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Reference Tables and Other Information for Chemistry
Standard Reduction Potential Values
Standard reduction potential values for a variety of half cells are shown in the table below. Values are expressed in volts relative to the standard hydrogen electrode (SHE). Values assume gas pressures of 1.00 atm, solute concentrations of 1.00 M, and a temperature of 25°C. Learn more on our Tutorial page.
| Cathode (Reduction) Half-Reaction |
Standard Potential
E° (volts) |
| Li+(aq) + e- → Li(s) |
-3.04 |
| K+(aq) + e- → K(s) |
-2.92 |
| Ca2+(aq) + 2e- → Ca(s) |
-2.76 |
| Na+(aq) + e- → Na(s) |
-2.71 |
| Mg2+(aq) + 2e- → Mg(s) |
-2.38 |
| Al3+(aq) + 3e- → Al(s) |
-1.66 |
| 2H2O(l) + 2e- → H2(g) + 2OH-(aq) |
-0.83 |
| Zn2+(aq) + 2e- → Zn(s) |
-0.76 |
| Cr3+(aq) + 3e- → Cr(s) |
-0.74 |
| Fe2+(aq) + 2e- → Fe(s) |
-0.41 |
| Cd2+(aq) + 2e- → Cd(s) |
-0.40 |
| Ni2+(aq) + 2e- → Ni(s) |
-0.23 |
| Sn2+(aq) + 2e- → Sn(s) |
-0.14 |
| Pb2+(aq) + 2e- → Pb(s) |
-0.13 |
| Fe3+(aq) + 3e- → Fe(s) |
-0.04 |
| 2H+(aq) + 2e- → H2(g) |
0.00 |
| Sn4+(aq) + 2e- → Sn2+(aq) |
0.15 |
| Cu2+(aq) + e- → Cu+(aq) |
0.16 |
| ClO4-(aq) + H2O(l) + 2e- → ClO3-(aq) + 2OH-(aq) |
0.17 |
| AgCl(s) + e- → Ag(s) + Cl-(aq) |
0.22 |
| Cu2+(aq) + 2e- → Cu(s) |
0.34 |
| ClO3-(aq) + H2O(l) + 2e- → ClO2-(aq) + 2OH-(aq) |
0.35 |
| IO-(aq) + H2O(l) + 2e- → I-(aq) + 2OH-(aq) |
0.49 |
| Cu+(aq) + e- → Cu(s) |
0.52 |
| I2(s) + 2e- → 2I-(aq) |
0.54 |
| ClO2-(aq) + H2O(l) + 2e- → ClO-(aq) + 2OH-(aq) |
0.59 |
| Fe3+(aq) + e- → Fe2+(aq) |
0.77 |
| Hg22+(aq) + 2e- → 2Hg(l) |
0.80 |
| Ag+(aq) + e- → Ag(s) |
0.80 |
| Hg2+(aq) + 2e- → Hg(l) |
0.85 |
| ClO-(aq) + H2O(l) + 2e- → Cl-(aq) + 2OH-(aq) |
0.90 |
| 2Hg2+(aq) + 2e- → Hg22+(aq) |
0.90 |
| NO3-(aq) + 4H+(aq) + 3e- → NO(g) + 2H2O(l) |
0.96 |
| Br2(l) + 2e- → 2Br-(aq) |
1.07 |
| O2(g) + 4H+(aq) + 4e- -→ 2H2O(l) |
1.23 |
| Cr2O72-(aq) + 14H+(aq) + 6e- → 2Cr3+(aq) + 7H2O(l) |
1.33 |
| Cl2(g) + 2e- → 2Cl-(aq) |
1.36 |
| Ce4+(aq) + e- → Ce3+(aq) |
1.44 |
| MnO4-(aq) + 8H+(aq) + 5e- → Mn2+(aq) + 4H2O(l) |
1.49 |
| H2O2(aq) + 2H+(aq) + 2e- → 2H2O(l) |
1.78 |
| Co3+(aq) + e- → Co2+(aq) |
1.82 |
| S2O82-(aq) + 2e- → 2SO42-(aq) |
2.01 |
| O3(g) + 2H+(aq) + 2e- → O2(g) + H2O(l) |
2.07 |
| F2(g) + 2e- → 2F-(aq) |
2.87 |
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