V_{Reduction}(H)=0 V_{Redox}(H)=4.44 eV V_{Redox}(A)=V_{Reduction}(A)+V_{Redox}(H)
| Species | VRedox(eV) |
|---|---|
| O2/O2- | 4.44-0.33 |
| O2/H2O | 4.44+1.229 |
| 0 | 0 |
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 | |
| 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 | |
| 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 | |
| Ba2+ + 2e− \rightleftharpoons Ba(s) | –2.91 |
| BaO(s) + 2H+ + 2e− \rightleftharpoons Ba(s) + H2O(l) | 2.365 |
| Beryllium | |
| Be2+ + 2e− \rightleftharpoons Be(s) | –1.99 |
| Bismuth | |
| Bi3+ + 3e− \rightleftharpoons Bi(s) | 0.317 |
| BiCl4− + 3e− \rightleftharpoons Bi(s) + 4Cl− | 0.199 |
| Boron | |
| B(OH)3 + 3H+ + 3e− \rightleftharpoons B(s) + 3H2O(l) | –0.890 |
| B(OH)4− + 3e− \rightleftharpoons B(s) + 4OH− | –1.811 |
| Bromine | |
| 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 | |
| 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 | |
| Ca2+ + 2e− \rightleftharpoons Ca(s) | –2.84 |
| Carbon | |
| 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 | |
| Ce3+ + 3e− \rightleftharpoons Ce(s) | –2.336 |
| Ce4+ + e− \rightleftharpoons Ce3+ | 1.44 |
| Cesium | |
| Cs+(aq) + e- \rightleftharpoons Css) | -2.92 |
| Chlorine | |
| Cl2(g) + 2e− \rightleftharpoons 2Cl− | 1.396 |
| ClO− + H2O(l) + e− \rightleftharpoons ½ Cl2(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 H ClO2 + 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 | |
| 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 2 Cr(OH)4− + 4OH− | –0.13 in 1 M NaOH |
| Cobalt | |
| 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 | |
| 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 | |
| F2(g) + 2H+ + 2e− \rightleftharpoons 2HF | 3.053 |
| F2(g) + 2e− \rightleftharpoons 2F− | 2.87 |
| Gallium | |
| Ga{3+} + 3e− \rightleftharpoons Ga(s) | -0.56 |
| Gold | |
| 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 | |
| 2H+ + 2e− \rightleftharpoons H_2(g) | 0.00000 |
| H2O + e− \rightleftharpoons \frac{1}{2}H2(g) + OH− | –0.828 |
| Iodine | |
| I2(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 | |
| 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 F e(phen)62+ | 1.147 |
| Lanthanum | |
| La3+ + 3e− \rightleftharpoons La(s) | –2.38 |
| Lead | |
| 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 | |
| Li+ + e− \rightleftharpoons Li(s) | –3.040 |
| Magnesium | |
| Mg2+ + 2e− \rightleftharpoons Mg(s) | –2.356 |
| Mg(OH)2(s) + 2e− \rightleftharpoons Mg(s) + 2OH− | –2.687 |
| Manganese | |
| 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 | |
| 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 | |
| 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 | |
| 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 | |
| N2(g) + 5H+ + 4e− \rightleftharpoons N2H5+ | –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 |
| NO2(g) + H+(aq) + e- \rightleftharpoons HNO2(aq) | 1.07 |
| NO3-(aq) + 4H+(aq) + 3e- \rightleftharpoons NO(g) + 2H2O(l) | 0.96 |
| Oxygen | |
| O2(g) + 2H+ + 2e− \rightleftharpoons H2O2 | 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 | |
| P(s,white) + 3H+ + 3e− \rightleftharpoons PH3(g) | 0.06 |
| H3PO3+ 2H+ + 2e− \rightleftharpoons H3PO2 + H2O(l) | -0.50 |
| H3PO4 + 2H+ + 2e− \rightleftharpoons H3PO3 + H2O(l) | -0.28 |
| Platinum | |
| Pt2+ + 2e− \rightleftharpoons Pt(s) | 1.2 |
| PtCl42− + 2e− \rightleftharpoons Pt(s) + 4Cl− | 0.73 |
| PtCl62− + 2e− \rightleftharpoons PtCl42- + 2Cl− | 0.68 |
| Potassium | |
| K+ + e− \rightleftharpoons K(s) | -2.93 |
| Rubidium | | |
| Rb+ + e- \rightleftharpoons Rb (s) | -2.98 |
| Ruthenium | |
| 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 | |
| Se(s) + 2e−\rightleftharpoons Se2- | –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 | |
| SiF_62- + 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 | |
| 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 | |
| Na+ + e- \rightleftharpoons Na(s) | –2.713 |
| Strontium | |
| Sr2+ + 2e- \rightleftharpoons Sr(s) | –2.89 |
| Sulfur | |
| S(s) + 2e- \rightleftharpoons S2- | –0.407 |
| S(s) + 2H+ + 2e− \rightleftharpoons H2S | 0.144 |
| S2O62− + 4H+ + 2e− \rightleftharpoons 2H2SO 3 | 0.569 |
| S2O82− + 2e− \rightleftharpoons 2SO4^2 −^ | 1.96 |
| S4O62− + 2e− \rightleftharpoons 2S2O~3 ~2− | 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 | |
| Tl^{3+} + 2e- \rightleftharpoons Tl+ | 0.77 in 1 M HCl |
| Tl3+ + 3e− \rightleftharpoons Tl(s) | 0.742 |
| Tin | |
| Sn2+ + 2e− \rightleftharpoons Sn(s) | -0.14 |
| Sn4+ + 2e− \rightleftharpoons Sn2+ | 0.154 |
| Titanium | |
| Ti2+ + 2e- \rightleftharpoons Ti(s) | –0.163 |
| Ti3+ + e− \rightleftharpoons Ti2+ | –0.37 |
| Tungsten | |
| WO2 (s) + 4H+ + 4e- \rightleftharpoons W(s) + 2H2O(l) | –0.119 |
| WO3(s) + 6H+ + 6e− \rightleftharpoons W(s) + 3H2O(l) | –0.090 |
| Uranium | |
| U3+ + 3e− \rightleftharpoons U(s) | –1.66 |
| U4+ + e− \rightleftharpoons U3+ | –0.52 |
| UO2+ + 4H+ + e− \rightleftharpoons U^ 4+^ + 2H2O(l) | 0.27 |
| UO22+ + e− \rightleftharpoons UO 2+ | 0.16 |
| UO22+ + 4H+ + 2e− \rightleftharpoons U4+ + 2H2O(l) | 0.327 |
| Vanadium | |
| V2++2e-\rightleftharpoonsV(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 | |
| 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 |