2O

+0.92

NO3 − + H2O + 2e− ⟶ NO2 + 2OH

+0.10

Np3+ + 3e ⟶ Np

−1.856

O2 + 2H2O + 4e ⟶ 4OH

+0.401

O2 + 2H+ + 2e ⟶H2O2

+0.695

O2 + 4H+ + 4e ⟶ 2H2O

+1.229

Pb2+ + 2e ⟶ Pb

−0.1262

PbO2 + SO4 2− + 4H+ + 2e ⟶PbSO4 + 2H2O

+1.69

PbS + 2e ⟶ Pb + S2−

−0.95

PbSO4 + 2e ⟶ Pb + SO4 2−

−0.3505

Pd2+ + 2e ⟶ Pd

+0.987

[PdCl4]2− + 2e ⟶ Pd + 4Cl

+0.591

Pt2+ + 2e ⟶ Pt

+1.20

[PtBr4]2− + 2e ⟶ Pt + 4Br

+0.58

[PtCl6]2− + 2e ⟶ Pt + 4Cl

+0.755

[PtCl6]2− + 2e ⟶ ⎡PtCl ⎤2− + 2Cl

+0.68

Pu3 + 3e ⟶ Pu

−2.03

Ra2+ + 2e ⟶ Ra

−2.92

Rb+ + e ⟶ Rb

−2.98

[RhCl6]3− + 3e ⟶ Rh + 6Cl

+0.44

S + 2e ⟶ S2−

−0.47627

S + 2H+ + 2e ⟶H2S

+0.142

Sc3+ + 3e ⟶ Sc

−2.09

Se + 2H+ + 2e ⟶H2 Se

−0.399

[SiF6]2− + 4e ⟶ Si + 6F

−1.2

SiO3 2− + 3H2O + 4e ⟶ Si + 6OH

−1.697

SiO2 + 4H+ + 4e ⟶Si + 2H2O

−0.86

Sm3+ + 3e ⟶ Sm

−2.304

Sn4+ + 2e ⟶ Sn2+

+0.151

Sn2+ + 2e ⟶ Sn

−0.1375

[SnF6]2− + 4e ⟶ Sn + 6F

−0.25

SnS + 2e ⟶ Sn + S2

−0.94

Sr2+ + 2e ⟶ Sr

−2.89

TeO2 + 4H+ + 4e ⟶Te + 2H2O

+0.593

Th4+ + 4e ⟶ Th

−1.90

Ti2+ + 2e ⟶ Ti

−1.630

U3+ + 3e ⟶ U

−1.79

V2+ + 2e ⟶ V

−1.19

Y3+ + 3e ⟶ Y

−2.37

Zn2+ + 2e ⟶ Zn

−0.7618

[Zn(CN)4]2− + 2e ⟶ Zn + 4CN

−1.26

[Zn(NH3)4]2+ + 2e ⟶ Zn + 4NH3

−1.04

Zn(OH)2 + 2e ⟶ Zn + 2OH

−1.245

[Zn(OH)4]2 + 2e ⟶ Zn + 4OH

−1.199

ZnS + 2e ⟶ Zn + S2

−1.40

Zr4 + 4e ⟶ Zr

−1.539

Table L1

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