Electrochemical Series

Reaction E°/V As + 3 H+ + 3 e ⇌ AsH3 –0.608 As2O3 + 6 H+ + 6 e ⇌ 2 As + 3 H2O 0.234 HAsO2 + 3 H+ + 3 e ⇌ As + 2 H2O 0.248 AsO2-+ 2 H2O + 3 e ⇌ As + 4 OH-–0.68 H3AsO4 + 2 H+ + 2 e-⇌ HAsO2 + 2 H2O 0.560 AsO43-+ 2 H2O + 2 e ⇌ AsO2-+ 4 OH-–0.71 At2 + 2 e ⇌ 2 At-0.3 Au+ + e ⇌ Au 1.692 Au3+ + 2 e ⇌ Au+ 1.401 Au3+ + 3 e ⇌ Au 1.498 Au2+ + e – ⇌ Au+ 1.8 AuOH2+ + H+ + 2 e ⇌ Au+ + H2O 1.32 AuBr2-+ e ⇌ Au + 2 Br-0.959 AuBr4-+ 3 e ⇌ Au + 4 Br-0.854 AuCl4-+ 3 e ⇌ Au + 4 Cl-1.002 Au(OH)3 + 3 H+ + 3 e ⇌ Au + 3 H2O 1.45 H2BO3-+ 5 H2O + 8 e ⇌ BH4-+ 8 OH-–1.24 H2BO3-+ H2O + 3 e ⇌ B + 4 OH-–1.79 H3BO3 + 3 H+ + 3 e ⇌ B + 3 H2O –0.8698 B(OH)3 + 7 H+ + 8 e ⇌ BH4-+ 3 H2O –0.481 Ba2+ + 2 e ⇌ Ba –2.912 Ba2+ + 2 e ⇌ Ba(Hg) –1.570 Ba(OH)2 + 2 e ⇌ Ba + 2 OH-–2.99 Be2+ + 2 e ⇌ Be –1.847 Be2O32-+ 3 H2O + 4 e ⇌ 2 Be + 6 OH-–2.63 p-benzoquinone + 2 H+ + 2 e ⇌

hydroquinone 0.6992

Bi+ + e ⇌ Bi 0.5 Bi3+ + 3 e ⇌ Bi 0.308 Bi3+ + 2 e ⇌ Bi+ 0.2 Bi + 3 H+ + 3 e ⇌ BiH3 –0.8 BiCl4-+ 3 e ⇌ Bi + 4 Cl-0.16 Bi2O3 + 3 H2O + 6 e ⇌ 2 Bi + 6 OH-–0.46 Bi2O4 + 4 H+ + 2 e ⇌ 2 BiO+ + 2 H2O 1.593 BiO+ + 2 H+ + 3 e ⇌ Bi + H2O 0.320 BiOCl + 2 H+ + 3 e ⇌ Bi + Cl-+ H2O 0.1583 Bk4+ + e ⇌ Bk3+ 1.67 Bk2+ + 2 e ⇌ Bk –1.6 Bk3+ + e ⇌ Bk2+ –2.8

Br2(aq) + 2 e ⇌ 2 Br-1.0873 Br2(l) + 2 e ⇌ 2 Br-1.066 HBrO + H+ + 2 e ⇌ Br-+ H2O 1.331 HBrO + H+ + e ⇌ 1/2 Br2(aq) + H2O 1.574 HBrO + H+ + e ⇌ 1/2 Br2(l) + H2O 1.596 BrO-+ H2O + 2 e ⇌ Br-+ 2 OH-0.761 BrO3-+ 6 H+ + 5 e ⇌ 1/2 Br2 + 3 H2O 1.482 BrO3-+ 6 H+ + 6 e ⇌ Br-+ 3 H2O 1.423 BrO3-+ 3 H2O + 6 e ⇌ Br-+ 6 OH-0.61 (CN)2 + 2 H+ + 2 e ⇌ 2 HCN 0.373 2 HCNO + 2 H+ + 2 e ⇌ (CN)2 + 2 H2O 0.330 (CNS)2 + 2 e ⇌ 2 CNS-0.77 CO2 + 2 H+ + 2 e ⇌ HCOOH –0.199 Ca+ + e ⇌ Ca –3.80 Ca2+ + 2 e ⇌ Ca –2.868 Ca(OH)2 + 2 e ⇌ Ca + 2 OH-–3.02 Calomel electrode, 1 molal KCl 0.2800 Calomel electrode, 1 molar KCl (NCE) 0.2801 Calomel electrode, 0.1 molar KCl 0.3337 Calomel electrode, saturated KCl (SCE) 0.2412 Calomel electrode, saturated NaCl (SSCE) 0.2360 Cd2+ + 2 e ⇌ Cd –0.4030 Cd2+ + 2 e ⇌ Cd(Hg) –0.3521 Cd(OH)2 + 2 e ⇌ Cd(Hg) + 2 OH-–0.809 CdSO4 + 2 e ⇌ Cd + SO42-–0.246 Cd(OH)42-+ 2 e ⇌ Cd + 4 OH-–0.658 CdO + H2O + 2 e ⇌ Cd + 2 OH-–0.783 Ce3+ + 3 e ⇌ Ce –2.336 Ce3+ + 3 e ⇌ Ce(Hg) –1.4373 Ce4+ + e ⇌ Ce3+ 1.72 CeOH3+ + H+ + e ⇌ Ce3+ + H2O 1.715 Cf4+ + e ⇌ Cf3+ 3.3 Cf3+ + e ⇌ Cf2+ –1.6 Cf3+ + 3 e ⇌ Cf –1.94 Cf2+ + 2 e ⇌ Cf –2.12 Cl2(g) + 2 e ⇌ 2 Cl-1.35827 HClO + H + + e ⇌ 1/2 Cl2 + H2O 1.611 HClO + H+ + 2 e ⇌ Cl-+ H2O 1.482 ClO-+ H2O + 2 e ⇌ Cl-+ 2 OH-0.81 ClO2 + H+ + e ⇌ HClO2 1.277 HClO2 + 2 H+ + 2 e ⇌ HClO + H2O 1.645 HClO2 + 3 H+ + 3 e ⇌ 1/2 Cl2 + 2 H2O 1.628 HClO2 + 3 H+ + 4 e ⇌ Cl-+ 2 H2O 1.570 ClO2-+ H2O + 2 e ⇌ ClO-+ 2 OH-0.66 ClO2-+ 2 H2O + 4 e ⇌ Cl-+ 4 OH-0.76 ClO2(aq) + e ⇌ ClO2-0.954 ClO3-+ 2 H+ + e ⇌ ClO2 + H2O 1.152 ClO3-+ 3 H+ + 2 e ⇌ HClO2 + H2O 1.214 ClO3-+ 6 H+ + 5 e ⇌ 1/2 Cl2 + 3 H2O 1.47 ClO3-+ 6 H+ + 6 e ⇌ Cl-+ 3 H2O 1.451 ClO3-+ H2O + 2 e ⇌ ClO2-+ 2 OH-0.33 ClO3-+ 3 H2O + 6 e ⇌ Cl-+ 6 OH-0.62 ClO4-+ 2 H+ + 2 e ⇌ ClO3-H2O 1.189 ClO4-+ 8 H+ + 7 e ⇌ 1/2 Cl2 + 4 H2O 1.39 ClO4-+ 8 H+ + 8 e ⇌ Cl-+ 4 H2O 1.389 ClO4-+ H2O + 2 e ⇌ ClO3-+ 2 OH-0.36 Cm4+ + e ⇌ Cm3+ 3.0 Cm3+ + 3 e ⇌ Cm –2.04 Co2+ + 2 e ⇌ Co –0.28 3+2+

[Co(NH3)6]3+ + e ⇌ [Co(NH3)6]2+ 0.108 Co(OH)2 + 2 e ⇌ Co + 2 OH-–0.73 Co(OH)3 + e ⇌ Co(OH)2 + OH-0.17 Cr2+ + 2 e ⇌ Cr –0.913 Cr3+ + e ⇌ Cr2+ –0.407 Cr3+ + 3 e ⇌ Cr –0.744 Cr2O72-+ 14 H+ + 6 e ⇌ 2 Cr3+ + 7 H2O 1.36 CrO2-+ 2 H2O + 3 e ⇌ Cr + 4 OH-–1.2 HCrO4-+ 7 H+ + 3 e ⇌ Cr3+ + 4 H2O 1.350 CrO2 + 4 H+ + e ⇌ Cr3+ +2H2O 1.48 Cr(V) + e ⇌ Cr(IV) 1.34 CrO42-+ 4 H2O + 3 e ⇌ Cr(OH)3 + 5 OH-–0.13 Cr(OH)3 + 3 e ⇌ Cr + 3 OH-–1.48 Cs+ + e ⇌ Cs –3.026 Cu+ + e ⇌ Cu 0.521 Cu2+ + e ⇌ Cu+ 0.153 Cu2+ + 2 e ⇌ Cu 0.3419 Cu2+ + 2 e ⇌ Cu(Hg) 0.345 Cu3+ + e ⇌ Cu2+ 2.4 Cu2O3 + 6 H+ + 2e ⇌ 2Cu2+ + 3 H2O 2.0 Cu2+ + 2 CN-+ e ⇌ [Cu(CN)2]– 1.103 CuI2-+ e ⇌ Cu + 2 I-0.00 Cu2O + H2O + 2 e ⇌ 2 Cu + 2 OH-–0.360 Cu(OH)2 + 2 e ⇌ Cu + 2 OH-–0.222 2 Cu(OH)2 + 2 e ⇌ Cu2O + 2 OH-+ H2O –0.080 2 D+ + 2 e ⇌ D2 –0.013 Dy2+ + 2 e ⇌ Dy –2.2 Dy3+ + 3 e ⇌ Dy –2.295 Dy3+ + e ⇌ Dy2+ –2.6 Er2+ + 2 e ⇌ Er –2.0 Er3+ + 3 e ⇌ Er –2.331 Er3+ + e ⇌ Er2+ –3.0 Es3+ + e ⇌ Es2+ –1.3 Es3+ + 3 e ⇌ Es –1.91 Es2+ + 2 e ⇌ Es –2.23 Eu2+ + 2 e ⇌ Eu –2.812 Eu3+ + 3 e ⇌ Eu –1.991 Eu3+ + e ⇌ Eu2+ –0.36 F2 + 2 H+ + 2 e ⇌ 2 HF 3.053 F2 + 2 e ⇌ 2 F-2.866 F2O + 2 H+ + 4 e ⇌ H2O + 2 F-2.153 Fe2+ + 2 e ⇌ Fe –0.447 Fe3+ + 3 e ⇌ Fe –0.037 Fe3+ + e ⇌ Fe2+ 0.771 2 HFeO4-+ 8 H+ + 6 e ⇌ Fe2O3 + 5 H2O 2.09 HFeO4-+ 4 H+ + 3 e ⇌ FeOOH + 2 H2O 2.08 HFeO4-+ 7 H+ + 3 e ⇌ Fe3+ + 4 H2O 2.07 Fe2O3 + 4 H+ + 2 e ⇌ 2 FeOH+ + H2O 0.16 [Fe(CN)6]3-+ e ⇌ [Fe(CN)6]4-0.358 FeO42-+ 8 H+ + 3 e Fe3+ + 4 H2O 2.20 [Fe(bipy)2]3+ + e ⇌ Fe(bipy)2]2+ 0.78 [Fe(bipy)3]3+ + e ⇌ Fe(bipy)3]2+ 1.03 Fe(OH)3 + e ⇌ Fe(OH)2 + OH-–0.56 [Fe(phen)3]3+ + e ⇌ [Fe(phen)3]2+ 1.147 [Fe(phen)3]3+ + e ⇌ [Fe(phen)3]2+ (1 molar

H2SO4) 1.06 [Ferricinium]+ + e ⇌ ferrocene 0.400 Fm3++ e ⇌ Fm2+ –1.1 Fm3+ + 3 e ⇌ Fm –1.89

Fr+ + e ⇌ Fr –2.9 Ga3+ + 3 e ⇌ Ga –0.549 Ga+ + e ⇌ Ga –0.2 GaOH2+ + H+ + 3 e ⇌ Ga + H2O –0.498 H2GaO-3 + H2O + 3 e ⇌ Ga + 4 OH-–1.219 Gd3+ + 3 e ⇌ Gd –2.279 Ge2+ + 2 e ⇌ Ge 0.24 Ge4+ + 4 e ⇌ Ge 0.124 Ge4+ + 2 e ⇌ Ge2+ 0.00 GeO2 + 2 H+ + 2 e ⇌ GeO + H2O –0.118 H2GeO3 + 4 H+ + 4 e ⇌ Ge + 3 H2O –0.182 2 H+ + 2 e ⇌ H2 0.00000 H2 + 2 e ⇌ 2 H-–2.23 HO2 + H+ + e ⇌ H2O2 1.495 2 H2O + 2 e ⇌ H2 + 2 OH-–0.8277 H2O2 + 2 H+ + 2 e ⇌ 2 H2O 1.776 Hf4+ + 4 e ⇌ Hf –1.55 HfO2+ + 2 H+ + 4 e ⇌ Hf + H2O –1.724 HfO2 + 4 H+ + 4 e ⇌ Hf + 2 H2O –1.505 HfO(OH)2 + H2O + 4 e ⇌ Hf + 4 OH-–2.50 Hg2+ + 2 e ⇌ Hg 0.851 2 Hg2+ + 2 e ⇌ Hg22+ 0.920 Hg22+ + 2 e ⇌ 2 Hg 0.7973 Hg2(ac)2 + 2 e ⇌ 2 Hg + 2(ac)– 0.51163 Hg2Br2 + 2 e ⇌ 2 Hg + 2 Br-0.13923 Hg2Cl2 + 2 e ⇌ 2 Hg + 2 Cl-0.26808 Hg2HPO4 + 2 e ⇌ 2 Hg + HPO42-0.6359 Hg2I2 + 2 e ⇌ 2 Hg + 2 I-–0.0405 Hg2O + H2O + 2 e ⇌ 2 Hg + 2 OH-0.123 HgO + H2O + 2 e ⇌ Hg + 2 OH-0.0977 Hg(OH)2 + 2 H+ + 2 e ⇌ Hg + 2 H2O 1.034 Hg2SO4 + 2 e ⇌ 2 Hg + SO42-0.6125 Ho2+ + 2 e ⇌ Ho –2.1 Ho3+ + 3 e ⇌ Ho –2.33 Ho3+ + e ⇌ Ho2+ –2.8 I2 + 2 e ⇌ 2 I-0.5355 I3-+ 2 e ⇌ 3 I-0.536 H3IO62-+ 2 e ⇌ IO-3 + 3 OH-0.7 H5IO6 + H+ + 2 e ⇌ IO3-+ 3 H2O 1.601 2 HIO + 2 H+ + 2 e ⇌ I2 + 2 H2O 1.439 HIO + H+ + 2 e ⇌ I-+ H2O 0.987 IO-+ H2O + 2 e ⇌ I-+ 2 OH-0.485 2 IO3-+ 12 H+ + 10 e ⇌ I2 + 6 H2O 1.195 IO3-+ 6 H+ + 6 e ⇌ I-+ 3 H2O 1.085 IO3-+ 2 H2O + 4 e ⇌ IO-+ 4 OH-0.15 IO3-+ 3 H2O + 6 e ⇌ IO-+ 6 OH-0.26 In+ + e ⇌ In –0.14 In2+ + e ⇌ In+ –0.40 In3+ + e ⇌ In2+ –0.49 In3+ + 2 e ⇌ In+ –0.443 In3+ + 3 e ⇌ In –0.3382 In(OH)3 + 3 e ⇌ In + 3 OH-–0.99 In(OH)4-+ 3 e ⇌ In + 4 OH-–1.007 In2O3 + 3 H2O + 6 e ⇌ 2 In + 6 OH-–1.034 Ir3+ + 3 e ⇌ Ir 1.156 [IrCl6]2-+ e ⇌ [IrCl6]3-0.8665 [IrCl6]3-+ 3 e ⇌ Ir + 6 Cl-0.77 Ir2O3 + 3 H2O + 6 e ⇌ 2 Ir + 6 OH-0.098 K+ + e ⇌ K –2.931

La(OH)3 + 3 e ⇌ La + 3 OH-–2.90 Li+ + e ⇌ Li –3.0401 Lr3+ + 3 e ⇌ Lr –1.96 Lu3+ + 3 e ⇌ Lu –2.28 Md3+ + e ⇌ Md2+ –0.1 Md3+ + 3 e ⇌ Md –1.65 Md2+ + 2 e ⇌ Md –2.40 Mg+ + e ⇌ Mg –2.70 Mg2+ + 2 e ⇌ Mg –2.372 Mg(OH)2 + 2 e ⇌ Mg + 2 OH-–2.690 Mn2+ + 2 e ⇌ Mn –1.185 Mn3+ + e ⇌ Mn2+ 1.5415 MnO2 + 4 H+ + 2 e ⇌ Mn2+ + 2 H2O 1.224 MnO4-+ e ⇌ MnO42-0.558 MnO4-+ 4 H+ + 3 e ⇌ MnO2 + 2 H2O 1.679 MnO4-+ 8 H+ + 5 e ⇌ Mn2+ + 4 H2O 1.507 MnO4-+ 2 H2O + 3 e ⇌ MnO2 + 4 OH-0.595 MnO42-+ 2 H2O + 2 e ⇌ MnO2 + 4 OH-0.60 Mn(OH)2 + 2 e ⇌ Mn + 2 OH-–1.56 Mn(OH)3 + e ⇌ Mn(OH)2 + OH-0.15 Mn2O3 + 6 H+ + e ⇌ 2 Mn2+ + 3 H2O 1.485 Mo3+ + 3 e ⇌ Mo –0.200 MoO2 + 4 H+ + 4 e ⇌ Mo + 4 H2O –0.152 H3Mo7O243-+ 45 H+ + 42 e ⇌ 7 Mo + 24 H2O 0.082 MoO3 + 6 H+ + 6 e ⇌ Mo + 3 H2O 0.075 N2 + 2 H2O + 6 H+ + 6 e ⇌ 2 NH4OH 0.092 3 N2 + 2 H+ + 2 e ⇌ 2 HN3 –3.09 N5+ + 3 H+ + 2 e ⇌ 2 NH4+ 1.275 N2O + 2 H+ + 2 e ⇌ N2 + H2O 1.766 H2N2O2 + 2 H+ + 2 e ⇌ N2 + 2 H2O 2.65 N2O4 + 2 e ⇌ 2 NO2-0.867 N2O4 + 2 H+ + 2 e ⇌ 2 NHO2 1.065 N2O4 + 4 H+ + 4 e ⇌ 2 NO + 2 H2O 1.035 2 NH3OH+ + H+ + 2 e ⇌ N2H5+ + 2 H2O 1.42 2 NO + 2 H+ + 2 e ⇌ N2O + H2O 1.591 2 NO + H2O + 2 e ⇌ N2O + 2 OH-0.76 HNO2 + H+ + e ⇌ NO + H2O 0.983 2 HNO2 + 4 H+ + 4 e ⇌ H2N2O2 + 2 H2O 0.86 2 HNO2 + 4 H+ + 4 e ⇌ N2O + 3 H2O 1.297 NO2-+ H2O + e ⇌ NO + 2 OH-–0.46 2 NO2-+ 2 H2O + 4 e ⇌ N2O22-+ 4 OH-–0.18 2 NO2-+ 3 H2O + 4 e ⇌ N2O + 6 OH-0.15 NO3-+ 3 H+ + 2 e ⇌ HNO2 + H2O 0.934 NO3-+ 4 H+ + 3 e ⇌ NO + 2 H2O 0.957 2 NO3-+ 4 H+ + 2 e ⇌ N2O4 + 2 H2O 0.803 NO3-+ H2O + 2 e ⇌ NO2-+ 2 OH-0.01 2 NO3-+ 2 H2O + 2 e ⇌ N2O4 + 4 OH-–0.85 Na+ + e ⇌ Na –2.71 Nb3+ + 3 e ⇌ Nb –1.099 NbO2 + 2 H+ + 2 e ⇌ NbO + H2O –0.646 NbO2 + 4 H+ + 4 e ⇌ Nb + 2 H2O –0.690 NbO + 2 H+ + 2 e ⇌ Nb + H2O –0.733 Nb2O5 + 10 H+ + 10 e ⇌ 2 Nb + 5 H2O –0.644 Nd3+ + 3 e ⇌ Nd –2.323 Nd2+ + 2 e ⇌ Nd –2.1 Nd3+ + e ⇌ Nd2+ –2.7 Ni2+ + 2 e ⇌ Ni –0.257 Ni(OH)2 + 2 e ⇌ Ni + 2 OH-–0.72 NiO2 + 4 H+ + 2 e ⇌ Ni2+ + 2 H2O 1.678

No3+ + e ⇌ No2+ 1.4 No3+ + 3 e ⇌ No –1.20 No2+ + 2 e ⇌ No –2.50 Np3+ + 3 e ⇌ Np –1.856 Np4+ + e ⇌ Np3+ 0.147 NpO2 + H2O + H+ + e ⇌ Np(OH)3 –0.962 O2 + 2 H+ + 2 e ⇌ H2O2 0.695 O2 + 4 H+ + 4 e ⇌ 2 H2O 1.229 O2 + H2O + 2 e ⇌ HO2-+ OH-–0.076 O2 + 2 H2O + 2 e ⇌ H2O2 + 2 OH-–0.146 O2 + 2 H2O + 4 e ⇌ 4 OH-0.401 O3 + 2 H+ + 2 e ⇌ O2 + H2O 2.076 O3 + H2O + 2 e ⇌ O2 + 2 OH-1.24 O(g) + 2 H+ + 2 e ⇌ H2O 2.421 OH + e ⇌ OH-2.02 HO2-+ H2O + 2 e ⇌ 3 OH-0.878 OsO4 + 8 H+ + 8 e ⇌ Os + 4 H2O 0.838 OsO4 + 4 H+ + 4 e ⇌ OsO2 + 2 H2O 1.02 [Os(bipy)2]3+ + e ⇌ [Os(bipy)2]2+ 0.81 [Os(bipy)3]3+ + e ⇌ [Os(bipy)3]2+ 0.80 P(red) + 3 H+ + 3 e ⇌ PH3(g) –0.111 P(white) + 3 H+ + 3 e ⇌ PH3(g) –0.063 P + 3 H2O + 3 e ⇌ PH3(g) + 3 OH-–0.87 H2P2-+ e ⇌ P + 2 OH-–1.82 H3PO2 + H+ + e ⇌ P + 2 H2O –0.508 H3PO3 + 2 H+ + 2 e ⇌ H3PO2 + H2O –0.499 H3PO3 + 3 H+ + 3 e ⇌ P + 3 H2O –0.454 HPO32-+ 2 H2O + 2 e ⇌ H2PO2-+ 3 OH-–1.65 HPO32-+ 2 H2O + 3 e ⇌ P + 5 OH-–1.71 H3PO4 + 2 H+ + 2 e ⇌ H3PO3 + H2O –0.276 PO43-+ 2 H2O + 2 e ⇌ HPO32-+ 3 OH-–1.05 Pa3+ + 3 e ⇌ Pa –1.34 Pa4+ + 4 e ⇌ Pa –1.49 Pa4+ + e ⇌ Pa3+ –1.9 Pb2+ + 2 e ⇌ Pb –0.1262 Pb2+ + 2 e ⇌ Pb(Hg) –0.1205 PbBr2 + 2 e ⇌ Pb + 2 Br-–0.284 PbCl2 + 2 e ⇌ Pb + 2 Cl-–0.2675 PbF2 + 2 e ⇌ Pb + 2 F-–0.3444 PbHPO4 + 2 e ⇌ Pb + HPO42-–0.465 PbI2 + 2 e ⇌ Pb + 2 I-–0.365 PbO + H2O + 2 e ⇌ Pb + 2 OH-–0.580 PbO2 + 4 H+ + 2 e ⇌ Pb2+ + 2 H2O 1.455 HPbO2-+ H2O + 2 e ⇌ Pb + 3 OH-–0.537 PbO2 + H2O + 2 e ⇌ PbO + 2 OH-0.247 PbO2 + SO42-+ 4 H+ + 2 e ⇌ PbSO4 + 2 H2O 1.6913 PbSO4 + 2 e ⇌ Pb + SO42-–0.3588 PbSO4 + 2 e ⇌ Pb(Hg) + SO42-–0.3505 Pd2+ + 2 e ⇌ Pd 0.951 [PdCl4]2-+ 2 e ⇌ Pd + 4 Cl-0.591 [PdCl6]2-+ 2 e ⇌ [PdCl4]2-+ 2 Cl-1.288 Pd(OH)2 + 2 e ⇌ Pd + 2 OH-0.07 Pm2+ + 2 e ⇌ Pm –2.2 Pm3+ + 3 e ⇌ Pm –2.30 Pm3+ + e ⇌ Pm2+ –2.6 Po4+ + 2 e ⇌ Po2+ 0.9 Po4+ + 4 e ⇌ Po 0.76 Pr4+ + e ⇌ Pr3+ 3.2 Pr2+ + 2 e ⇌ Pr –2.0

Pr3+ + e ⇌ Pr2+ –3.1 Pt2+ + 2 e ⇌ Pt 1.18 [PtCl4]2-+ 2 e ⇌ Pt + 4 Cl-0.755 [PtCl6]2-+ 2 e ⇌ [PtCl4]2-+ 2 Cl-0.68 Pt(OH)2 + 2 e ⇌ Pt + 2 OH-0.14 PtO3 + 2 H+ + 2 e ⇌ PtO2 + H2O 1.7 PtO3 + 4 H+ + 2 e ⇌ Pt(OH)22+ + H2O 1.5 PtOH+ + H+ + 2 e ⇌ Pt + H2O 1.2 PtO2 + 2 H+ + 2 e ⇌ PtO + H2O 1.01 PtO2 + 4 H+ + 4 e ⇌ Pt + 2 H2O 1.00 Pu3+ + 3 e ⇌ Pu –2.031 Pu4+ + e ⇌ Pu3+ 1.006 Pu5+ + e ⇌ Pu4+ 1.099 PuO2(OH)2 + 2 H+ + 2 e ⇌ Pu(OH)4 1.325 PuO2(OH)2 + H+ + e ⇌ PuO2OH + H2O 1.062 Ra2+ + 2 e ⇌ Ra –2.8 Rb+ + e ⇌ Rb –2.98 Re3+ + 3 e ⇌ Re 0.300 ReO4-+ 4 H+ + 3 e ⇌ ReO2 + 2 H2O 0.510 ReO2 + 4 H+ + 4 e ⇌ Re + 2 H2O 0.2513 ReO4-+ 2 H+ + e ⇌ ReO3 + H2O 0.768 ReO4-+ 4 H2O + 7 e ⇌ Re + 8 OH-–0.584 ReO4-+ 8 H+ + 7 e ⇀ Re + 4 H2O 0.368 Rh+ + e ⇌ Rh 0.600 Rh3+ + 3 e ⇌ Rh 0.758 [RhCl6]3-+ 3 e ⇌ Rh + 6 Cl-0.431 RhOH2+ + H+ + 3 e ⇌ Rh + H2O 0.83 Ru2+ + 2 e ⇌ Ru 0.455 Ru3+ + e ⇌ Ru2+ 0.2487 RuO2 + 4 H+ + 2 e ⇌ Ru2+ + 2 H2O 1.120 RuO4-+ e ⇌ RuO42-0.59 RuO4 + e ⇌ RuO4-1.00 RuO4 + 6 H+ + 4 e ⇌ Ru(OH)22+ + 2 H2O 1.40 RuO4 + 8 H+ + 8 e ⇌ Ru + 4 H2O 1.038 [Ru(bipy)3)3+ + e-⇌ [Ru(bipy)3]2+ 1.24 [Ru(H2O)6]3+ + e-⇌ [Ru(H2O)6]2+ 0.23 [Ru(NH3)6]3+ + e-⇌ [Ru(NH3)6]2+ 0.10 [Ru(en)3]3+ + e – ⇌ [Ru(en)3]2+ 0.210 [Ru(CN)6]3-+ e-⇌ [Ru(CN)6]4-0.86 S + 2 e ⇌ S2-–0.47627 S + 2H+ + 2 e ⇌ H2S(aq) 0.142 S + H2O + 2 e ⇌ SH-+ OH-–0.478 2 S + 2 e ⇌ S22-–0.42836 S2O62-+ 4 H+ + 2 e ⇌ 2 H2SO3 0.564 S2O82-+ 2 e ⇌ 2 SO42-2.010 S2O82-+ 2 H+ + 2 e ⇌ 2 HSO4-2.123 S4O62-+ 2 e ⇌ 2 S2O32-0.08 2 H2SO3 + H+ + 2 e ⇌ HS2O4-+ 2 H2O –0.056 H2SO3 + 4 H+ + 4 e ⇌ S + 3 H2O 0.449 2 SO32-+ 2 H2O + 2 e ⇌ S2O42-+ 4 OH-–1.12 2 SO32-+ 3 H2O + 4 e ⇌ S2O32-+ 6 OH-–0.571 SO42-+ 4 H+ + 2 e ⇌ H2SO3 + H2O 0.172 2 SO42-+ 4 H+ + 2 e ⇌ S2O62-+ H2O –0.22 SO42-+ H2O + 2 e ⇌ SO32-+ 2 OH-–0.93 Sb + 3 H+ + 3 e ⇌ SbH3 –0.510 Sb2O3 + 6 H+ + 6 e ⇌ 2 Sb + 3 H2O 0.152 Sb2O5 (senarmontite) + 4 H+ + 4 e ⇌ Sb2O3 +

2 H2O 0.671

Sb2O5 (valentinite) + 4 H+ + 4 e ⇌ Sb2O3 + 2

0.649

Sb2O5 + 6 H+ + 4 e ⇌ 2 SbO+ + 3 H2O 0.581 SbO+ + 2 H+ + 3 e ⇌ Sb + 2 H2O 0.212 SbO2-+ 2 H2O + 3 e ⇌ Sb + 4 OH-–0.66 SbO3-+ H2O + 2 e ⇌ SbO2-+ 2 OH-–0.59 Sc3+ + 3 e ⇌ Sc –2.077 Se + 2 e ⇌ Se2-–0.924 Se + 2 H+ + 2 e ⇌ H2Se(aq) –0.399 H2SeO3 + 4 H+ + 4 e ⇌ Se + 3 H2O 0.74 Se + 2 H+ + 2 e ⇌ H2Se –0.082 SeO32-+ 3 H2O + 4 e ⇌ Se + 6 OH-–0.366 SeO42-+ 4 H+ + 2 e ⇌ H2SeO3 + H2O 1.151 SeO42-+ H2O + 2 e ⇌ SeO32-+ 2 OH-0.05 SiF62-+ 4 e ⇌ Si + 6 F-–1.24 SiO + 2 H+ + 2 e ⇌ Si + H2O –0.8 SiO2 (quartz) + 4 H+ + 4 e ⇌ Si + 2 H2O 0.857 SiO32-+ 3 H2O + 4 e ⇌ Si + 6 OH-–1.697 Sm3+ + e ⇌ Sm2+ –1.55 Sm3+ + 3 e ⇌ Sm –2.304 Sm2+ + 2 e ⇌ Sm –2.68 Sn2+ + 2 e ⇌ Sn –0.1375 Sn4+ + 2 e ⇀ Sn2+ 0.151 Sn(OH)3+ + 3 H+ + 2 e ⇌ Sn2+ + 3 H2O 0.142 SnO2 + 4 H+ + 2 e-⇌ Sn2+ + 2 H2O –0.094 SnO2 + 4 H+ + 4 e ⇌ Sn + 2 H2O –0.117 SnO2 + 3 H+ + 2 e ⇌ SnOH+ + H2O –0.194 SnO2 + 2 H2O + 4 e ⇌ Sn + 4 OH-–0.945 HSnO2-+ H2O + 2 e ⇌ Sn + 3 OH-–0.909 Sn(OH)62-+ 2 e ⇌ HSnO2-+ 3 OH-+ H2O –0.93 Sr+ + e ⇌ Sr –4.10 Sr2+ + 2 e ⇌ Sr –2.899 Sr2+ + 2 e ⇌ Sr(Hg) –1.793 Sr(OH)2 + 2 e ⇌ Sr + 2 OH-–2.88 Ta2O5 + 10 H+ + 10 e ⇌ 2 Ta + 5 H2O –0.750 Ta3+ + 3 e ⇌ Ta –0.6 Tc2+ + 2 e ⇌ Tc 0.400 TcO4-+ 4 H+ + 3 e ⇌ TcO2 + 2 H2O 0.782 Tc3+ + e ⇌ Tc2+ 0.3 TcO4-+ 8 H+ + 7 e ⇌ Tc + 4 H2O 0.472 Tb4+ + e ⇌ Tb3+ 3.1 Tb3+ + 3 e ⇌ Tb –2.28 Te + 2 e ⇌ Te2-–1.143 Te + 2 H+ + 2 e ⇌ H2Te –0.793 Te4+ + 4 e ⇌ Te 0.568 TeO2 + 4 H+ + 4 e ⇌ Te + 2 H2O 0.593 TeO32-+ 3 H2O + 4 e ⇌ Te + 6 OH-–0.57 TeO4-+ 8 H+ + 7 e ⇌ Te + 4 H2O 0.472 H6TeO6 + 2 H+ + 2 e ⇌ TeO2 + 4 H2O 1.02 Th4+ + 4 e ⇌ Th –1.899 ThO2 + 4 H+ + 4 e ⇌ Th + 2 H2O –1.789 Th(OH)4 + 4 e ⇌ Th + 4 OH-–2.48 Ti2+ + 2 e ⇌ Ti –1.630 Ti3+ + e ⇌ Ti2+ –0.9 TiO2 + 4 H+ + 2 e ⇌ Ti2+ + 2 H2O –0.502 Ti3+ + 3 e ⇌ Ti –1.37 TiOH3+ + H+ + e ⇌ Ti3+ + H2O –0.055

Tl+ + e ⇌ Tl –0.336 Tl+ + e ⇌ Tl(Hg) –0.3338 Tl3+ + 2 e ⇌ Tl+ 1.252 Tl3+ + 3 e ⇌ Tl 0.741 TlBr + e ⇌ Tl + Br-–0.658 TlCl + e ⇌ Tl + Cl-–0.5568 TlI + e ⇌ Tl + I-–0.752 Tl2O3 + 3 H2O + 4 e ⇌ 2 Tl+ + 6 OH-0.02 TlOH + e ⇌ Tl + OH-–0.34 Tl(OH)3 + 2 e ⇌ TlOH + 2 OH-–0.05 Tl2SO4 + 2 e ⇌ Tl + SO42-–0.4360 Tm3+ + e ⇌ Tm2+ –2.2 Tm3+ + 3 e ⇌ Tm –2.319 Tm2+ + 2 e ⇌ Tm –2.4 U3+ + 3 e ⇌ U –1.798 U4+ + e ⇌ U3+ –0.607 UO2+ + 4 H+ + e ⇌ U4+ + 2 H2O 0.612 UO22+ + e ⇌ UO+2 0.062 UO22+ + 4 H+ + 2 e ⇌ U4+ + 2 H2O 0.327 UO22+ + 4 H+ + 6 e ⇌ U + 2 H2O –1.444 V2+ + 2 e ⇌ V –1.175 V3+ + e ⇌ V2+ –0.255 VO2+ + 2 H+ + e ⇌ V3+ + H2O 0.337 VO2+ + 2 H+ + e ⇌ VO2+ + H2O 0.991 V2O5 + 6 H+ + 2 e ⇌ 2 VO2+ + 3 H2O 0.957 V2O5 + 10 H+ + 10 e ⇌ 2 V + 5 H2O –0.242 V(OH)4+ + 2 H+ + e ⇌ VO2+ + 3 H2O 1.00 V(OH)4+ + 4 H+ + 5 e ⇌ V + 4 H2O –0.254 [V(phen)3]3+ + e ⇌ [V(phen)3]2+ 0.14 W3+ + 3 e ⇌ W 0.1 W2O5 + 2 H+ + 2 e ⇌ 2 WO2 + H2O –0.031 WO2 + 4 H+ + 4 e ⇌ W + 2 H2O –0.119 WO3 + 6 H+ + 6 e ⇌ W + 3 H2O –0.090 WO3 + 2 H+ + 2 e ⇌ WO2 + H2O 0.036 2 WO3 + 2 H+ + 2 e ⇌ W2O5 + H2O –0.029 H4XeO6 + 2 H+ + 2 e ⇌ XeO3 + 3 H2O 2.42 XeO3 + 6 H+ + 6 e ⇌ Xe + 3 H2O 2.10 XeF + e ⇌ Xe + F-3.4 Y3+ + 3 e ⇌ Y –2.372 Yb3+ + e ⇌ Yb2+ –1.05 Yb3+ + 3 e ⇌ Yb –2.19 Yb2+ + 2 e ⇌ Yb –2.76 Zn2+ + 2 e ⇌ Zn –0.7618 Zn2+ + 2 e ⇌ Zn(Hg) –0.7628 ZnO22-+ 2 H2O + 2 e ⇌ Zn + 4 OH-–1.215 ZnSO4 · 7 H2O + 2 e = Zn(Hg) + SO42-+ 7

H2O (Saturated ZnSO4) –0.7993

ZnOH+ + H+ + 2 e ⇌ Zn + H2O –0.497 Zn(OH)42-+ 2 e ⇌ Zn + 4 OH-–1.199 Zn(OH)2 + 2 e ⇌ Zn + 2 OH-–1.249 ZnO + H2O + 2 e ⇌ Zn + 2 OH-–1.260 ZrO2 + 4 H+ + 4 e ⇌ Zr + 2 H2O –1.553 ZrO(OH)2 + H2O + 4 e ⇌ Zr + 4 OH-–2.36 Zr4+ + 4 e ⇌ Zr –1.45

Reaction E°/V 2 H+ + 2 e ⇌ H2 0.00000 CuI2-+ e ⇌ Cu + 2 I-0.00 Ge4+ + 2 e ⇌ Ge2+ 0.00 NO3-+ H2O + 2 e ⇌ NO2-+ 2 OH-0.01 Tl2O3 + 3 H2O + 4 e ⇌ 2 Tl+ + 6 OH-0.02 SeO42-+ H2O + 2 e ⇌ SeO32-+ 2 OH-0.05 WO3 + 2 H+ + 2 e ⇌ WO2 + H2O 0.036 UO22+ + e = UO2+ 0.062 Pd(OH)2 + 2 e ⇌ Pd + 2 OH-0.07 AgBr + e ⇌ Ag + Br-0.07133 MoO3 + 6 H+ + 6 e ⇌ Mo + 3 H2O 0.075 S4O62-+ 2 e ⇌ 2 S2O32-0.08 H3Mo7O243-+ 45 H+ + 42 e ⇌ 7 Mo + 24 H2O 0.082 AgSCN + e ⇌ Ag + SCN-0.8951 N2 + 2 H2O + 6 H+ + 6 e ⇌ 2 NH4OH 0.092 HgO + H2O + 2 e ⇌ Hg + 2 OH-0.0977 Ir2O3 + 3 H2O + 6 e ⇌ 2 Ir + 6 OH-0.098 2 NO + 2 e ⇌ N2O22-0.10 [Ru(NH3)6]3+ + e ⇌ [Ru(NH3)6]2+ 0.10 W3+ + 3 e ⇌ W 0.1 [Co(NH3)6]3+ + e ⇌ [Co(NH3)6]2+ 0.108 Hg2O + H2O + 2 e ⇌ 2 Hg + 2 OH-0.123 Ge4+ + 4 e ⇌ Ge 0.124 Hg2Br2 + 2 e ⇌ 2 Hg + 2 Br-0.13923 Pt(OH)2 + 2 e ⇌ Pt + 2 OH-0.14 [V(phen)3]3+ + e ⇌ [V(phen)3]2+ 0.14 S + 2H+ + 2 e ⇌ H2S(aq) 0.142 Sn(OH)3+ + 3 H+ + 2 e ⇌ Sn2+ + 3 H2O 0.142 Np4+ + e ⇌ Np3+ 0.147 Ag4[Fe(CN)6] + 4 e ⇌ 4 Ag + [Fe(CN)6]4-0.1478 IO3-+ 2 H2O + 4 e ⇌ IO-+ 4 OH-0.15 Mn(OH)3 + e ⇌ Mn(OH)2 + OH-0.15 2 NO2-+ 3 H2O + 4 e ⇌ N2O + 6 OH-0.15 Sn4+ + 2 e ⇌ Sn2+ 0.151 Sb2O3 + 6 H+ + 6 e ⇌ 2 Sb + 3 H2O 0.152 Cu2+ + e ⇌ Cu+ 0.153 BiOCl + 2 H+ + 3 e ⇌ Bi + Cl-+ H2O 0.1583 BiCl4-+ 3 e ⇌ Bi + 4 Cl-0.16 Fe2O3 + 4 H+ + 2 e ⇌ 2 FeOH+ + H2O 0.16 Co(OH)3 + e ⇌ Co(OH)2 + OH-0.17 SO42-+ 4 H+ + 2 e ⇌ H2SO3 + H2O 0.172 Bi3+ + 2 e ⇌ Bi+ 0.2 [Ru(en)3]3+ + e ⇌ [Ru(en)3]2+ 0.210 SbO+ + 2 H+ + 3 e ⇌ Sb + 2 H2O 0.212 AgCl + e ⇌ Ag + Cl-0.22233 [Ru(H2O)6]3+ + e ⇌ [Ru(H2O)6]2+ 0.23 As2O3 + 6 H+ + 6 e ⇌ 2 As + 3 H2O 0.234 Calomel electrode, saturated NaCl (SSCE) 0.2360 Ge2+ + 2 e ⇌ Ge 0.24 Ru3+ + e ⇌ Ru2+ 0.24 Calomel electrode, saturated KCl 0.2412 PbO2 + H2O + 2 e ⇌ PbO + 2 OH-0.247 HAsO2 + 3 H+ + 3 e ⇌ As + 2 H2O 0.248 Ru3+ + e ⇀ Ru2+ 0.2487 ReO2 + 4 H+ + 4 e ⇌ Re + 2 H2O 0.2513 –––

Reaction E°/V Hg2Cl2 + 2 e ⇌ 2 Hg + 2 Cl-0.26808 Calomel electrode, 1 molal KCl 0.2800 Calomel electrode, 1 molar KCl (NCE) 0.2801 At2 + 2 e ⇌ 2 At-0.3 Re3+ + 3 e ⇌ Re 0.300 Tc3+ + e ⇌ Tc2+ 0.3 Bi3+ + 3 e ⇌ Bi 0.308 BiO+ + 2 H+ + 3 e ⇌ Bi + H2O 0.320 UO22+ + 4 H+ + 2 e ⇌ U4+ + 2 H2O 0.327 ClO3-+ H2O + 2 e ⇌ ClO2-+ 2 OH-0.33 2 HCNO + 2 H+ + 2 e ⇌ (CN)2 + 2 H2O 0.330 Calomel electrode, 0.1 molar KCl 0.3337 VO2+ + 2 H+ + e ⇌ V3+ + H2O 0.337 Cu2+ + 2 e ⇌ Cu 0.3419 Ag2O + H2O + 2 e ⇌ 2 Ag + 2 OH-0.342 Cu2+ + 2 e ⇌ Cu(Hg) 0.345 AgIO3 + e ⇌ Ag + IO3-0.354 [Fe(CN)6]3-+ e ⇌ [Fe(CN)6]4-0.358 ClO4-+ H2O + 2 e ⇌ ClO-3 + 2 OH-0.36 Ag2SeO3 + 2 e ⇌ 2 Ag + SeO32-0.3629 ReO4-+ 8 H+ + 7 e ⇌ Re + 4 H2O 0.368 (CN)2 + 2 H+ + 2 e ⇌ 2 HCN 0.373 [Ferricinium]+ + e ⇌ ferrocene 0.400 Tc2+ + 2 e ⇌ Tc 0.400 O2 + 2 H2O + 4 e ⇌ 4 OH-0.401 AgOCN + e ⇌ Ag + OCN-0.41 [RhCl6]3-+ 3 e ⇌ Rh + 6 Cl-0.431 Ag2CrO4 + 2 e ⇌ 2 Ag + CrO42-0.4470 H2SO3 + 4 H+ + 4 e ⇌ S + 3 H2O 0.449 Ru2+ + 2 e ⇌ Ru 0.455 Ag2MoO4 + 2 e ⇌ 2 Ag + MoO42-0.4573 Ag2C2O4 + 2 e ⇌ 2 Ag + C2O42-0.4647 Ag2WO4 + 2 e ⇌ 2 Ag + WO42-0.4660 Ag2CO3 + 2 e ⇌ 2 Ag + CO32-0.47 TcO4-+ 8 H+ + 7 e ⇌ Tc + 4 H2O 0.472 TeO4-+ 8 H+ + 7 e ⇌ Te + 4 H2O 0.472 IO-+ H2O + 2 e ⇌ I-+ 2 OH-0.485 NiO2 + 2 H2O + 2 e ⇌ Ni(OH)2 + 2 OH-0.490 Bi+ + e ⇌ Bi 0.5 ReO4-+ 4 H+ + 3 e ⇌ ReO2 + 2 H2O 0.510 Hg2(ac)2 + 2 e ⇌ 2 Hg + 2(ac)– 0.51163 Cu+ + e ⇌ Cu 0.521 I2 + 2 e ⇌ 2 I-0.5355 I3-+ 2 e ⇌ 3 I-0.536 AgBrO3 + e ⇌ Ag + BrO3-0.546 MnO4-+ e ⇌ MnO4-0.558 H3AsO4 + 2 H+ + 2 e ⇌ HAsO2 + 2 H2O 0.560 S2O62-+ 4 H+ + 2 e ⇌ 2 H2SO3 0.564 AgNO2 + e ⇌ Ag + NO2-0.564 Te4+ + 4 e ⇌ Te 0.568 Sb2O5 + 6 H+ + 4 e ⇌ 2 SbO+ + 3 H2O 0.581 RuO4-+ e ⇌ RuO42-0.59 [PdCl4]2-+ 2 e ⇌ Pd + 4 Cl-0.591 TeO2 + 4 H+ + 4 e ⇌ Te + 2 H2O 0.593 MnO4-+ 2 H2O + 3 e ⇌ MnO2 + 4 OH-0.595

H2O 0.671 [PtCl6]2-+ 2 e ⇌ [PtCl4]2-+ 2 Cl-0.68 O2 + 2 H+ + 2 e ⇌ H2O2 0.695 p-benzoquinone + 2 H+ + 2 e ⇌⇌ hydroquinone 0.6992 H3IO62-+ 2 e ⇌ IO3-+ 3 OH-0.7 Ag2O3+ H2O + 2 e ⇌ 2 AgO + 2 OH-0.739 Tl3+ + 3 e ⇌ Tl 0.741 [PtCl4]2-+ 2 e ⇌ Pt + 4 Cl-0.755 Rh3+ + 3 e ⇌ Rh 0.758 ClO2-+ 2 H2O + 4 e ⇌ Cl-+ 4 OH-0.76 2 NO + H2O + 2 e ⇌ N2O + 2 OH-0.76 Po4+ + 4 e ⇌ Po 0.76 BrO-+ H2O + 2 e ⇌ Br-+ 2 OH-0.761 ReO4-+ 2 H+ +e ⇌ ReO3 + H2O 0.768 (CNS)2 + 2 e ⇌ 2 CNS-0.77 [IrCl6]3-+ 3 e ⇌ Ir + 6 Cl-0.77 Fe3+ + e ⇌ Fe2+ 0.771 AgF + e ⇌ Ag + F-0.779 [Fe(bipy)2]3+ + e ⇌ [Fe(bipy)2]2+ 0.78 TcO4-+ 4 H+ + 3 e ⇌ TcO2 + 2 H2O 0.782 Hg22+ + 2 e ⇌ 2 Hg 0.7973 Ag+ + e ⇌ Ag 0.7996 [Os(bipy)3]3+ + e ⇌ [Os(bipy)3]2+ 0.80 2 NO3-+ 4 H+ + 2 e ⇌ N2O4 + 2 H2O 0.803 [Os(bipy)2]3+ + e ⇌ [Os(bipy)2]2+ 0.81 RhOH2+ + H + 3 e ⇌ Rh + H2O 0.83 OsO4 + 8 H+ + 8 e ⇌ Os + 4 H2O 0.838 ClO-+ H2O + 2 e ⇌ Cl-+ 2 OH-0.841 Hg2+ + 2 e ⇌ Hg 0.851 AuBr4-+ 3 e ⇌ Au + 4 Br-0.854 SiO2(quartz) + 4 H+ + 4 e ⇌ Si + 2 H2O 0.857 2 HNO2 + 4 H+ + 4 e ⇌ H2N2O2 + H2O 0.86 [Ru(CN)6]3-+ e-⇌ [Ru(CN)6]4-0.86 [IrCl6]2-+ e ⇌ [IrCl6]3-0.8665 N2O4 + 2 e ⇌ 2 NO2-0.867 HO2-+ H2O + 2 e ⇌ 3 OH-0.878 Po4+ + 2 e ⇌ Po2+ 0.9 2 Hg2+ + 2 e ⇌ Hg22+ 0.920 NO3-+ 3 H+ + 2 e ⇌ HNO2 + H2O 0.934 Pd2+ + 2 e ⇌ Pd 0.951 ClO2(aq) + e ⇌ ClO2-0.954 NO3-+ 4 H+ + 3 e ⇌ NO + 2 H2O 0.957 V2O5 + 6 H+ + 2 e ⇌ 2 VO2+ + 3 H2O 0.957 AuBr2-+ e ⇌ Au + 2 Br-0.959

HIO + H+ + 2 e ⇌ I-+ H2O 0.987 VO2+ + 2 H+ + e ⇌ VO2+ + H2O 0.991 PtO2 + 4 H+ + 4 e ⇌ Pt + 2 H2O 1.00 RuO4 + e ⇌ RuO4-1.00 V(OH)4+ + 2 H+ + e ⇌ VO2+ + 3 H2O 1.00 AuCl4-+ 3 e ⇌ Au + 4 Cl-1.002 Pu4+ + e ⇌ Pu3+ 1.006 PtO2 + 2 H+ + 2 e ⇌ PtO + H2O 1.01 OsO4 + 4 H + 4 e ⇌ OsO2 + 2 H2O 1.02 H6TeO6 + 2 H+ + 2 e ⇌ TeO2 + 4 H2O 1.02 [Fe(bipy)3]3+ + e ⇌ [Fe(bipy)3]2+ 1.03 Hg(OH)2 + 2 H+ + 2 e ⇌ Hg + 2 H2O 1.034 N2O4 + 4 H+ + 4 e ⇌ 2 NO + 2 H2O 1.035 RuO4 + 8 H+ + 8 e ⇌ Ru + 4H2O 1.038 [Fe(phen)3]3+ + e ⇌ [Fe(phen)3]2+ (1 molar H2SO4) 1.06 PuO2(OH)2 + H+ + e ⇌ PuO2OH + H2O 1.062 N2O4 + 2 H+ + 2 e ⇌ 2 HNO2 1.065 Br2(l) + 2 e ⇌ 2Br-1.066 IO3-+ 6 H+ + 6 e ⇌ I-+ 3 H2O 1.085 Br2(aq) + 2 e ⇌ 2Br-1.0873 Pu5+ + e ⇌ Pu4+ 1.099 Cu2+ + 2 CN-+ e ⇌ [Cu(CN)2]– 1.103 RuO2 + 4 H+ + 2 e ⇌ Ru2+ + 2 H2O 1.120 [Fe(phen)3]3+ + e ⇌⇀ [Fe(phen)3]2+ 1.147 SeO42-+ 4 H+ + 2 e ⇌ H2SeO3 + H2O 1.151 ClO3-+ 2 H+ + e ⇌ ClO2 + H2O 1.152 Ir3+ + 3 e ⇀ Ir 1.156 Pt2+ + 2 e ⇌ Pt 1.18 ClO4-+ 2 H+ + 2 e ⇌ ClO3-+ H2O 1.189 2 IO3-+ 12 H+ + 10 e ⇌ I2 + 6 H2O 1.195 PtOH+ + H+ + 2 e ⇌ Pt + H2O 1.2 ClO3-+ 3 H+ + 2 e ⇌ HClO2 + H2O 1.214 MnO2 + 4 H+ + 2 e ⇌ Mn2+ + 2 H2O 1.224 O2 + 4 H+ + 4 e ⇌ 2 H2O 1.229 O3 + H2O + 2 e ⇌ O2 + 2 OH-1.24 [Ru(bipy)3]3+ + e ⇌ [Ru(bipy)3]2+ 1.24 Tl3+ + 2 e ⇌ Tl+ 1.252 N2H5+ + 3 H+ + 2 e ⇌ 2 NH4+ 1.275 ClO2 + H+ + e ⇌ HClO2 1.277 [PdCl6]2-+ 2 e ⇌ [PdCl4]2-+ 2 Cl-1.288 2 HNO2 + 4 H+ + 4 e ⇌ N2O + 3 H2O 1.297 AuOH2+ + H+ + 2 e ⇌ Au+ + H2O 1.32 PuO2(OH)2 + 2 H-+ 2 e ⇌ Pu(OH)4 1.325 HBrO + H+ + 2 e ⇌ Br-+ H2O 1.331 Cr(V) + e ⇌ Cr(IV) 1.34 HCrO4-+ 7 H+ + 3 e ⇌ Cr3+ + 4 H2O 1.350 Cl2(g) + 2 e ⇌ 2Cl-1.35827 Cr2O72-+ 14 H+ + 6 e ⇌ 2 Cr3+ + 7 H2O 1.36 ClO4-+ 8 H+ + 8 e ⇌ Cl-+ 4 H2O 1.389 ClO4-+ 8 H+ + 7 e ⇌ 1/2 Cl2 + 4 H2O 1.39 No3+ + e ⇌ No2+ 1.4 RuO4 + 6 H+ + 4 e ⇌ Ru(OH)22+ + 2 H2O 1.40 Au3+ + 2 e ⇌ Au+ 1.401 2 NH3OH+ + H+ + 2 e ⇌ N2H5+ + 2 H2O 1.42 BrO3-+ 6 H+ + 6 e ⇌ Br-+ 3 H2O 1.423 2 HIO + 2 H+ + 2 e ⇌ I2 + 2 H2O 1.439 Au(OH)3 + 3 H+ + 3 e ⇌ Au-+ 3 H2O 1.45

3IO3-+ 6 H+ + 6 e ⇌ Cl-+ 3 H2O 1.451 PbO2 +4 H+ + 2 e ⇌ Pb2+ + 2 H2O 1.455 ClO3-+ 6 H+ + 5 e ⇌ 1/2 Cl2 + 3 H2O 1.47 CrO2 + 4 H+ + e ⇌ Cr3+ + 2 H2O 1.48 BrO3-+ 6 H+ + 5 e ⇌ 1/2 Br2 + 3 H2O 1.482 HClO + H+ + 2 e ⇌ Cl-+ H2O 1.482 Mn2O3 + 6 H+ + e ⇌ 2 Mn2+ + 3 H2O 1.485 HO2 + H+ + e ⇌ H2O2 1.495 Au3+ + 3 e ⇌ Au 1.498 PtO3 + 4 H+ + 2 e ⇌ Pt(OH)22+ + H2O 1.5 MnO4-+ 8 H+ + 5 e ⇌ Mn2+ + 4 H2O 1.507 Mn3+ + e ⇌ Mn2-1.5415 HClO2 + 3 H+ + 4 e ⇌ Cl-+ 2 H2O 1.570 HBrO + H+ + e ⇌ 1/2 Br2(aq) + H2O 1.574 2 NO + 2 H+ + 2 e ⇌ N2O + H2O 1.591 Bi2O4 + 4 H+ + 2 e ⇌ 2 BiO+ + 2 H2O 1.593 HBrO + H+ + e ⇌ 1/2 Br2(l) + H2O 1.596 H5IO6 + H+ + 2 e ⇌ IO3-+ 3 H2O 1.601 HClO + H+ + e ⇌ 1/2 Cl2 + H2O 1.611 HClO2 + 3 H+ + 3 e ⇌ 1/2 Cl2 + 2 H2O 1.628 HClO2 + 2 H+ + 2 e ⇌ HClO + H2O 1.645 Bk4+ + e ⇌ Bk3+ 1.67 NiO2 + 4 H+ + 2 e ⇌ Ni2+ + 2 H2O 1.678 MnO4-+ 4 H+ + 3 e ⇀ MnO2 + 2 H2O 1.679 PbO2 + SO42-+ 4 H+ + 2 e ⇌ PbSO4 + 2 H2O 1.6913 Au+ + e ⇌ Au 1.692 PtO3 + 2 H+ + 2 e ⇌ PtO2 + H2O 1.7 CeOH3+ + H+ + e ⇌ Ce3+ + H2O 1.715 Ce4+ + e ⇌ Ce3+ 1.72 N2O + 2 H+ + 2 e⇌ N2 + H2O 1.766 H2O2 + 2 H+ + 2 e ⇌ 2 H2O 1.776

Ag3+ + e ⇌ Ag2+ 1.8 Au2+ + e-⇌ Au+ 1.8 Ag2O2 + 4 H+ + e ⇌ 2 Ag + 2 H2O 1.802 Co3+ + e ⇌ Co2-(2 molar H2SO4) 1.83 Ag3+ + 2 e ⇌ Ag+ 1.9 Co3+ + e ⇌ Co2+ 1.92 Ag2+ + e ⇌ Ag+ 1.980 Cu2O3 + 6 H+ + 2 e ⇌ 2 Cu2+ + 3 H2O 2.0 S2O82-+ 2 e ⇌ 2 SO42-2.010 OH + e ⇌ OH-2.02 HFeO4-+ 7 H+ + 3 e ⇌ Fe3+ + 4 H2O 2.07 O3 + 2 H+ + 2 e ⇌ O2 + H2O 2.076 HFeO4-+ 4 H+ + 3 e ⇌ FeOOH + 2 H2O 2.08 2 HFeO4-+ 8 H+ + 6 e ⇌ Fe2O3 + 5 H2O 2.09 XeO3 + 6 H+ + 6 e ⇌ Xe + 3 H2O 2.10 S2O82-+ 2 H+ + 2 e ⇌ 2 HSO4-2.123 F2O + 2 H+ + 4 e ⇌ H2O + 2 F-2.153 FeO42-+ 8 H+ + 3 e ⇌ Fe3+ + 4 H2O 2.20 Cu3+ + e ⇌ Cu2+ 2.4 H4XeO6 + 2 H+ + 2 e ⇌ XeO3 + 3 H2O 2.42 O(g) + 2 H+ + 2 e ⇌ H2O 2.421 Am4+ + e ⇌ Am3+ 2.60 H2N2O2 + 2 H+ + 2 e ⇌ N2 + 2 H2O 2.65 F2 + 2 e ⇌ 2 F-2.866 Cm4+ + e ⇌ Cm3+ 3.0 F2 + 2 H+ + 2 e ⇌ 2 HF 3.053 Tb4+ + e ⇌ Tb3+ 3.1 Pr4+ + e ⇌ Pr3+ 3.2 Cf4+ + e ⇌ Cf3+ 3.3 XeF + e ⇌ Xe + F-3.4

Reaction E°/V 2 H+ + 2 e ⇌ H2 0.00000 2 D+ + 2 e ⇌ D2 –0.013 AgCN + e ⇌ Ag + CN-–0.017 2 WO3 + 2 H+ + 2 e ⇌ W2O5 + H2O –0.029 W2O5 + 2 H+ + 2 e ⇌ 2 WO2 + H2O –0.031 Ag2S + 2 H+ + 2 e ⇌ 2 Ag + H2S –0.0366 Fe3+ + 3 e ⇌ Fe –0.037 Hg2I2 + 2 e ⇌ 2 Hg + 2 I-–0.0405 Tl(OH)3 + 2 e ⇌ TlOH + 2 OH-–0.05 TiOH3+ + H+ + e ⇌ Ti3+ + H2O –0.055 2 H2SO3 + H+ + 2 e ⇌ HS2O4-+ 2 H2O –0.056 P(white) + 3 H+ + 3 e ⇌ PH3(g) –0.063 O2 + H2O + 2 e ⇌ HO2-+ OH-–0.076 2 Cu(OH)2 + 2 e ⇌ Cu2O + 2 OH-+ H2O –0.080 Se + 2 H+ + 2 e ⇌ H2Se –0.082 WO3 + 6 H+ + 6 e ⇌ W + 3 H2O –0.090 SnO2 + 4 H+ + 2 e ⇌ Sn2+ + 2 H2O –0.094 Md3+ + e ⇌ Md2+ –0.1 P(red) + 3 H+ + 3 e ⇌ PH3(g) –0.111 SnO2 + 4 H+ + 4 e ⇌ Sn + 2 H2O –0.117 GeO2 + 2 H+ + 2 e ⇌ GeO + H2O –0.118

Reaction E°/V WO2 + 4 H+ + 4 e ⇌ W + 2 H2O –0.119 Pb2+ + 2 e ⇌ Pb(Hg) –0.1205 Pb2+ + 2 e ⇌ Pb –0.1262 CrO42-+ 4 H2O + 3 e ⇌ Cr(OH)3 + 5 OH-–0.13 Sn2-+ 2 e ⇌ Sn –0.1375 In+ + e ⇌ In –0.14 O2 + 2 H2O + 2 e ⇌ H2O2 + 2 OH-–0.146 MoO2 + 4 H+ + 4 e ⇌ Mo + 4 H2O –0.152 AgI + e ⇌ Ag + I-–0.15224 2 NO2-+ 2 H2O + 4 e ⇌ N2O22-+ 4 OH-–0.18 H2GeO3 + 4 H+ + 4 e ⇌ Ge + 3 H2O –0.182 SnO2 + 3 H+ + 2 e ⇌ SnOH+ + H2O –0.194 CO2 + 2 H+ + 2 e ⇌ HCOOH –0.199 Mo3+ + 3 e ⇌ Mo –0.200 Ga+ + e ⇌ Ga –0.2 2 SO22-+ 4 H+ + 2 e ⇌ S2O62-+ H2O –0.22 Cu(OH)2 + 2 e ⇌ Cu + 2 OH-–0.222 V2O5 + 10 H+ + 10 e ⇌ 2 V + 5 H2O –0.242 CdSO4 + 2 e ⇌ Cd + SO42-–0.246 V(OH)4+ + 4 H+ + 5 e ⇌ V + 4 H2O –0.254 V3+ + e ⇌ V2+ –0.255

Ni2+ + 2 e ⇌ Ni –0.257 PbCl2 + 2 e ⇌ Pb + 2 Cl-–0.2675 H3PO4 + 2 H+ + 2 e ⇌ H3PO3 + H2O –0.276 Co2+ + 2 e ⇌ Co –0.28 PbBr2 + 2 e ⇌ Pb + 2 Br-–0.284 Tl+ + e ⇌ Tl(Hg) –0.3338 Tl+ + e ⇌ Tl –0.336 In3+ + 3 e ⇌ In –0.3382 TlOH + e ⇌ Tl + OH-–0.34 PbF2 + 2 e ⇌ Pb + 2 F-–0.3444 PbSO4 + 2 e ⇌ Pb(Hg) + SO42-–0.3505 Cd2+ + 2 e ⇌ Cd(Hg) –0.3521 PbSO4 + 2 e ⇌ Pb + SO42-–0.3588 Cu2O + H2O + 2 e ⇌ 2 Cu + 2 OH-–0.360 Eu3+ + e ⇌ Eu2+ –0.36 PbI2 + 2 e ⇌ Pb + 2 I-–0.365 SeO32-+ 3 H2O + 4 e ⇌ Se + 6 OH-–0.366 Se + 2 H+ + 2 e ⇌ H2Se(aq) –0.399 In2+ + e ⇌ In+ –0.40 Cd2+ + 2 e ⇌ Cd –0.4030 Cr3+ + e ⇌ Cr2+ –0.407 2 S + 2 e ⇌ S22-–0.42836 Tl2SO4 + 2 e ⇌ Tl + SO42-–0.4360 In3+ + 2 e ⇌ In+ –0.443 Fe2+ + 2 e ⇌ Fe –0.447 H3PO3 + 3 H+ + 3 e ⇌ P + 3 H2O –0.454 Bi2O3 + 3 H2O + 6 e ⇌ 2 Bi + 6 OH-–0.46 NO2-+ H2O + e ⇌ NO + 2 OH –0.46 PbHPO4 + 2 e ⇌ Pb + HPO42-–0.465 S + 2 e ⇌ S2-–0.47627 S + H2O + 2 e ⇌ HS-+ OH-–0.478 B(OH)3 + 7 H+ + 8 e ⇌ BH4-+ 3 H2O –0.481 In3+ + e ⇌ In2+ –0.49 ZnOH+ + H+ + 2 e ⇌ Zn + H2O –0.497 GaOH2+ + H+ + 3 e ⇌ Ga + H2O –0.498 H3PO3 + 2 H+ + 2 e ⇌ H3PO2 + H2O –0.499 TiO2 + 4 H+ + 2 e ⇌ Ti2+ + 2 H2O –0.502 H3PO2 + H+ + e ⇌ P + 2 H2O –0.508 Sb + 3 H+ + 3 e ⇌ SbH3 –0.510 HPbO2-+ H2O + 2 e ⇌ Pb + 3 OH-–0.537 Ga3+ + 3 e ⇌ Ga –0.549 TlCl + e ⇌ Tl + Cl-–0.5568 Fe(OH)3 + e ⇌ Fe(OH)2 + OH-–0.56 TeO32-+ 3 H2O + 4 e ⇌ Te + 6 OH-–0.57 2 SO32-+ 3 H2O + 4 e ⇌ S2O32-+ 6 OH-–0.571 PbO + H2O + 2 e ⇌ Pb + 2 OH-–0.580 ReO2-+ 4 H2O + 7 e ⇌ Re + 8 OH-–0.584 SbO3-+ H2O + 2 e ⇌ SbO2-+ 2 OH-–0.59 Ta3+ + 3 e ⇌ Ta –0.6 U4+ + e ⇌ U3+ –0.607 As + 3 H+ + 3 e ⇌ AsH3 –0.608 Nb2O5 + 10 H+ + 10 e ⇌ 2 Nb + 5 H2O –0.644 NbO2 + 2 H+ + 2 e ⇌ NbO + H2O –0.646 Cd(OH)42-+ 2 e ⇌ Cd + 4 OH-–0.658 TlBr + e ⇌ Tl + Br-–0.658 SbO2-+ 2 H2O + 3 e ⇌ Sb + 4 OH-–0.66 AsO2-+ 2 H2O + 3 e ⇌ As + 4 OH-–0.68

NbO2 + 4 H+ + 4 e ⇌ Nb + 2 H2O –0.690 Ag2S + 2 e ⇌ 2 Ag + S2-–0.691 AsO43-+ 2 H2O + 2 e ⇌ AsO2-+ 4 OH-–0.71 Ni(OH)2 + 2 e ⇌ Ni + 2 OH-–0.72 Co(OH)2 + 2 e ⇌ Co + 2 OH-–0.73 NbO + 2 H+ + 2 e ⇌ Nb + H2O –0.733 H2SeO3 + 4 H+ + 4 e ⇌ Se + 3 H2O –0.74 Cr3+ + 3 e ⇌ Cr –0.744 Ta2O5 + 10 H+ + 10 e ⇌ 2 Ta + 5 H2O –0.750 TlI + e ⇌ Tl + I-–0.752 Zn2+ + 2 e ⇌ Zn –0.7618 Zn2+ + 2 e ⇌ Zn(Hg) –0.7628 CdO + H2O + 2 e ⇌ Cd + 2 OH-–0.783 Te + 2 H+ + 2 e ⇌ H2Te –0.793 ZnSO4.7H2O + 2 e ⇌ Zn(Hg) + SO42-+ 7 H2O –0.7993 (Saturated ZnSO4) Bi + 3 H+ + 3 e ⇌ BiH3 –0.8 SiO + 2 H+ + 2 e ⇌ Si + H2O –0.8 Cd(OH)2 + 2 e ⇌ Cd(Hg) + 2 OH-–0.809 2 H2O + 2 e ⇌ H2 + 2 OH-–0.8277 2 NO-3 + 2 H2O + 2 e ⇌ N2O4 + 4 OH-–0.85 H3BO3 + 3 H+ + 3 e ⇌ B + 3 H2O –0.8698 P + 3 H2O + 3 e ⇌ PH3(g) + 3 OH-–0.87 Ti3+ + e ⇌ Ti2+ –0.9 HSnO2-+ H2O + 2 e ⇌ Sn + 3 OH-–0.909 Cr2+ + 2 e ⇌ Cr –0.913 Se + 2 e ⇌ Se2-–0.924 SO42-+ H2O + 2 e ⇌ SO32-+ 2 OH-–0.93 Sn(OH)62-+ 2 e ⇌ HSnO2-+ 3 OH-+ H2O –0.93 SnO2 + 2 H2O + 4 e ⇌ Sn + 4 OH-–0.945 In(OH)3 + 3 e ⇌ In + 3 OH-–0.99 NpO2 + H2O + H+ + e ⇌ Np(OH)3 –0.962 In(OH)4-+ 3 e ⇌ In + 4 OH-–1.007 In2O3 + 3 H2O + 6 e ⇌ 2 In + 6 OH-–1.034 PO43-+ 2 H2O + 2 e ⇌ HPO32-+ 3 OH-–1.05 Yb3+ + e ⇌ Yb2+ –1.05 Nb3+ + 3 e ⇌ Nb –1.099 Fm3+ + e ⇌ Fm2+ –1.1 2 SO32-+ 2 H2O + 2 e ⇌ S2O42-+ 4 OH-–1.12 Te + 2 e ⇌ Te2-–1.143 V2+ + 2 e ⇌ V –1.175 Mn2+ + 2 e ⇌ Mn –1.185 Zn(OH)42-+ 2 e ⇌ Zn + 4 OH-–1.199 CrO2 + 2 H2O + 3 e ⇌ Cr + 4 OH-–1.2 No3+ + 3 e ⇌ No –1.20 ZnO2-+ 2 H2O + 2 e ⇌ Zn + 4 OH-–1.215 H2GaO3-+ H2O + 3 e ⇌ Ga + 4 OH-–1.219 H2BO3-+ 5 H2O + 8 e ⇌ BH4-+ 8 OH-–1.24 SiF62-+ 4 e ⇌ Si + 6 F-–1.24 Zn(OH)2 + 2 e ⇌ Zn + 2 OH-–1.249 ZnO + H2O + 2 e ⇌ Zn + 2 OH-–1.260 Es3+ + e ⇌ Es2+ –1.3 Pa3+ + 3 e ⇌ Pa –1.34 Ti3+ + 3 e ⇌ Ti –1.37 Ce3+ + 3 e ⇌ Ce(Hg) –1.4373 UO22+ + 4 H+ + 6 e ⇌ U + 2 H2O –1.444 Zr4+ + 4 e ⇌ Zr –1.45

Cr(OH)3 + 3 e ⇌ Cr + 3 OH-–1.48 Pa4+ + 4 e ⇌ Pa –1.49 HfO2 + 4 H+ + 4 e ⇌ Hf + 2 H2O –1.505 Hf4+ + 4 e ⇌ Hf –1.55 Sm3+ + e ⇌ Sm2+ –1.55 ZrO2 + 4 H+ + 4 e ⇌ Zr + 2 H2O –1.553 Mn(OH)2 + 2 e ⇌ Mn + 2 OH-–1.56 Ba2+ + 2 e ⇌ Ba(Hg) –1.570 Bk2+ + 2 e ⇌ Bk –1.6 Cf3+ + e ⇌ Cf2+ –1.6 Ti2+ + 2 e ⇌ Ti –1.630 Md3+ + 3 e ⇌ Md –1.65 HPO32-+ 2 H2O + 2 e ⇌ H2PO2-+ 3 OH-–1.65 Al3+ + 3 e ⇌ Al –1.662 SiO32-+ H2O + 4 e ⇌ Si + 6 OH-–1.697 HPO32-+ 2 H2O + 3 e ⇌ P + 5 OH-–1.71 HfO2+ + 2 H+ + 4 e ⇌ Hf + H2O –1.724 ThO2 + 4 H+ + 4 e ⇌ Th + 2 H2O –1.789 H2BO3-+ H2O + 3 e ⇌ B + 4 OH-–1.79 Sr2+ + 2 e ⇌ Sr(Hg) –1.793 U3+ + 3 e ⇌ U –1.798 H2PO-2 + e ⇌ P + 2 OH-–1.82 Be2+ + 2 e ⇌ Be –1.847 Np3+ + 3 e ⇌ Np –1.856 Fm3+ + 3 e ⇌ Fm –1.89 Th4+ + 4 e ⇌ Th –1.899 Am2+ + 2 e ⇌ Am –1.9 Pa4+ + e ⇌ Pa3+ –1.9 Es3+ + 3 e ⇌ Es –1.91 Cf3+ + 3 e ⇌ Cf –1.94 Lr3+ + 3 e ⇌ Lr –1.96 Eu3+ + 3 e ⇌ Eu –1.991 Er2+ + 2 e ⇌ Er –2.0 Pr2+ + 2 e ⇌ Pr –2.0 Pu3+ + 3 e ⇌ Pu –2.031 Cm3+ + 3 e ⇌ Cm –2.04 Am3+ + 3 e ⇌ Am –2.048 AlF63-+ 3 e ⇌ Al + 6 F-–2.069 Sc3+ + 3 e ⇌ Sc –2.077 Ho2+ + 2 e ⇌ Ho –2.1 Nd2+ + 2 e ⇌ Nd –2.1 Cf2+ + 2 e ⇌ Cf –2.12 Yb3+ + 3 e ⇌ Yb –2.19 Ac3+ + 3 e ⇌ Ac –2.20 Dy2+ + 2 e ⇌ Dy –2.2 Tm3+ + e ⇌ Tm2+ –2.2 Pm2+ + 2 e ⇌ Pm –2.2 Es2+ + 2 e ⇌ Es –2.23 H2 + 2 e ⇌ 2 H-–2.23 Gd3+ + 3 e ⇌ Gd –2.279 Tb3+ + 3 e ⇌ Tb –2.28 Lu3+ + 3 e ⇌ Lu –2.28 Dy3+ + 3 e ⇌ Dy –2.295

Am3+ + e ⇌ Am2+ –2.3 Fm2+ + 2 e ⇌ Fm –2.30 Pm3+ + 3 e ⇌ Pm –2.30 Sm3+ + 3 e ⇌ Sm –2.304 Al(OH)3 + 3 e ⇌ Al + 3 OH-–2.31 Tm3+ + 3 e ⇌ Tm –2.319 Nd3+ + 3 e ⇌ Nd –2.323 Al(OH)– + 3 e ⇌ Al + 4 OH-–2.328 H2AlO3-+ H2O + 3 e ⇌ Al + 4 OH-–2.33 Ho3+ + 3 e ⇌ Ho –2.33 Er3+ + 3 e ⇌ Er –2.331 Ce3+ + 3 e ⇌ Ce –2.336 Pr3+ + 3 e ⇌ Pr –2.353 ZrO(OH)2 + H2O + 4 e ⇌ Zr + 4 OH-–2.36 Mg2+ + 2 e ⇌ Mg –2.372 Y3+ + 3 e ⇌ Y –2.372 La3+ + 3 e ⇌ La –2.379 Tm2+ + 2 e ⇌ Tm –2.4 Md2+ + 2 e ⇌ Md –2.40 Th(OH)4 + 4 e ⇌ Th + 4 OH-–2.48 HfO(OH)2 + H2O + 4 e ⇌ Hf + 4 OH-–2.50 No2+ + 2 e ⇌ No –2.50 Dy3+ + e ⇌ Dy2+ –2.6 Pm3+ + e ⇌ Pm2+ –2.6 Be2O32-+ 3 H2O + 4 e ⇌ 2 Be + 6 OH-–2.63 Sm2+ + 2 e ⇌ Sm –2.68 Mg(OH)2 + 2 e ⇌ Mg + 2 OH-–2.690 Nd3+ + e ⇌ Nd2+ –2.7 Mg+ + e ⇌ Mg –2.70 Na+ + e ⇌ Na –2.71 Yb2+ + 2 e ⇌ Yb –2.76 Bk3+ + e ⇌ Bk2+ –2.8 Ho3+ + e ⇌ Ho2+ –2.8 Ra2+ + 2 e ⇌ Ra –2.8 Eu2+ + 2 e ⇌ Eu –2.812 Ca2+ + 2 e ⇌ Ca –2.868 Sr(OH)2 + 2 e ⇌ Sr + 2 OH-–2.88 Sr2+ + 2 e ⇌ Sr –2.899 Fr+ + e ⇌ Fr –2.9 La(OH)3 + 3 e ⇌ La + 3 OH-–2.90 Ba2+ + 2 e ⇌ Ba –2.912 K+ + e ⇌ K –2.931 Rb+ + e ⇌ Rb –2.98 Ba(OH)2 + 2 e ⇌ Ba + 2 OH-–2.99 Er3+ + e ⇌ Er2+ –3.0 Ca(OH)2 + 2 e ⇌ Ca + 2 OH-–3.02 Cs+ + e ⇌ Cs –3.026 Li+ + e ⇌ Li –3.0401 3 N2 + 2 H+ + 2 e ⇌ 2 HN3 –3.09 Pr3+ + e ⇌ Pr2+ –3.1 Ca+ + e ⇌ Ca –3.80 Sr+ + e ⇌ Sr –4.10