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P2: Standard Reduction Potentials by Value

  • Page ID
    2190
  • The following table provides Eo for selected reduction reactions. Values are from the following sources: Bard, A. J.; Parsons, B.; Jordon, J., eds. Standard Potentials in Aqueous Solutions, Dekker: New York, 1985; Milazzo, G.; Caroli, S.; Sharma, V. K. Tables of Standard Electrode Potentials, Wiley: London, 1978; Swift, E. H.; Butler, E. A. Quantitative Measurements and Chemical Equilibria, Freeman: New York, 1972.

    The table is ordered such that the stronger (more reactive) reductants are at the top and the stronger oxidants are at the bottom.

    Standard Cathode (Reduction) Half-Reaction Standard Reduction Potential E° (volts)
    Li+(aq) + e- \(\rightleftharpoons\) Li(s) –3.040
    Ba2+ + 2e\(\rightleftharpoons\) Ba(s) –2.92
    Rb+ + e- \(\rightleftharpoons\) Rb (s) -2.98
    K+(aq) + e- \(\rightleftharpoons\) K(s) -2.93
    Cs+(aq) + e- \(\rightleftharpoons\) Cs(s) -2.92
    Ba2+(aq) + 2e- \(\rightleftharpoons\) Ba(s) -2.91
    Sr2+(aq) + 2e- \(\rightleftharpoons\) Sr(s) -2.89
    Ca2+(aq) + 2e- \(\rightleftharpoons\) Ca(s) –2.84
    Na+(aq) + e- \(\rightleftharpoons\) Na(s) –2.713
    Mg(OH)2(s) + 2e\(\rightleftharpoons\) Mg(s) + 2OH –2.687
    La3+ + 3e\(\rightleftharpoons\) La(s) –2.38
    Mg2+(aq) + 2e- \(\rightleftharpoons\) Mg(s) -2.356
    Ce3+ + 3e\(\rightleftharpoons\) Ce(s) –2.336
    Al(OH)4 + 3e\(\rightleftharpoons\) Al(s) + 4OH –2.310
    AlF63− + 3e\(\rightleftharpoons\) Al(s) + 6F –2.07
    Be2+ + 2e\(\rightleftharpoons\) Be(s) –1.99
    B(OH)4 + 3e\(\rightleftharpoons\) B(s) + 4OH –1.811
    U3+ + 3e\(\rightleftharpoons\) U(s) –1.66
    Al3+(aq) + 3e- \(\rightleftharpoons\) Al(s) –1.676
    SiF62− + 4e\(\rightleftharpoons\) Si(s) + 6F –1.37
    Zn(CN)42− + 2e\(\rightleftharpoons\) Zn(s) + 4CN –1.34

    Zn(OH)42− + 2e\(\rightleftharpoons\) Zn(s) + 4OH

    –1.285
    Mn2+ + 2e\(\rightleftharpoons\) Mn(s) –1.17
    V2+ + 2e\(\rightleftharpoons\) V(s) –1.13
    2SO32− + 2H2O(l) + 2e \(\rightleftharpoons\) S2O42− + 4OH –1.13

    Zn(NH3)42+ + 2e \(\rightleftharpoons\) Zn(s) + 4NH3

    –1.04
    O2 (aq) + e- \(\rightleftharpoons\) O2-(aq) -1.0

    Cd(CN)42− + 2e\(\rightleftharpoons\) Cd(s) + 4CN

    –0.943

    MoO42− + 4H2O(l) + 6e\(\rightleftharpoons\)Mo(s) + 8OH

    –0.913

    SiO2(s) + 4H+ + 4e\(\rightleftharpoons\) Si(s) + 2H2O(l)

    –0.909

    SO42− + H2O(l) + 2e \(\rightleftharpoons\) SO32−+ 2OH

    –0.936
    Cr2+ + 2e \(\rightleftharpoons\) Cr(s) –0.90

    B(OH)3 + 3H+ + 3e \(\rightleftharpoons\) B(s) + 3H2O(l)

    –0.890
    2H2O(l) + 2e- \(\rightleftharpoons\) H2(g) + 2OH-(aq) -0.828
    Zn2+(aq) + 2e- \(\rightleftharpoons\) Zn(s) –0.7618

    Co(OH)2(s) + 2e\(\rightleftharpoons\) Co(s) + 2OH

    –0.746
    Cr3+(aq) + 3e- \(\rightleftharpoons\) Cr(s) –0.424

    Ni(OH)2 + 2e\(\rightleftharpoons\) Ni(s) + 2OH

    –0.72

    Ag2S(s) + 2e\(\rightleftharpoons\) 2Ag(s) + S2−

    –0.71

    Se(s) + 2e\(\rightleftharpoons\) Se2−

    –0.67 in 1 M NaOH

    Cd(NH3)42+ + 2e\(\rightleftharpoons\) Cd(s) + 4NH3

    –0.622

    2SO32− + 3H2O(l) + 4e \(\rightleftharpoons\)S2O32− + 6OH

    –0.576 in 1 M NaOH

    U4+ + e \(\rightleftharpoons\) U3+

    –0.52

    SiO2(s) + 8H+ + 8e \(\rightleftharpoons\) SiH4(g) + 2H2O(l)

    –0.516
    Sb + 3H+ + 3e \(\rightleftharpoons\) SbH3(g) –0.510

    H3PO3+ 2H+ + 2e \(\rightleftharpoons\) H3PO2 + H2O(l)

    -0.50

    Ni(NH3)62+ + 2e \(\rightleftharpoons\) Ni(s) + 6NH3

    –0.49

    2CO2(g) + 2H+ +2e\(\rightleftharpoons\) H2C2O4

    –0.481
    Cr3+ + e\(\rightleftharpoons\) Cr2+ –0.424
    Fe2+(aq) + 2e- \(\rightleftharpoons\) Fe(s) -0.44

    S(s) + 2e\(\rightleftharpoons\) S2−

    –0.407
    Cd2+(aq) + 2e- \(\rightleftharpoons\) Cd(s) –0.4030

    Ag(NH3)2+ + e\(\rightleftharpoons\) Ag(s) + 2NH3

    –0.373

    Ti3+ + e\(\rightleftharpoons\) Ti2+

    –0.37

    PbSO4(s) + 2e\(\rightleftharpoons\) Pb(s) + SO42−

    –0.356
    Co2+(aq) + 2e- \(\rightleftharpoons\) Co(s) –0.277

    2SO42− + 4H+ + 2e \(\rightleftharpoons\) S2O62− + 2H2O(l)

    –0.25

    N2(g) + 5H+ + 4e\(\rightleftharpoons\) N2H5+

    –0.23

    H3PO4 + 2H+ + 2e\(\rightleftharpoons\) H3PO3 + H2O(l)

    -0.28
    Ni2+(aq) + 2e- \(\rightleftharpoons\) Ni(s) –0.257

    V3+ + e \(\rightleftharpoons\) V2+

    –0.255
    As + 3H+ + 3e \(\rightleftharpoons\) AsH3(g) –0.225

    CO2(g) + 2H+ + 2e \(\rightleftharpoons\) HCO2H

    –0.20
    Mo3+ + 3e \(\rightleftharpoons\) Mo(s) –0.2
    Sn2+ + 2e \(\rightleftharpoons\) Sn(s) –0.19 in 1 M HCl

    Ti2+ + 2e\(\rightleftharpoons\) Ti(s)

    –0.163

    MoO2(s) + 4H+ + 4e\(\rightleftharpoons\) Mo(s) + 2H2O(l)

    –0.152
    AgI(s) + e \(\rightleftharpoons\) Ag(s) + I –0.152
    Sn2+(aq) + 2e- \(\rightleftharpoons\) Sn(s) -0.14
    Pb2+(aq) + 2e- \(\rightleftharpoons\) Pb(s) -0.126

    CrO42− + 4H2O(l) + 3e \(\rightleftharpoons\)2Cr(OH)4 + 4OH

    –0.13 in 1 M NaOH

    WO2(s) + 4H+ + 4e\(\rightleftharpoons\) W(s) + 2H2O(l)

    –0.119

    Se(s) + 2H+ + 2e\(\rightleftharpoons\) H2Se(g)

    –0.115

    CO2(g) + 2H+ + 2e\(\rightleftharpoons\) CO(g) + H2O(l)

    –0.106

    WO3(s) + 6H+ + 6e\(\rightleftharpoons\) W(s) + 3H2O(l)

    –0.090

    Hg2I2(s) + 2e\(\rightleftharpoons\) 2Hg(l) + 2I

    –0.0405
    Fe3+(aq) + 3e- \(\rightleftharpoons\) Fe(s) -0.037
    2H+(aq) + 2e- \(\rightleftharpoons\) H2(g) 0.00

    P(s,white) + 3H+ + 3e\(\rightleftharpoons\) PH3(g)

    0.06
    AgBr(s) + e\(\rightleftharpoons\) Ag(s) + Br 0.071

    S4O62− + 2e\(\rightleftharpoons\)2S2O32−

    0.080

    Co(NH3)63+ +e\(\rightleftharpoons\)Co(NH3)62+

    0.1

    Ru(NH3)63+ + e\(\rightleftharpoons\) Ru(s) + Ru(NH3)62+

    0.10

    S(s) + 2H+ + 2e\(\rightleftharpoons\) H2S

    0.144
    Sn4+(aq) + 2e- \(\rightleftharpoons\) Sn2+(aq) 0.154
    Cu2+(aq) + e- \(\rightleftharpoons\) Cu+(aq) 0.159

    UO22+ + e \(\rightleftharpoons\)UO2+

    0.16

    Co(OH)3(s) + e\(\rightleftharpoons\) Co(OH)2(s) + OH

    0.17
    ClO4-(aq) + H2O(l) + 2e- \(\rightleftharpoons\) ClO3-(aq) + 2OH-(aq) 0.17

    SO42− + 4H+ + 2e \(\rightleftharpoons\) H2SO32−+ H2O(l)

    0.172

    BiCl4 + 3e\(\rightleftharpoons\) Bi(s) + 4Cl

    0.199

    SbO+ + 2H+ + 3e\(\rightleftharpoons\) Sb(s) + H2O(l)

    0.212
    AgCl(s) + e- \(\rightleftharpoons\) Ag(s) + Cl-(aq) 0.2223
    HCHO + 2H+ + 2e\(\rightleftharpoons\) CH3OH 0.2323

    HAsO2 + 3H+ + 3e\(\rightleftharpoons\) As(s) + 2H2O(l)

    0.240
    Ru3+ + e\(\rightleftharpoons\) Ru2+ 0.249

    IO3+ 3H2O(l) + 6e\(\rightleftharpoons\) I + 6OH

    0.257

    Hg2Cl2(s) + 2e\(\rightleftharpoons\) 2Hg(l) + 2Cl

    0.2682

    UO2+ + 4H+ + e \(\rightleftharpoons\)U4+ + 2H2O(l)

    0.27
    Bi3+ + 3e\(\rightleftharpoons\) Bi(s) 0.317

    UO22+ + 4H+ + 2e \(\rightleftharpoons\) U4+ + 2H2O(l)

    0.327

    VO2+ + 2H+ +e\(\rightleftharpoons\)V3+ + H2O(l)

    0.337
    Cu2+(aq) + 2e- \(\rightleftharpoons\) Cu(s) 0.3419
    ClO3-(aq) + H2O(l) + 2e- \(\rightleftharpoons\) ClO2-(aq) + 2OH-(aq) 0.35

    Fe(CN)63− + e \(\rightleftharpoons\) Fe(CN)64−

    0.356

    O2(g) + 2H2O(l) + 4e\(\rightleftharpoons\) 4OH

    0.401

    ClO + H2O(l) + e \(\rightleftharpoons\) ½Cl2(g) + 2OH

    0.421 in 1 M NaOH

     Ag2C2O4(s) + 2e\(\rightleftharpoons\) 2Ag(s) + C2O42−

    0.47
    Cu+(aq) + e- \(\rightleftharpoons\) Cu(s) 0.52
    I2(s) + 2e- \(\rightleftharpoons\) 2I-(aq) 0.5355

    I3 + 2e\(\rightleftharpoons\) 3I

    0.536

    Ga3+ + 3e\(\rightleftharpoons\) Ga(s)

    -0.56
    Cu2+ + Cl + e\(\rightleftharpoons\) CuCl(s) 0.559

    S2O62− + 4H+ + 2e\(\rightleftharpoons\) 2H2SO3

    0.569

    H3AsO4 + 2H+ + 2e\(\rightleftharpoons\) HAsO2 + 2H2O(l)

    0.560
    ClO2-(aq) + H2O(l) + 2e- \(\rightleftharpoons\) ClO-(aq) + 2OH-(aq) 0.59
    MnO4 + 2H2O(l) + 3e\(\rightleftharpoons\) MnO2(s) + 4OH 0.60

    Sb2O5(s) + 6H+ + 4e\(\rightleftharpoons\) 2SbO+ + 3H2O(l)

    0.605
    PtCl62− + 2e\(\rightleftharpoons\) PtCl42- + 2Cl 0.68

    RuO2(s) + 4H+ + 4e\(\rightleftharpoons\) Ru(s) + 2H2O(l)

    0.68

    O2(g) + 2H+ + 2e\(\rightleftharpoons\) H2O2

    0.695
    PtCl42− + 2e\(\rightleftharpoons\) Pt(s) + 4Cl 0.73

    H2SeO3 + 4H+ + 4e\(\rightleftharpoons\) Se(s) + 3H2O(l)

    0.74
    Tl3+ + 3e\(\rightleftharpoons\) Tl(s) 0.742
    Fe3+(aq) + e- \(\rightleftharpoons\) Fe2+(aq) 0.771
    Hg22+(aq) + 2e- \(\rightleftharpoons\) 2Hg(l) 0.7960
    Ag+(aq) + e- \(\rightleftharpoons\) Ag(s) 0.7996
    Hg2+(aq) + 2e- \(\rightleftharpoons\) Hg(l) 0.8535
    Cu2+ + I +e\(\rightleftharpoons\) CuI(s) 0.86

    Ru(CN)63− +e\(\rightleftharpoons\) Ru(s) + Ru(CN)64−

    0.86

    ClO + H2O(l) + 2e\(\rightleftharpoons\) Cl + 2OH

    0.890 in 1 M NaOH
    2Hg2+(aq) + 2e- \(\rightleftharpoons\) Hg22+(aq) 0.911

    HgO(s) + 2H+ + 2e\(\rightleftharpoons\) Hg(l) + H2O(l)

    0.926

    NO3 + 3H+ + 2e\(\rightleftharpoons\) HNO2 + H2O(l)

    0.94
    MnO2(s) + 4H+ + e- \(\rightleftharpoons\) Mn3+ (aq) + H2O(I) 0.95
    NO3-(aq) + 4H+(aq) + 3e- \(\rightleftharpoons\) NO(g) + 2H2O(l) 0.96

    HIO + H+ + 2e\(\rightleftharpoons\) I + H2O(l)

    0.985

    HNO2 + H+ +e\(\rightleftharpoons\) NO(g) + H2O(l)

    0.996

    VO22+ + 2H+  +e\(\rightleftharpoons\) VO2+ + H2O(l)

    1.000

    AuCl4 + 3e\(\rightleftharpoons\) Au(s) + 4Cl

    1.002
    NO2 (g) + H+ (aq) + e- \(\rightleftharpoons\) HNO2 (aq)
     
    1.07
    Br2(l) + 2e- \(\rightleftharpoons\) 2Br-(aq) 1.087

    Fe(phen)63+ +e \(\rightleftharpoons\) Fe(phen)62+

    1.147

    SeO43− + 4H+ + e\(\rightleftharpoons\) H2SeO3 + H2O(l)

    1.151

    ClO3 + 2H+ + e\(\rightleftharpoons\) ClO2(g) + H2O

    1.175

    ClO3 + 3H+ + 2e \(\rightleftharpoons\) HClO2 + H2O

    1.181

    IO3 + 6H+ + 5e\(\rightleftharpoons\) ½I2(s) + 3H2O(l)

    1.195
    Pt2+ + 2e\(\rightleftharpoons\) Pt(s) 1.2

    ClO4 + 2H+ + 2e \(\rightleftharpoons\) ClO3 + H2O

    1.201
    O2(g) + 4H+(aq) + 4e- \(\rightleftharpoons\) 2H2O(l) 1.229

    MnO2(s) + 4H+ + 2e\(\rightleftharpoons\) Mn2+ + 2H2O(l)

    1.23

    Tl3+ + 2e \(\rightleftharpoons\) Tl+

    0.77 in 1 M HCl

    2HNO2 + 4H+ + 4e\(\rightleftharpoons\) N2O(g) + 3H2O(l)

    1.297

    HOBr + H+ + 2e\(\rightleftharpoons\) Br + H2O(l)

    1.341
    Cr2O72-(aq) + 14H+(aq) + 6e- \(\rightleftharpoons\) 2Cr3+(aq) + 7H2O(l) 1.36

    Cr2O72− + 14H+ + 6e \(\rightleftharpoons\) 2Cr3+ + 7H2O(l)

    1.36
    Cl2(g) + 2e- \(\rightleftharpoons\) 2Cl-(aq) 1.396

    Au3+ + 2e\(\rightleftharpoons\) Au+

    1.36

    Hg2Br2(s) + 2e\(\rightleftharpoons\) 2Hg(l) + 2Br

    1.392
    Ce4+(aq) + e- \(\rightleftharpoons\) Ce3+(aq) 1.44
    PbO2(s) + 4H+ +2e- \(\rightleftharpoons\) Pb2+(aq) + 2H2O(l) 1.46

    BrO3 + 6H+ + 6e\(\rightleftharpoons\) Br + 3H2O

    1.478

    Mn3+ + e\(\rightleftharpoons\) Mn2+

    1.5
    MnO4-(aq) + 8H+(aq) + 5e- \(\rightleftharpoons\) Mn2+(aq) + 4H2O(l) 1.51

    BrO3 + 6H+ + 5e\(\rightleftharpoons\) ½Br2(l) + 3H2O

    1.5
    Au3+ + 3e\(\rightleftharpoons\) Au(s) 1.52

    2NO(g) + 2H+ + 2e\(\rightleftharpoons\) N2O(g) + H2O(l)

    1.59

    HOBr + H+ + e\(\rightleftharpoons\) ½Br + H2O(l)

    1.604

    HClO2 + 2H+ + 2e\(\rightleftharpoons\) HOCl + H2O

    1.64

    PbO2(s) + 4SO42− + 4H+ + 2e\(\rightleftharpoons\) PbSO4(s) + 2H2O(l)

    1.690

    MnO4 + 4H+ +3e\(\rightleftharpoons\) MnO2(s) + 2H2O(l)

    1.70
    Ce4+ + e\(\rightleftharpoons\) Ce3+ 1.72

    N2O(g) + 2H+ + 2e\(\rightleftharpoons\) N2(g) + H2O(l)

    1.77
    H2O2(aq) + 2H+(aq) + 2e- \(\rightleftharpoons\) 2H2O(l) 1.763
    Au+ + e\(\rightleftharpoons\) Au(s) 1.83
    Co3+(aq) + e- \(\rightleftharpoons\) Co2+(aq) 1.92

    S2O82− + 2e\(\rightleftharpoons\)2SO42−

    1.96
    O3(g) + 2H+(aq) + 2e- \(\rightleftharpoons\) O2(g) + H2O(l) 2.07

    BaO(s) + 2H+ + 2e\(\rightleftharpoons\) Ba(s) + H2O(l)

    2.365
    F2(g) + 2e- \(\rightleftharpoons\) 2F-(aq) 2.87

    F2(g) + 2H+ + 2e\(\rightleftharpoons\) 2HF

    3.053