Appendix: Standard Reduction Potentials by Value | Introductory Chemistry

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⁻⇌ PtCl₄^2- + 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
Cr₂O₇^2-(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.