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P1: Standard Reduction Potentials by Element

  • Page ID
    6649
  • The following table provides Eo and Eo´ values 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.

    >Solids, gases, and liquids are identified; all other species are aqueous. Reduction reactions in acidic solution are written using H+ in place of H3O+. You may rewrite a reaction by replacing H+ with H3O+ and adding to the opposite side of the reaction one molecule of H2O per H+; thus

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

    becomes

    H3AsO4 + 2H3O+ + 2e \(\rightleftharpoons\) HAsO2 + 4H2O

    Conditions for formal potentials (Eo´) are listed next to the potential.

    Aluminum E° (V)
    Al3+ + 3e \(\rightleftharpoons\) Al(s) –1.676
    Al(OH)4 + 3e \(\rightleftharpoons\) Al(s) + 4OH –2.310
    AlF63− + 3e \(\rightleftharpoons\) Al(s) + 6F –2.07
    Antimony E° (V)
    Sb + 3H+ + 3e \(\rightleftharpoons\) SbH3(g) –0.510
    Sb2O5(s) + 6H+ + 4e \(\rightleftharpoons\) 2SbO+ + 3H2O(l) 0.605
    SbO+ + 2H+ + 3e \(\rightleftharpoons\) Sb(s) + H2O(l) 0.212
    Arsenic E° (V)
    As + 3H+ + 3e \(\rightleftharpoons\) AsH3(g) –0.225
    H3AsO4 + 2H+ + 2e \(\rightleftharpoons\) HAsO2 + 2H2O(l) 0.560
    HAsO2 + 3H+ + 3e \(\rightleftharpoons\) As(s) + 2H2O(l) 0.240
    Barium E° (V)
    Ba2+ + 2e \(\rightleftharpoons\) Ba(s) –2.91
    BaO(s) + 2H+ + 2e\(\rightleftharpoons\) Ba(s) + H2O(l) 2.365
    Beryllium E° (V)
    Be2+ + 2e \(\rightleftharpoons\) Be(s) –1.99
    Bismuth E° (V)
    Bi3+ + 3e \(\rightleftharpoons\) Bi(s) 0.317
    BiCl4 + 3e \(\rightleftharpoons\) Bi(s) + 4Cl 0.199
    Boron E° (V)
    B(OH)3 + 3H+ + 3e \(\rightleftharpoons\) B(s) + 3H2O(l) –0.890
    B(OH)4 + 3e \(\rightleftharpoons\) B(s) + 4OH –1.811
    Bromine E° (V)
    Br2 + 2e \(\rightleftharpoons\) 2Br 1.087
    HOBr + H+ + 2e \(\rightleftharpoons\) Br + H2O(l) 1.341
    HOBr + H+ + e \(\rightleftharpoons\) ½Br + H2O(l) 1.604
    BrO + H2O(l) +2e \(\rightleftharpoons\) Br + 2OH 0.76 in 1 M NaOH
    BrO3 + 6H+ + 5e \(\rightleftharpoons\) ½Br2(l) + 3H2O 1.5
    BrO3 + 6H+ + 6e \(\rightleftharpoons\)Br + 3H2O 1.478
    Cadmium E° (V)
    Cd2+ + 2e \(\rightleftharpoons\) Cd(s) –0.4030
    Cd(CN)42− + 2e \(\rightleftharpoons\) Cd(s) + 4CN –0.943
    Cd(NH3)42+ + 2e \(\rightleftharpoons\) Cd(s) + 4NH3 –0.622
    Calcium E° (V)
    Ca2+ + 2e \(\rightleftharpoons\) Ca(s) –2.84
    Carbon E° (V)
    CO2(g) + 2H+ + 2e \(\rightleftharpoons\) CO(g) + H2O(l) –0.106
    CO2(g) + 2H+ + 2e \(\rightleftharpoons\) HCO2H –0.20
    2CO2(g) + 2H+ +2e \(\rightleftharpoons\) H2C2O4 –0.481
    HCHO + 2H+ + 2e \(\rightleftharpoons\) CH3OH 0.2323
    Cerium E° (V)
    Ce3+ + 3e \(\rightleftharpoons\) Ce(s) –2.336
    Ce4+ + e \(\rightleftharpoons\) Ce3+ 1.44
    Cesium E° (V)
    \[Cs^+(aq) + e^- \rightleftharpoons Cs (s) \] -2.92
    Chlorine E° (V)
    Cl2(g) + 2e \(\rightleftharpoons\) 2Cl 1.396
    ClO + H2O(l) + e \(\rightleftharpoons\)½Cl2(g) + 2OH 0.421 in 1 M NaOH
    ClO + H2O(l) + 2e \(\rightleftharpoons\) Cl + 2OH 0.890 in 1 M NaOH
    HClO2 + 2H+ + 2e \(\rightleftharpoons\) HOCl + H2O 1.64
    ClO3 + 2H+ + e \(\rightleftharpoons\) ClO2(g) + H2O 1.175
    ClO3 + 3H+ + 2e\(\rightleftharpoons\)HClO2 + H2O 1.181
    ClO4 + 2H+ + 2e\(\rightleftharpoons\) ClO3 + H2O 1.201
    ClO4-(aq) + H2O(l) + 2e- \(\rightleftharpoons\) ClO3-(aq) + 2OH-(aq) 0.17
    ClO3-(aq) + H2O(l) + 2e- \(\rightleftharpoons\) ClO2-(aq) + 2OH-(aq) 0.35
    ClO2-(aq) + H2O(l) + 2e- \(\rightleftharpoons\) ClO-(aq) + 2OH-(aq) 0.59
    Chromium E° (V)
    Cr3+ + e \(\rightleftharpoons\) Cr2+ –0.424
    Cr2+ + 2e \(\rightleftharpoons\) Cr(s) –0.90
    Cr2O72− + 14H+ + 6e\(\rightleftharpoons\) 2Cr3+ + 7H2O(l) 1.36
    CrO42− + 4H2O(l) + 3e\(\rightleftharpoons\)2Cr(OH)4 + 4OH –0.13 in 1 M NaOH
    Cobalt E° (V)
    Co2+ + 2e \(\rightleftharpoons\) Co(s) –0.277
    Co3+ + e \(\rightleftharpoons\) Co2+ 1.92
    Co(NH3)63+ +e \(\rightleftharpoons\) Co(NH3)62+ 0.1
    Co(OH)3(s) + e \(\rightleftharpoons\) Co(OH)2(s) + OH 0.17
    Co(OH)2(s) + 2e \(\rightleftharpoons\) Co(s) + 2OH –0.746
    Copper E° (V)
    Cu+ + e \(\rightleftharpoons\) Cu(s) 0.520
    Cu2+ + e \(\rightleftharpoons\) Cu+ 0.159
    Cu2+ + 2e \(\rightleftharpoons\) Cu(s) 0.3419
    Cu2+ + I +e \(\rightleftharpoons\) CuI(s) 0.86
    Cu2+ + Cl + e \(\rightleftharpoons\) CuCl(s) 0.559
    Fluorine E° (V)
    F2(g) + 2H+ + 2e \(\rightleftharpoons\) 2HF 3.053
    F2(g) + 2e \(\rightleftharpoons\) 2F 2.87
    Gallium E° (V)
    \[Ga^{3+} + 3e^− \rightleftharpoons Ga(s)\] -0.56
    Gold E° (V)
    Au+ + e \(\rightleftharpoons\) Au(s) 1.83
    Au3+ + 2e \(\rightleftharpoons\) Au+ 1.36
    Au3+ + 3e \(\rightleftharpoons\) Au(s) 1.52
    AuCl4 + 3e \(\rightleftharpoons\) Au(s) + 4Cl 1.002
    Hydrogen E° (V)
    \[2H^+ + 2e^− \rightleftharpoons H_2(g) \] 0.00000
    H2O + e \(\rightleftharpoons\) ½H2(g) + OH –0.828
    Iodine E° (V)
    \[I_2(s) + 2e^− \rightleftharpoons 2I^−\] 0.5355
    I3 + 2e \(\rightleftharpoons\) 3I 0.536
    HIO + H+ + 2e \(\rightleftharpoons\) I + H2O(l) 0.985
    IO3 + 6H+ + 5e \(\rightleftharpoons\) ½I2(s) + 3H2O(l) 1.195
    IO3+ 3H2O(l) + 6e \(\rightleftharpoons\) I + 6OH 0.257
    Iron E° (V)
    Fe2+ + 2e \(\rightleftharpoons\) Fe(s) –0.44
    Fe3+ + 3e \(\rightleftharpoons\) Fe(s) –0.037
    Fe3+ + e \(\rightleftharpoons\) Fe2+ 0.771
    Fe(CN)63− + e\(\rightleftharpoons\) Fe(CN)64− 0.356
    Fe(phen)63+ +e\(\rightleftharpoons\)Fe(phen)62+ 1.147
    Lanthanum E° (V)
    La3+ + 3e \(\rightleftharpoons\) La(s) –2.38
    Lead E° (V)
    Pb2+ + 2e \(\rightleftharpoons\) Pb(s) –0.126
    PbO2(s) + 4H+ +2e- \(\rightleftharpoons\) Pb2+(aq) + 2H2O(l) 1.46
    PbO2(s) + 4SO42− + 4H+ + 2e \(\rightleftharpoons\) PbSO4(s) + 2H2O(l) 1.690
    PbSO4(s) + 2e \(\rightleftharpoons\) Pb(s) + SO42− –0.356
    Lithium E° (V)
    Li+ + e \(\rightleftharpoons\) Li(s) –3.040
    Magnesium E° (V)
    Mg2+ + 2e \(\rightleftharpoons\) Mg(s) –2.356
    Mg(OH)2(s) + 2e \(\rightleftharpoons\) Mg(s) + 2OH –2.687
    Manganese E° (V)
    Mn2+ + 2e \(\rightleftharpoons\) Mn(s) –1.17
    Mn3+ + e \(\rightleftharpoons\) Mn2+ 1.5
    MnO2(s) + 4H+ + 2e \(\rightleftharpoons\) Mn2+ + 2H2O(l) 1.23
    MnO2(s) + 4H+ + e- \(\rightleftharpoons\) Mn3+ (aq) + H2O(I) 0.95
    MnO4 + 4H+ +3e \(\rightleftharpoons\) MnO2(s) + 2H2O(l) 1.70
    MnO4+ 8H+ + 5e \(\rightleftharpoons\) Mn2+ + 4H2O(l) 1.51
    MnO4 + 2H2O(l) + 3e \(\rightleftharpoons\) MnO2(s) + 4OH 0.60
    Mercury E° (V)
    Hg2+ + 2e \(\rightleftharpoons\) Hg(l) 0.8535
    2Hg2+ + 2e \(\rightleftharpoons\) Hg22+ 0.911
    Hg22+ + 2e \(\rightleftharpoons\) 2Hg(l) 0.7960
    Hg2Cl2(s) + 2e \(\rightleftharpoons\) 2Hg(l) + 2Cl 0.2682
    HgO(s) + 2H+ + 2e \(\rightleftharpoons\) Hg(l) + H2O(l) 0.926
    Hg2Br2(s) + 2e \(\rightleftharpoons\) 2Hg(l) + 2Br 1.392
    Hg2I2(s) + 2e \(\rightleftharpoons\) 2Hg(l) + 2I –0.0405
    Molybdenum E° (V)
    Mo3+ + 3e \(\rightleftharpoons\) Mo(s) –0.2
    MoO2(s) + 4H+ + 4e \(\rightleftharpoons\) Mo(s) + 2H2O(l) –0.152
    MoO42− + 4H2O(l) + 6e \(\rightleftharpoons\)Mo(s) + 8OH –0.913
    Nickel E° (V)
    Ni2+ + 2e \(\rightleftharpoons\) Ni(s) –0.257
    Ni(OH)2 + 2e \(\rightleftharpoons\) Ni(s) + 2OH –0.72
    Ni(NH3)62+ + 2e \(\rightleftharpoons\) Ni(s) + 6NH3 –0.49
    Nitrogen E° (V)
    \[N_2(g) + 5H^+ + 4e^− \rightleftharpoons N_2H_5^+\] –0.23
    N2O(g) + 2H+ + 2e \(\rightleftharpoons\) N2(g) + H2O(l) 1.77
    2NO(g) + 2H+ + 2e \(\rightleftharpoons\) N2O(g) + H2O(l) 1.59
    HNO2 + H+ +e \(\rightleftharpoons\) NO(g) + H2O(l) 0.996
    2HNO2 + 4H+ + 4e \(\rightleftharpoons\) N2O(g) + 3H2O(l) 1.297
    NO3 + 3H+ + 2e \(\rightleftharpoons\) HNO2 + H2O(l) 0.94
    \[\ce{ NO2(g) + H+ (aq) + e- \rightleftharpoons HNO2(aq) } \] 1.07
    NO3-(aq) + 4H+(aq) + 3e- \(\rightleftharpoons\) NO(g) + 2H2O(l) 0.96
    Oxygen E° (V)
    \[ O_2(g) + 2H^+ + 2e^− \rightleftharpoons H_2O_2\] 0.695
    O2(g) + 4H+ + 4e \(\rightleftharpoons\) 2H2O(l) 1.229
    H2O2 + 2H+ + 2e \(\rightleftharpoons\) 2H2O(l) 1.763
    O2(g) + 2H2O(l) + 4e \(\rightleftharpoons\) 4OH 0.401
    O3(g) + 2H+ + 2e \(\rightleftharpoons\) O2(g) + H2O(l) 2.07
    O2 (g) + e- \(\rightleftharpoons\) O2-(aq) -0.33
    O2 (aq) + e- \(\rightleftharpoons\) O2-(aq) -0.16
    Phosphorous E° (V)
    \[P(s,white) + 3H^+ + 3e^− \rightleftharpoons PH_3(g)\] 0.06
    H3PO3+ 2H+ + 2e \(\rightleftharpoons\) H3PO2 + H2O(l) -0.50
    H3PO4 + 2H+ + 2e \(\rightleftharpoons\) H3PO3 + H2O(l) -0.28
    Platinum E° (V)
    Pt2+ + 2e \(\rightleftharpoons\) Pt(s) 1.2
    PtCl42− + 2e \(\rightleftharpoons\) Pt(s) + 4Cl 0.73
    PtCl62− + 2e \(\rightleftharpoons\) PtCl42- + 2Cl 0.68
    Potassium E° (V)
    K+ + e \(\rightleftharpoons\) K(s) -2.93
    Rubidium E° (V)
    Rb+ + e- \(\rightleftharpoons\) Rb (s) -2.98
    Ruthenium E° (V)
    Ru3+ + e \(\rightleftharpoons\) Ru2+ 0.249
    RuO2(s) + 4H+ + 4e \(\rightleftharpoons\) Ru(s) + 2H2O(l) 0.68
    Ru(NH3)63+ + e \(\rightleftharpoons\) Ru(s) + Ru(NH3)62+ 0.10
    Ru(CN)63− +e \(\rightleftharpoons\) Ru(s) + Ru(CN)64− 0.86
    Selenium E° (V)
    \[Se(s) + 2e^−\rightleftharpoons Se^{2−}\] –0.67 in 1 M NaOH
    Se(s) + 2H+ + 2e \(\rightleftharpoons\) H2Se(g) –0.115
    H2SeO3 + 4H+ + 4e \(\rightleftharpoons\) Se(s) + 3H2O(l) 0.74
    SeO43− + 4H+ + e \(\rightleftharpoons\) H2SeO3 + H2O(l) 1.151
    Silicon E° (V)
    \[SiF_6^{2−} + 4e^− \rightleftharpoons Si(s) + 6F^−\] –1.37
    SiO2(s) + 4H+ + 4e \(\rightleftharpoons\) Si(s) + 2H2O(l) –0.909
    SiO2(s) + 8H+ + 8e \(\rightleftharpoons\) SiH4(g) + 2H2O(l) –0.516
    Silver E° (V)
    Ag+ + e \(\rightleftharpoons\) Ag(s) 0.7996
    AgBr(s) + e \(\rightleftharpoons\) Ag(s) + Br 0.071
    Ag2C2O4(s) + 2e \(\rightleftharpoons\) 2Ag(s) + C2O42− 0.47
    AgCl(s) + e \(\rightleftharpoons\) Ag(s) + Cl 0.2223
    AgI(s) + e \(\rightleftharpoons\) Ag(s) + I –0.152
    Ag2S(s) + 2e \(\rightleftharpoons\) 2Ag(s) + S2− –0.71
    Ag(NH3)2+ + e \(\rightleftharpoons\) Ag(s) + 2NH3 –0.373
    Sodium E° (V)
    \[Na^+ + e^− \rightleftharpoons Na(s)\] –2.713
    Strontium E° (V)
    \[Sr^{2+} + 2e^− \rightleftharpoons Sr(s)\] –2.89
    Sulfur E° (V)
    \[S(s) + 2e^− \rightleftharpoons S^{2−}\] –0.407
    S(s) + 2H+ + 2e \(\rightleftharpoons\) H2S 0.144
    S2O62− + 4H+ + 2e \(\rightleftharpoons\) 2H2SO3 0.569
    S2O82− + 2e \(\rightleftharpoons\)2SO42− 1.96
    S4O62− + 2e \(\rightleftharpoons\)2S2O32− 0.080
    2SO32− + 2H2O(l) + 2e\(\rightleftharpoons\) S2O42− + 4OH –1.13
    2SO32− + 3H2O(l) + 4e\(\rightleftharpoons\)S2O32− + 6OH  
    2SO42− + 4H+ + 2e\(\rightleftharpoons\) S2O62− + 2H2O(l) –0.25
    SO42− + H2O(l) + 2e\(\rightleftharpoons\) SO32−+ 2OH –0.936
    SO42− + 4H+ + 2e\(\rightleftharpoons\) H2SO32−+ H2O(l) 0.172
    Thallium E° (V)
    \[Tl^{3+} + 2e^− \rightleftharpoons Tl^+\] 0.77 in 1 M HCl
    Tl3+ + 3e \(\rightleftharpoons\) Tl(s) 0.742
    Tin E° (V)
    Sn2+ + 2e\(\rightleftharpoons\) Sn(s) -0.14
    Sn4+ + 2e \(\rightleftharpoons\) Sn2+ 0.154
    Titanium E° (V)
    \[Ti^{2+} + 2e^− \rightleftharpoons Ti(s)\] –0.163
    Ti3+ + e \(\rightleftharpoons\) Ti2+ –0.37
    Tungsten E° (V)
    \[WO_2(s) + 4H^+ + 4e^− \rightleftharpoons W(s) + 2H_2O(l)\] –0.119
    WO3(s) + 6H+ + 6e \(\rightleftharpoons\) W(s) + 3H2O(l) –0.090
    Uranium E° (V)
    U3+ + 3e \(\rightleftharpoons\) U(s) –1.66
    U4+ + e \(\rightleftharpoons\) U3+ –0.52
    UO2+ + 4H+ + e\(\rightleftharpoons\)U4+ + 2H2O(l) 0.27
    UO22+ + e\(\rightleftharpoons\)UO2+ 0.16
    UO22+ + 4H+ + 2e\(\rightleftharpoons\) U4+ + 2H2O(l) 0.327
    Vanadium E° (V)
    \[V^{2+} + 2e^− \rightleftharpoons V(s)\] –1.13
    V3+ + e \(\rightleftharpoons\) V2+ –0.255
    VO2+ + 2H+ +e \(\rightleftharpoons\)V3+ + H2O(l) 0.337
    VO22+ + 2H+ +e \(\rightleftharpoons\) VO2+ + H2O(l) 1.000
    Zinc E° (V)
    Zn2+(aq) + 2e− \(\rightleftharpoons\) Zn(s) –0.7618
    Zn(OH)42− + 2e \(\rightleftharpoons\) Zn(s) + 4OH –1.285
    Zn(NH3)42+ + 2e \(\rightleftharpoons\) Zn(s) + 4NH3 –1.04
    Zn(CN)42− + 2e \(\rightleftharpoons\) Zn(s) + 4CN –1.34