Appendix E: Standard Reduction Potentials by Value
Standard Cathode (Reduction) Half-Reaction | Standard Reduction Potential E° (volts) |
---|---|
Li+(aq) + e– ⇌ Li(s) |
–3.040 |
Ba2+ + 2e−⇌ Ba(s) |
–2.92 |
Rb+ + e– ⇌ Rb (s) |
-2.98 |
K+(aq) + e– ⇌ K(s) |
-2.93 |
Cs+(aq) + e– ⇌ Cs(s) |
-2.92 |
Ba2+(aq) + 2e- ⇌ Ba(s) |
-2.91 |
Sr2+(aq) + 2e- ⇌ Sr(s) |
-2.89 |
Ca2+(aq) + 2e- ⇌ Ca(s) |
–2.84 |
Na+(aq) + e– ⇌ Na(s) |
–2.713 |
Mg(OH)2(s) + 2e−⇌ Mg(s) + 2OH− |
–2.687 |
La3+ + 3e−⇌ La(s) |
–2.38 |
Mg2+(aq) + 2e– ⇌ Mn(s) |
-2.356 |
Ce3+ + 3e−⇌ Ce(s) |
–2.336 |
Al(OH)4− + 3e−⇌ Al(s) + 4OH− |
–2.310 |
AlF63− + 3e−⇌ Al(s) + 6F− |
–2.07 |
Be2+ + 2e−⇌ Be(s) |
–1.99 |
B(OH)4− + 3e−⇌ B(s) + 4OH− |
–1.811 |
U3+ + 3e−⇌ U(s) |
–1.66 |
Al3+(aq) + 3e– ⇌ Al(s) |
–1.676 |
SiF62− + 4e−⇌ Si(s) + 6F− |
–1.37 |
Zn(CN)42− + 2e−⇌ Zn(s) + 4CN |
–1.34 |
Zn(OH)42− + 2e−⇌ Zn(s) + 4OH− |
–1.285 |
Mn2+ + 2e−⇌ Mn(s) |
–1.17 |
V2+ + 2e−⇌ V(s) |
–1.13 |
2SO32− + 2H2O(l) + 2e− ⇌ S2O42− + 4OH− |
–1.13 |
Zn(NH3)42+ + 2e− ⇌ Zn(s) + 4NH3 |
–1.04 |
O2 (aq) + e– ⇌ O2–(aq) |
-1.0 |
Cd(CN)42− + 2e−⇌ Cd(s) + 4CN− |
–0.943 |
MoO42− + 4H2O(l) + 6e−⇌Mo(s) + 8OH− |
–0.913 |
SiO2(s) + 4H+ + 4e−⇌ Si(s) + 2H2O(l) |
–0.909 |
SO42− + H2O(l) + 2e− ⇌ SO32−+ 2OH− |
–0.936 |
Cr2+ + 2e− ⇌ Cr(s) |
–0.90 |
B(OH)3 + 3H+ + 3e− ⇌ B(s) + 3H2O(l) |
–0.890 |
2H2O(l) + 2e– ⇌ H2(g) + 2OH–(aq) |
-0.828 |
Zn2+(aq) + 2e– ⇌ Zn(s) |
–0.7618 |
Co(OH)2(s) + 2e−⇌ Co(s) + 2OH− |
–0.746 |
Cr3+(aq) + 3e– ⇌ Cr(s) |
–0.424 |
Ni(OH)2 + 2e−⇌ Ni(s) + 2OH− |
–0.72 |
Ag2S(s) + 2e−⇌ 2Ag(s) + S2− |
–0.71 |
Se(s) + 2e−⇌ Se2− |
–0.67 in 1 M NaOH |
Cd(NH3)42+ + 2e−⇌ Cd(s) + 4NH3 |
–0.622 |
2SO32− + 3H2O(l) + 4e− ⇌S2O32− + 6OH− |
–0.576 in 1 M NaOH |
U4+ + e− ⇌ U3+ |
–0.52 |
SiO2(s) + 8H+ + 8e− ⇌ SiH4(g) + 2H2O(l) |
–0.516 |
Sb + 3H+ + 3e− ⇌ SbH3(g) |
–0.510 |
H3PO3+ 2H+ + 2e− ⇌ H3PO2 + H2O(l) |
-0.50 |
Ni(NH3)62+ + 2e− ⇌ Ni(s) + 6NH3 |
–0.49 |
2CO2(g) + 2H+ +2e−⇌ H2C2O4 |
–0.481 |
Cr3+ + e−⇌ Cr2+ |
–0.424 |
Fe2+(aq) + 2e– ⇌ Fe(s) |
-0.44 |
S(s) + 2e−⇌ S2− |
–0.407 |
Cd2+(aq) + 2e– ⇌ Cd(s) |
–0.4030 |
Ag(NH3)2+ + e−⇌ Ag(s) + 2NH3 |
–0.373 |
Ti3+ + e−⇌ Ti2+ |
–0.37 |
PbSO4(s) + 2e−⇌ Pb(s) + SO42− |
–0.356 |
Co2+(aq) + 2e– ⇌ Co(s) |
–0.277 |
2SO42− + 4H+ + 2e− ⇌ S2O62− + 2H2O(l) |
–0.25 |
N2(g) + 5H+ + 4e−⇌ N2H5+ |
–0.23 |
H3PO4 + 2H+ + 2e−⇌ H3PO3 + H2O(l) |
-0.28 |
Ni2+(aq) + 2e– ⇌ Ni(s) |
–0.257 |
V3+ + e− ⇌ V2+ |
–0.255 |
As + 3H+ + 3e− ⇌ AsH3(g) |
–0.225 |
CO2(g) + 2H+ + 2e− ⇌ HCO2H |
–0.20 |
Mo3+ + 3e− ⇌ Mo(s) |
–0.2 |
Sn2+ + 2e− ⇌ Sn(s) |
–0.19 in 1 M HCl |
Ti2+ + 2e−⇌ Ti(s) |
–0.163 |
MoO2(s) + 4H+ + 4e−⇌ Mo(s) + 2H2O(l) |
–0.152 |
AgI(s) + e− ⇌ Ag(s) + I− |
–0.152 |
Sn2+(aq) + 2e– ⇌ Sn(s) |
-0.14 |
Pb2+(aq) + 2e– ⇌ Pb(s) |
-0.126 |
CrO42− + 4H2O(l) + 3e− ⇌2Cr(OH)4− + 4OH− |
–0.13 in 1 M NaOH |
WO2(s) + 4H+ + 4e−⇌ W(s) + 2H2O(l) |
–0.119 |
Se(s) + 2H+ + 2e−⇌ H2Se(g) |
–0.115 |
CO2(g) + 2H+ + 2e−⇌ CO(g) + H2O(l) |
–0.106 |
WO3(s) + 6H+ + 6e−⇌ W(s) + 3H2O(l) |
–0.090 |
Hg2I2(s) + 2e−⇌ 2Hg(l) + 2I− |
–0.0405 |
Fe3+(aq) + 3e– ⇌ Fe(s) |
-0.037 |
2H+(aq) + 2e– ⇌ H2(g) |
0.00 |
P(s,white) + 3H+ + 3e−⇌ PH3(g) |
0.06 |
AgBr(s) + e−⇌ Ag(s) + Br− |
0.071 |
S4O62− + 2e−⇌2S2O32− |
0.080 |
Co(NH3)63+ +e−⇌Co(NH3)62+ |
0.1 |
Ru(NH3)63+ + e−⇌ Ru(s) + Ru(NH3)62+ |
0.10 |
S(s) + 2H+ + 2e−⇌ H2S |
0.144 |
Sn4+(aq) + 2e– ⇌ Sn2+(aq) |
0.154 |
Cu2+(aq) + e– ⇌ Cu+(aq) |
0.159 |
UO22+ + e− ⇌UO2+ |
0.16 |
Co(OH)3(s) + e−⇌ Co(OH)2(s) + OH− |
0.17 |
ClO4–(aq) + H2O(l) + 2e- ⇌ ClO3–(aq) + 2OH–(aq) |
0.17 |
SO42− + 4H+ + 2e− ⇌ H2SO32−+ H2O(l) |
0.172 |
BiCl4− + 3e−⇌ Bi(s) + 4Cl− |
0.199 |
SbO+ + 2H+ + 3e−⇌ Sb(s) + H2O(l) |
0.212 |
AgCl(s) + e– ⇌ Ag(s) + Cl–(aq) |
0.2223 |
HCHO + 2H+ + 2e−⇌ CH3OH |
0.2323 |
HAsO2 + 3H+ + 3e−⇌ As(s) + 2H2O(l) |
0.240 |
Ru3+ + e−⇌ Ru2+ |
0.249 |
IO3−+ 3H2O(l) + 6e−⇌ I− + 6OH− |
0.257 |
Hg2Cl2(s) + 2e−⇌ 2Hg(l) + 2Cl− |
0.2682 |
UO2+ + 4H+ + e− ⇌U4+ + 2H2O(l) |
0.27 |
Bi3+ + 3e−⇌ Bi(s) |
0.317 |
UO22+ + 4H+ + 2e− ⇌ U4+ + 2H2O(l) |
0.327 |
VO2+ + 2H+ +e−⇌V3+ + H2O(l) |
0.337 |
Cu2+(aq) + 2e– ⇌ Cu(s) |
0.3419 |
ClO3–(aq) + H2O(l) + 2e– ⇌ ClO2–(aq) + 2OH–(aq) |
0.35 |
Fe(CN)63− + e− ⇌ Fe(CN)64− |
0.356 |
O2(g) + 2H2O(l) + 4e−⇌ 4OH− |
0.401 |
ClO− + H2O(l) + e− ⇌ ½Cl2(g) + 2OH− |
0.421 in 1 M NaOH |
Ag2C2O4(s) + 2e−⇌ 2Ag(s) + C2O42− |
0.47 |
Cu+(aq) + e– ⇌ Cu(s) |
0.52 |
I2(s) + 2e– ⇌ 2I–(aq) |
0.5355 |
I3− + 2e−⇌ 3I− |
0.536 |
Ga3+ + 3e−⇌ Ga(s) |
-0.56 |
Cu2+ + Cl− + e−⇌ CuCl(s) |
0.559 |
S2O62− + 4H+ + 2e−⇌ 2H2SO3 |
0.569 |
H3AsO4 + 2H+ + 2e−⇌ HAsO2 + 2H2O(l) |
0.560 |
ClO2–(aq) + H2O(l) + 2e– ⇌ ClO–(aq) + 2OH–(aq) |
0.59 |
MnO4− + 2H2O(l) + 3e−⇌ MnO2(s) + 4OH− |
0.60 |
Sb2O5(s) + 6H+ + 4e−⇌ 2SbO+ + 3H2O(l) |
0.605 |
PtCl62− + 2e−⇌ PtCl42- + 2Cl− |
0.68 |
RuO2(s) + 4H+ + 4e−⇌ Ru(s) + 2H2O(l) |
0.68 |
O2(g) + 2H+ + 2e−⇌ H2O2 |
0.695 |
PtCl42− + 2e−⇌ Pt(s) + 4Cl− |
0.73 |
H2SeO3 + 4H+ + 4e−⇌ Se(s) + 3H2O(l) |
0.74 |
Tl3+ + 3e−⇌ Tl(s) |
0.742 |
Fe3+(aq) + e– ⇌ Fe2+(aq) |
0.771 |
Hg22+(aq) + 2e– ⇌ 2Hg(l) |
0.7960 |
Ag+(aq) + e- ⇌ Ag(s) |
0.7996 |
Hg2+(aq) + 2e– ⇌ Hg(l) |
0.8535 |
Cu2+ + I− +e−⇌ CuI(s) |
0.86 |
Ru(CN)63− +e−⇌ Ru(s) + Ru(CN)64− |
0.86 |
ClO− + H2O(l) + 2e−⇌ Cl− + 2OH− |
0.890 in 1 M NaOH |
2Hg2+(aq) + 2e– ⇌ Hg22+(aq) |
0.911 |
HgO(s) + 2H+ + 2e−⇌ Hg(l) + H2O(l) |
0.926 |
NO3− + 3H+ + 2e−⇌ HNO2 + H2O(l) |
0.94 |
MnO2(s) + 4H+ + e– ⇌ Mn3+ (aq) + H2O(I) |
0.95 |
NO3–(aq) + 4H+(aq) + 3e– ⇌ NO(g) + 2H2O(l) |
0.96 |
HIO + H+ + 2e−⇌ I− + H2O(l) |
0.985 |
HNO2 + H+ +e−⇌ NO(g) + H2O(l) |
0.996 |
VO22+ + 2H+ +e−⇌ VO2+ + H2O(l) |
1.000 |
AuCl4− + 3e−⇌ Au(s) + 4Cl− |
1.002 |
NO2 (g) + H+ (aq) + e– ⇌ HNO2 (aq) |
1.07 |
Br2(l) + 2e– ⇌ 2Br–(aq) |
1.087 |
Fe(phen)63+ +e− ⇌ Fe(phen)62+ |
1.147 |
SeO43− + 4H+ + e−⇌ H2SeO3 + H2O(l) |
1.151 |
ClO3− + 2H+ + e−⇌ ClO2(g) + H2O |
1.175 |
ClO3− + 3H+ + 2e− ⇌ HClO2 + H2O |
1.181 |
IO3− + 6H+ + 5e−⇌ ½I2(s) + 3H2O(l) |
1.195 |
Pt2+ + 2e−⇌ Pt(s) |
1.2 |
ClO4− + 2H+ + 2e− ⇌ ClO3− + H2O |
1.201 |
O2(g) + 4H+(aq) + 4e– ⇌ 2H2O(l) |
1.229 |
MnO2(s) + 4H+ + 2e−⇌ Mn2+ + 2H2O(l) |
1.23 |
Tl3+ + 2e− ⇌ Tl+ |
0.77 in 1 M HCl |
2HNO2 + 4H+ + 4e−⇌ N2O(g) + 3H2O(l) |
1.297 |
HOBr + H+ + 2e−⇌ Br− + H2O(l) |
1.341 |
Cr2O72-(aq) + 14H+(aq) + 6e– ⇌ 2Cr3+(aq) + 7H2O(l) |
1.36 |
Cr2O72− + 14H+ + 6e− ⇌ 2Cr3+ + 7H2O(l) |
1.36 |
Cl2(g) + 2e– ⇌ 2Cl–(aq) |
1.396 |
Au3+ + 2e−⇌ Au+ |
1.36 |
Hg2Br2(s) + 2e−⇌ 2Hg(l) + 2Br− |
1.392 |
Ce4+(aq) + e– ⇌ Ce3+(aq) |
1.44 |
PbO2(s) + 4H+ +2e– ⇌ Pb2+(aq) + 2H2O(l) |
1.46 |
BrO3− + 6H+ + 6e−⇌ Br− + 3H2O |
1.478 |
Mn3+ + e−⇌ Mn2+ |
1.5 |
MnO4–(aq) + 8H+(aq) + 5e– ⇌ Mn2+(aq) + 4H2O(l) |
1.51 |
BrO3− + 6H+ + 5e−⇌ ½Br2(l) + 3H2O |
1.5 |
Au3+ + 3e−⇌ Au(s) |
1.52 |
2NO(g) + 2H+ + 2e−⇌ N2O(g) + H2O(l) |
1.59 |
HOBr + H+ + e−⇌ ½Br− + H2O(l) |
1.604 |
HClO2 + 2H+ + 2e−⇌ HOCl + H2O |
1.64 |
PbO2(s) + 4SO42− + 4H+ + 2e−⇌ PbSO4(s) + 2H2O(l) |
1.690 |
MnO4− + 4H+ +3e−⇌ MnO2(s) + 2H2O(l) |
1.70 |
Ce4+ + e−⇌ Ce3+ |
1.72 |
N2O(g) + 2H+ + 2e−⇌ N2(g) + H2O(l) |
1.77 |
H2O2(aq) + 2H+(aq) + 2e– ⇌ 2H2O(l) |
1.763 |
Au+ + e−⇌ Au(s) |
1.83 |
Co3+(aq) + e− ⇌ Co2+(aq) |
1.92 |
S2O82− + 2e−⇌2SO42− |
1.96 |
O3(g) + 2H+(aq) + 2e− ⇌ O2(g) + H2O(l) |
2.07 |
BaO(s) + 2H+ + 2e−⇌ Ba(s) + H2O(l) |
2.365 |
F2(g) + 2e− ⇌ 2F−(aq) |
2.87 |
F2(g) + 2H+ + 2e−⇌ 2HF |
3.053 |
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Original source materials: 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.