10.13: Standard Reduction Potentials

The following table provides E^o and E^o ́ values for selected reduction reactions. Values are from the following sources (primarily the first two):

• 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.
• Bratsch, S. G. "Standard Electrode Potentials and Temperature Coefficients in Water at 298.15K, J. Phys. Chem. Ref. Data, 1989, 18, 1–21.
• Latimer, W. M. Oxidation Potentials, 2nd. Ed., Prentice-Hall: Englewood Cliffs, NJ, 1952

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 (E^o ́) are listed next to the potential.

For most of the reduction half-reactions gathered here, there are minor differences in values provided by the references above. In most cases, these differences are small and will not affect calculations. In a few cases the differences are not insignificant and the user may find discrepancies in calculations. For example, Bard, Parsons, and Jordon report an E^o value of –1.285 V for

$$\text{Zn(OH)}_4^{2-} + 2e^- \rightleftharpoons \text{Zn}(s) + 4\text{OH}^-\nonumber$$

while Milazzo, Caroli, and Sharma report the value as –1.214 V, Swift reports the value as –1.22, Bratsch reports the value as –1.199 V, and Latimer reports the value as –1.216 V.

Aluminum	E (V)	E^o ́ (V)
$\text{Al}^{3+} + 3e^- \rightleftharpoons \text{Al}(s)$	–1.676
$\text{Al(OH)}_4^- + 3e^- \rightleftharpoons \text{Al}(s) + 4\text{OH}^-$	–2.310
$\text{AlF}_6^{3-} + 3e^- \rightleftharpoons \text{Al}(s) + 6\text{F}^-$	–2.07

Antimony	E (V)	E^o ́ (V)
$\text{Sb} + 3\text{H}^+ + 3e^- \rightleftharpoons \text{SbH}_3(g)$	–0.510
$\text{Sb}_2\text{O}_5 + 6\text{H}^+ + 4e^- \rightleftharpoons 2\text{SbO}^+ + 3\text{H}_2\text{O}(l)$	0.605
$\text{SbO}^+ + 2\text{H}^+ + 3e^- \rightleftharpoons \text{Sb}(s) + \text{H}_2\text{O}(l)$	0.212

Arsenic	E (V)	E^o ́ (V)
$\text{As}(s) + 3\text{H}^+ + 3e^- \rightleftharpoons \text{AsH}_3(g)$	–0.225
$\text{H}_3\text{AsO}_4 + 2\text{H}^+ + 2e^- \rightleftharpoons \text{HAsO}_2 + 2\text{H}_2\text{O}(l)$	0.560
$\text{HAsO}_2 + 3\text{H}^+ + 3e^- \rightleftharpoons \text{As}(s) + 2\text{H}_2\text{O}(l)$	0.240

Barium	E (V)	E^o ́ (V)
$\text{Ba}^{2+} + 2e^- \rightleftharpoons \text{Ba}(s)$	–2.92
$\text{BaO}(s) + 2\text{H}^+ + 2e^- \rightleftharpoons \text{Ba}(s) + \text{H}_2\text{O}(l)$	–2.166

 

Beryllium	E (V)	E^o ́ (V)
$\text{Be}^{2+} + 2e^- \rightleftharpoons \text{Be}(s)$	–1.99

Bismuth	E (V)	E^o ́ (V)
$\text{Bi}^{3+} + 3e^- \rightleftharpoons \text{Bi}(s)$	0.317
$\text{BiCl}_4^- + 3e^- \rightleftharpoons \text{Bi}(s) + 4\text{Cl}^-$	0.199

Boron	E (V)	E^o ́ (V)
$\text{B(OH)}_3 + 3\text{H}^+ + 3e^- \rightleftharpoons \text{B}(s) + 3\text{H}_2\text{O}(l)$	–0.890
$\text{B(OH)}_4^- + 3e^- \rightleftharpoons \text{B}(s) + 4\text{OH}^-$	–1.811

Bromine	E (V)	E^o ́ (V)
$\text{Br}_2(l) + 2e^- \rightleftharpoons 2\text{Br}^-$	1.087
$\text{HOBr} + \text{H}^+ + 2e^- \rightleftharpoons \text{Br}^- + \text{H}_2\text{O}(l)$	1.341
$\text{HOBr} + \text{H}^+ + e^- \rightleftharpoons \frac{1}{2} \text{Br}_2 + \text{H}_2\text{O}(l)$	1.604
$\text{BrO}^- + \text{H}_2\text{O}(l) + 2e^- \rightleftharpoons \text{Br}^- + 2\text{OH}^-$		0.76 in 1 M NaOH
$\text{BrO}_3^- +6\text{H}^+ + 5e^- \rightleftharpoons \frac{1}{2} \text{Br}_2(l) + 3\text{H}_2\text{O}(l)$	1.5
$\text{BrO}_3^- + 6\text{H}^+ +6e^- \rightleftharpoons \text{Br}^- + 3\text{H}_2\text{O}(l)$	1.478

Cadmium	E (V)	E^o ́ (V)
$\text{Cd}^{2+} + 2e^- \rightleftharpoons \text{Cd}(s)$	–0.4030
$\text{Cd(CN)}_4^{2-} + 2e^- \rightleftharpoons \text{Cd}(s) + 4\text{CN}^-$	–0.943
$\text{Cd(NH}_3)_4^{2+} + 2e^- \rightleftharpoons \text{Cd}(s) + 4\text{NH}_3$	–0.622

Calcium	E (V)	E^o ́ (V)
$\text{Ca}^{2+} + 2e^- \rightleftharpoons \text{Ca}(s)$	–2.84

Carbon	E (V)	E^o ́ (V)
$\text{CO}_2(g) + 2\text{H}^+ + 2e^- \rightleftharpoons \text{CO}(g) + \text{H}_2\text{O}(l)$	–0.106
$\text{CO}_2(g) + 2\text{H}^+ +2e^- \rightleftharpoons \text{HCO}_2\text{H}$	–0.20
$2\text{CO}_2(g) + 2\text{H}^+ +2e^- \rightleftharpoons \text{H}_2\text{C}_2\text{O}_4$	–0.481
$\text{HCHO} + 2\text{H}^+ + 2e^- \rightleftharpoons \text{CH}_3\text{OH}$	0.2323

Cerium	E (V)	E^o ́ (V)
$\text{Ce}^{3+} + 3e^- \rightleftharpoons \text{Ce}(s)$	–2.336
$\text{Ce}^{4+} + e^- \rightleftharpoons \text{Ce}^{3+}$	1.72	1.70 in 1 M HClO4 1.44 in 1 M H2SO4 1.61 in 1 M HNO3 1.28 in 1 M HCl

Chlorine	E (V)	E^o ́ (V)
$\text{Cl}_2(g) + 2e^- \rightleftharpoons 2\text{Cl}^-$	1.396
$\text{ClO}^- + \text{H}_2\text{O}(l) + e^- \rightleftharpoons \frac{1}{2} \text{Cl}_2(g) + 2\text{OH}^-$		0.421 in 1 M NaOH
$\text{ClO}^- + \text{H}_2\text{O}(l) + 2e^- \rightleftharpoons \text{Cl}^- + 2\text{OH}^-$		0.890 in 1 M NaOH
$\text{HClO}_2 + 2\text{H}^+ + 2e^- \rightleftharpoons \text{HOCl} + \text{H}_2\text{O}(l)$	1.64

Chlorine	E (V)	E^o ́ (V)
$\text{ClO}_3^- + 2\text{H}^+ + e^- \rightleftharpoons \text{ClO}_2(g) + \text{H}_2\text{O}(l)$	1.175
$\text{ClO}_3^- + 3\text{H}^+ + 2e^- \rightleftharpoons \text{HClO}_2 + \text{H}_2\text{O}(l)$	1.181
$\text{ClO}_4^- + 2\text{H}^+ +2e^- \rightleftharpoons \text{ClO}_3^- + \text{H}_2\text{O}(l)$	1.201

Chromium	E (V)	E^o ́ (V)
$\text{Cr}^{3+} + 3e^- \rightleftharpoons \text{Cr}(s)$	–0.424
$\text{Cr}^{2+} + 2e^- \rightleftharpoons \text{Cr}(s)$	–0.90
$\text{Cr}_2\text{O}_7^{2-} + 14\text{H}^+ + 6e^- \rightleftharpoons 2\text{Cr}^{3+} + 7\text{H}_2\text{O}(l)$	1.36
$\text{CrO}_4^{2-} + 4\text{H}_2\text{O}(l) + 3e^- \rightleftharpoons \text{Cr(OH)}_4^- + 4\text{OH}^-$		–0.13 in 1 M NaOH

Cobalt	E (V)	E^o ́ (V)
$\text{Co}^{2+} + 2e^- \rightleftharpoons \text{Co}(s)$	–0.277
$\text{Co}^{3+} + 3e^- \rightleftharpoons \text{Co}(s)$	1.92
$\text{Co(NH}_3)_6^{3+} + e^- \rightleftharpoons \text{Co(NH}_3)_6^{2+}$	0.1
$\text{Co(OH)}_3(s) + e^- \rightleftharpoons \text{Co(OH)}_2(s) + \text{OH}^-$	0.17
$\text{Co(OH)}_2(s) + 2e^- \rightleftharpoons \text{Co}(s) + 2\text{OH}^-$	–0.746

Copper	E (V)	E^o ́ (V)
$\text{Cu}^+ + e^- \rightleftharpoons \text{Cu}(s)$	0.520
$\text{Cu}^{2+} + e^- \rightleftharpoons \text{Cu}^+$	0.159
$\text{Cu}^{2+} + 2e^- \rightleftharpoons \text{Cu}(s)$	0.3419
$\text{Cu}^{2+} + \text{I}^- + e^- \rightleftharpoons \text{CuI}(s)$	0.86
$\text{Cu}^{2+} + \text{Cl}^- + e^- \rightleftharpoons \text{CuCl}(s)$	0.559

Fluorine	E (V)	E^o ́ (V)
$\text{F}_2(g) + 2\text{H}^+ + 2e^- \rightleftharpoons 2\text{HF}(g)$	3.053
$\text{F}_2(g) + 2e^- \rightleftharpoons 2\text{F}^-$	2.87

Gallium	E (V)	E^o ́ (V)
$\text{Ga}^{3+} + 3e^- \rightleftharpoons \text{Ga}(s)$	–0.529

Gold	E (V)	E^o ́ (V)
$\text{Au}^+ + e^- \rightleftharpoons \text{Au}(s)$	1.83
$\text{Au}^{3+} + 2e^- \rightleftharpoons \text{Au}^+$	1.36
$\text{Au}^{3+} + 3e^- \rightleftharpoons \text{Au}(s)$	1.52
$\text{AuCl}_4^- + 3e^- \rightleftharpoons \text{Au}(s) + 4\text{Cl}^-$	1.002

Hydrogen	E (V)	E^o ́ (V)
$2\text{H}^+ + 2e^- \rightleftharpoons \text{H}_2 (g)$	0.00000
$\text{H}_2\text{O}(l) + e^- \rightleftharpoons \frac{1}{2} \text{H}_2(g) + \text{OH}^-$	–0.828

Iodine	E (V)	E^o ́ (V)
$\text{I}_2(s) + 2e^- \rightleftharpoons 2\text{I}^-$	0.5355

Iodine	E (V)	E^o ́ (V)
$\text{I}_3^- + 2e^- \rightleftharpoons 3\text{I}^-$	0.536
$\text{HIO} + \text{H}^+ + 2e^- \rightleftharpoons \text{I}^- + \text{H}_2\text{O}(l)$	0.985
$\text{IO}_3^- + 6\text{H}^+ + 5e^- \rightleftharpoons \frac{1}{2} \text{I}_2(s) + 3\text{H}_2\text{O}(l)$	1.195
$\text{IO}_3^- + 3\text{H}_2\text{O}(l) + 6e^- \rightleftharpoons \text{I}^- +6\text{OH}^-$	0.257

Iron	E (V)	E^o ́ (V)
$\text{Fe}^{2+} + 2e^- \rightleftharpoons \text{Fe}(s)$	–0.44
$\text{Fe}^{3+} + 3e^- \rightleftharpoons \text{Fe}(s)$	–0.037
$\text{Fe}^{3+} + e^- \rightleftharpoons \text{Fe}^{2+}$	0.771	0.70 in 1 M HCl 0.767 in 1 M HClO4 0.746 in 1 M HNO3 0.68 in 1 M H2SO4 0.44 in 0.3 M H3PO4
$\text{Fe(CN)}_6^{3-} + e^- \rightleftharpoons \text{Fe(CN)}_6^{4-}$	0.356
$\text{Fe(phen)}_3^{3+} + e^- \rightleftharpoons \text{Fe(phen)}_3^{2+}$	1.147

Lanthanum	E (V)	E^o ́ (V)
$\text{La}^{3+} + 3e^- \rightleftharpoons \text{La}(s)$	–2.38

Lead	E (V)	E^o ́ (V)
$\text{Pb}^{2+} + 2e^- \rightleftharpoons \text{Pb}(s)$	–0.126
$\text{PbO}_2(s) + 4\text{H}^+ + 2e^- \rightleftharpoons \text{Pb}^{2+} + 2\text{H}_2\text{O}(l)$	1.46
$\text{PbO}_2(s) + \text{SO}_4^{2-} + 4\text{H}^+ + 2e^- \rightleftharpoons \text{PbSO}_4(s) + 2\text{H}_2\text{O}(l)$	1.690
$\text{PbSO}_4(s) + 2e^- \rightleftharpoons \text{Pb}(s) + \text{SO}_4^{2-}$	–0.356

Lithium	E (V)	E^o ́ (V)
$\text{Li}^+ + e^- \rightleftharpoons \text{Li}(s)$	–3.040

Magnesium	E (V)	E^o ́ (V)
$\text{Mg}^{2+} + 2e^- \rightleftharpoons \text{Mg}(s)$	–2.356
$\text{Mg(OH)}_2(s) + 2e^- \rightleftharpoons \text{Mg}(s) + 2\text{OH}^-$	–2.687

Manganese	E (V)	E^o ́ (V)
$\text{Mn}^{2+} + 2e^- \rightleftharpoons \text{Mn}(s)$	–1.17
$\text{Mn}^{3+} + e^- \rightleftharpoons \text{Mn}^{2+}$	1.5
$\text{MnO}_2(s) + 4\text{H}^+ + 2e^- \rightleftharpoons \text{Mn}^{2+} + 2\text{H}_2\text{O}(l)$	1.23
$\text{MnO}_4^- + 4\text{H}^+ +3e^- \rightleftharpoons \text{MnO}_2(s) + 2\text{H}_2\text{O}(l)$	1.70
$\text{MnO}_4^- + 8\text{H}^+ + 5e^- \rightleftharpoons \text{Mn}^{2+} + 4\text{H}_2\text{O}(l)$	1.51
$\text{MnO}_4^- + 2\text{H}_2\text{O}(l) + 3e^- \rightleftharpoons \text{MnO}_2(s) + 4\text{OH}^-$	0.60

Mercury	E (V)	E^o ́ (V)
$\text{Hg}^{2+} + 2e^- \rightleftharpoons \text{Hg}(l)$	0.8535
$2\text{Hg}^{2+} +2e^- \rightleftharpoons \text{Hg}_2^{2+}$	0.911

Mercury	E (V)	E^o ́ (V)
$\text{Hg}_2^{2+} + 2e^- \rightleftharpoons 2\text{Hg}(l)$	0.7960
$\text{Hg}_2\text{Cl}_2(s) + 2e^- \rightleftharpoons 2\text{Hg}(l) + 2\text{Cl}^-$	0.2682
$\text{HgO}(s) + 2\text{H}^+ + 2e^- \rightleftharpoons \text{Hg}(l) + \text{H}_2\text{O}(l)$	0.926
$\text{Hg}_2\text{Br}_2(s) + 2e^- \rightleftharpoons 2\text{Hg}(l) + 2\text{Br}^-$	1.392
$\text{Hg}_2\text{I}_2(s) + 2e^- \rightleftharpoons 2\text{Hg}(l) + 2\text{I}^-$	–0.0405

Molybdenum	E (V)	E^o ́ (V)
$\text{Mo}^{3+} + 3e^- \rightleftharpoons \text{Mo}(s)$	–0.2
$\text{MoO}_2(s) + 4\text{H}^+ + 4e^- \rightleftharpoons \text{Mo}(s) + 2\text{H}_2\text{O}(l)$	–0.152
$\text{MoO}_4^{2-} + 4\text{H}_2\text{O}(l) + 6e^- \rightleftharpoons \text{Mo}(s) + 8\text{OH}^-$	–0.913

Nickel	E (V)	E^o ́ (V)
$\text{Ni}^{2+} + 2e^- \rightleftharpoons \text{Ni}(s)$	–0.257
$\text{Ni(OH)}_2(s) + 2e^- \rightleftharpoons \text{Ni}(s) + 2\text{OH}^-$	–0.72
$\text{Ni(NH}_3)_6^{2+} + 2e^- \rightleftharpoons \text{Ni}(s) + 6\text{NH}_3$	–0.49

Nitrogen	E (V)	E^o ́ (V)
$\text{N}_2(g) + 5\text{H}^+ + 4e^- \rightleftharpoons \text{N}_2\text{H}_5^+$	–0.23
$\text{N}_2\text{O}(g) + 2\text{H}^+ + 2e^- \rightleftharpoons \text{N}_2(g) + \text{H}_2\text{O}(l)$	1.77
$2\text{NO}(g) + 2\text{H}^+ + 2e^- \rightleftharpoons \text{N}_2\text{O}(g) + \text{H}_2\text{O}(l)$	1.59
$\text{HNO}_2 + \text{H}^+ + e^- \rightleftharpoons \text{NO}(g) + \text{H}_2\text{O}(l)$	0.996
$2\text{HNO}_2 + 4\text{H}^+ + 4e^- \rightleftharpoons \text{N}_2\text{O}(g) + 3\text{H}_2\text{O}(l)$	1.297
$\text{NO}_3^- + 3\text{H}^+ + 2e^- \rightleftharpoons \text{HNO}_2 + \text{H}_2\text{O}(l)$	0.94

Oxygen	E (V)	E^o ́ (V)
$\text{O}_2(g) + 2\text{H}^+ + 2e^- \rightleftharpoons \text{H}_2\text{O}_2$	0.695
$\text{O}_2(g) + 4\text{H}^+ + 4e^- \rightleftharpoons 2\text{H}_2\text{O}(l)$	1.229
$\text{H}_2\text{O}_2 + 2\text{H}^+ + 2e^- \rightleftharpoons 2\text{H}_2\text{O}(l)$	1.763
$\text{O}_2(g) + 2\text{H}_2\text{O}(l) + 4e^- \rightleftharpoons 4\text{OH}^-$	0.401
$\text{O}_3(g) + 2\text{H}^+ + 2e^- \rightleftharpoons \text{O}_2(g) + \text{H}_2\text{O}(l)$	2.07

Phosphorous	E (V)	E^o ́ (V)
$\text{P}(s, white) + 3\text{H}^+ + 3e^- \rightleftharpoons \text{PH}_3(g)$	–0.063
$\text{H}_3\text{PO}_3 + 2\text{H}^+ + 2e^- \rightleftharpoons \text{H}_3\text{PO}_2 + \text{H}_2\text{O}(l)$	–0.499
$\text{H}_3\text{PO}_4 + 2\text{H}^+ + 2e^- \rightleftharpoons \text{H}_3\text{PO}_3 + \text{H}_2\text{O}(l)$	–0.276

Platinum	E (V)	E^o ́ (V)
$\text{Pt}^{2+} + 2e^- \rightleftharpoons \text{Pt}(s)$	1.188
$\text{PtCl}_4^{2-} + 2e^- \rightleftharpoons \text{Pt}(s) + 4\text{Cl}^-$	0.758

Potasium	E (V)	E^o ́ (V)
$\text{K}^+ + e^- \rightleftharpoons \text{K}(s)$	–2.924

Ruthenium	E (V)	E^o ́ (V)
$\text{Ru}^{3+} + 3e^- \rightleftharpoons \text{Ru}(s)$	0.249
$\text{RuO}_2(s) + 4\text{H}^+ + 4e^- \rightleftharpoons \text{Ru}(s) + 2\text{H}_2\text{O}(l)$	0.68
$\text{Ru(NH}_3)_6^{3+} + e^- \rightleftharpoons \text{Ru(NH}_3)_6^{2+}$	0.10
$\text{Ru(CN)}_6^{3-} + e^- \rightleftharpoons \text{Ru(CN)}_6^{4-}$	0.86

Selenium	E (V)	E^o ́ (V)
$\text{Se}(s) + 2e^- \rightleftharpoons \text{Se}^{2-}$		–0.67 in 1 M NaOH
$\text{Se}(s) + 2\text{H}^+ + 2e^- \rightleftharpoons \text{H}_2\text{Se}(g)$	–0.115
$\text{H}_2\text{SeO}_3 + 4\text{H}^+ + 4e^- \rightleftharpoons \text{Se}(s) + 3\text{H}_2\text{O}(l)$	0.74
$\text{SeO}_4^{3-} + 4\text{H}^+ + e^- \rightleftharpoons \text{H}_2\text{SeO}_3 + \text{H}_2\text{O}(l)$	1.151

Silicon	E (V)	E^o ́ (V)
$\text{SiF}_6^{2-} + 4e^- \rightleftharpoons \text{Si}(s) + 6\text{F}^-$	–1.37
$\text{SiO}_2(s) + 4\text{H}^+ + 4e^- \rightleftharpoons \text{Si}(s) + 2\text{H}_2\text{O}(l)$	–0.909
$\text{SiO}_2(s) + 8\text{H}^+ + 8e^- \rightleftharpoons \text{SiH}_4(g) + 2\text{H}_2\text{O}(l)$	–0.516

Silver	E (V)	E^o ́ (V)
$\text{Ag}^+ + e^- \rightleftharpoons \text{Ag}(s)$	0.7996
$\text{AgBr}(s) + e^- \rightleftharpoons \text{Ag}(s) + \text{Br}^-$	0.071
$\text{Ag}_2\text{C}_2\text{O}_4(s) + 2e^- \rightleftharpoons 2\text{Ag}(s) + \text{C}_2\text{O}_4^{2-}$	0.47
$\text{AgCl}(s) + e^- \rightleftharpoons \text{Ag}(s) + \text{Cl}^-$	0.2223
$\text{AgI}(s) + e^- \rightleftharpoons \text{Ag}(s) + \text{I}^-$	–0.152
$\text{Ag}_2\text{S}(s) + 2e^- \rightleftharpoons 2\text{Ag}(s) + \text{S}^{2-}$	–0.71
$\text{Ag(NH}_3)_2^+ + e^- \rightleftharpoons \text{Ag}(s) + 2\text{NH}_3$	–0.373

Sodium	E (V)	E^o ́ (V)
$\text{Na}^+ + e^- \rightleftharpoons \text{Na}(s)$	–2.713

Strontium	E (V)	E^o ́ (V)
$\text{Sr}^{2+} + 2e^- \rightleftharpoons \text{Sr}(s)$	–2.89

Sulfur	E (V)	E^o ́ (V)
$\text{S}(s) + 2e^- \rightleftharpoons \text{S}^{2-}$	–0.407
$\text{S}(s) + 2\text{H}^+ + 2e^- \rightleftharpoons \text{H}_2\text{S}(g)$	0.144
$\text{S}_2\text{O}_6^{2-} + 4\text{H}^+ + 2e^- \rightleftharpoons 2\text{H}_2\text{SO}_3$	0.569
$\text{S}_2\text{O}_8^{2-} + 2e^- \rightleftharpoons 2\text{SO}_4^{2-}$	1.96
$\text{S}_4\text{O}_6^{2-} + 2e^- \rightleftharpoons 2\text{S}_2\text{O}_3^{2-}$	0.080
$2\text{SO}_3^{2-} + 2\text{H}_2\text{O}(l) + 2e^- \rightleftharpoons \text{S}_2\text{O}_4^{2-} + 4\text{OH}^-$	–1.13
$2\text{SO}_3^{2-} + 3\text{H}_2\text{O}(l) + 4e^- \rightleftharpoons \text{S}_2\text{O}_3^{2-} + 6\text{OH}^-$		–0.576 in 1 M NaOH
$2\text{SO}_4^{2-} + 4\text{H}^+ + 2e^- \rightleftharpoons \text{S}_2\text{O}_6^{2-} + 2\text{H}_2\text{O}(l)$	–0.25
$\text{SO}_4^{2-} + \text{H}_2\text{O}(l) + 2e^- \rightleftharpoons \text{SO}_3^{2-} + 2\text{OH}^-$	–0.936
$\text{SO}_4^{2-} + 4\text{H}^+ + 2e^- \rightleftharpoons \text{H}_2\text{SO}_3 + \text{H}_2\text{O}(l)$	0.172

Thallium	E (V)	E^o ́ (V)
$\text{Tl}^{3+} + 2e^- \rightleftharpoons \text{Tl}^+$		1.25 in 1 M HClO4 0.77 in 1 M HCl
$\text{Tl}^{3+} + 3e^- \rightleftharpoons \text{Tl}(s)$	0.742

Tin	E (V)	E^o ́ (V)
$\text{Sn}^{2+} + 2e^- \rightleftharpoons \text{Sn}(s)$		–0.19 in 1 M HCl
$\text{Sn}^{4+} + 2e^- \rightleftharpoons \text{Sn}^{2+}$	0.154	0.139 in 1 M HCl

Titanium	E (V)	E^o ́ (V)
$\text{Ti}^{2+} + 2e^- \rightleftharpoons \text{Ti}(s)$	–0.163
$\text{Ti}^{3+} + e^- \rightleftharpoons \text{Ti}^{2+}$	–0.37

Tungsten	E (V)	E^o ́ (V)
$\text{WO}_2(s) + 4\text{H}^+ + 4e^- \rightleftharpoons \text{W}(s) + 2\text{H}_2\text{O}(l)$	–0.119
$\text{WO}_3(s) + 6\text{H}^+ + 6e^- \rightleftharpoons \text{W}(s) + 3\text{H}_2\text{O}(l)$	–0.090

Uranium	E (V)	E^o ́ (V)
$\text{U}^{3+} + 3e^- \rightleftharpoons \text{U}(s)$	–1.66
$\text{U}^{4+} + e^- \rightleftharpoons \text{U}^{3+}$	–0.52
$\text{UO}_2^+ + 4\text{H}^+ + e^- \rightleftharpoons \text{U}^{4+} + 2\text{H}_2\text{O}(l)$	0.27
$\text{UO}_2^{2+} + e^- \rightleftharpoons \text{UO}_2^+$	0.16
$\text{UO}_2^{2+} + 4\text{H}^+ + 2e^- \rightleftharpoons \text{U}^{4+} + 2\text{H}_2\text{O}(l)$	0.327

Vanadium	E (V)	E^o ́ (V)
$\text{V}^{2+} + 2e^- \rightleftharpoons \text{V}(s)$	–1.13
$\text{V}^{3+} + e^- \rightleftharpoons \text{V}^{2+}$	–0.255
$\text{VO}^{2+} + 2\text{H}^+ + e^- \rightleftharpoons \text{V}^{3+} + \text{H}_2\text{O}(l)$	0.337
$\text{VO}_2^{+} + 2\text{H}^+ + e^- \rightleftharpoons \text{VO}^{2+} + \text{H}_2\text{O}(l)$	1.000

Zinc	E (V)	E^o ́ (V)
$\text{Zn}^{2+} + 2e^- \rightleftharpoons \text{Zn}(s)$	–0.7618
$\text{Zn(OH)}_4^{2-} + 2e^- \rightleftharpoons \text{Zn}(s) + 4\text{OH}^-$	–1.285
$\text{Zn(NH}_3)_4^{2+} + 2e^- \rightleftharpoons \text{Zn}(s) + 4\text{NH}_3$	–1.04
$\text{Zn(CN)}_4^{2-} + 2e^- \rightleftharpoons \text{Zn}(s) + 4\text{CN}^-$	–1.34