Loading [MathJax]/jax/output/HTML-CSS/jax.js
Skip to main content
Library homepage
 

Text Color

Text Size

 

Margin Size

 

Font Type

Enable Dyslexic Font
Chemistry LibreTexts

16.13: Standard Reduction Potentials

  1. CCBYNCSA
  2. Last updated
    Dec 17, 2021
  3. Save as PDF

( \newcommand{\kernel}{\mathrm{null}\,}\)

The following table provides Eo and Eo ́ 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– ⇌ HAsO2 +2H2O

becomes

H3AsO4 + 2H3O+ +2e– ⇌ HAsO2 +4H2O

Conditions for formal potentials (Eo ́) 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 Eo value of –1.285 V for

Zn(OH)2−4+2e−⇌Zn(s)+4OH−

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) Eo ́ (V)

Al3++3e−⇌Al(s)

 –1.676  
Al(OH)−4+3e−⇌Al(s)+4OH− –2.310  

AlF3−6+3e−⇌Al(s)+6F−

 –2.07  
Antimony E (V) Eo ́ (V)
Sb+3H++3e−⇌SbH3(g) –0.510  
Sb2O5+6H++4e−⇌2SbO++3H2O(l) 0.605  
SbO++2H++3e−⇌Sb(s)+H2O(l) 0.212  
Arsenic E (V) Eo ́ (V)
As(s)+3H++3e−⇌AsH3(g) –0.225  
H3AsO4+2H++2e−⇌HAsO2+2H2O(l) 0.560  
HAsO2+3H++3e−⇌As(s)+2H2O(l) 0.240  
Barium E (V) Eo ́ (V)

Ba2++2e−⇌Ba(s)

 –2.92  

BaO(s)+2H++2e−⇌Ba(s)+H2O(l)

 –2.166  

 

Beryllium E (V) Eo ́ (V)

Be2++2e−⇌Be(s)

 –1.99  
Bismuth E (V) Eo ́ (V)

Bi3++3e−⇌Bi(s)

0.317

  
BiCl−4+3e−⇌Bi(s)+4Cl−

0.199

  
Boron E (V) Eo ́ (V)

B(OH)3+3H++3e−⇌B(s)+3H2O(l)

–0.890

  

B(OH)−4+3e−⇌B(s)+4OH−

–1.811

  
Bromine E (V) Eo ́ (V)
Br2(l)+2e−⇌2Br−

1.087

  

HOBr+H++2e−⇌Br−+H2O(l)

1.341

  

HOBr+H++e−⇌12Br2+H2O(l)

1.604

  

BrO−+H2O(l)+2e−⇌Br−+2OH−

  

0.76 in 1 M NaOH

BrO−3+6H++5e−⇌12Br2(l)+3H2O(l)

1.5

  

BrO−3+6H++6e−⇌Br−+3H2O(l)

1.478

  
Cadmium E (V) Eo ́ (V)

Cd2++2e−⇌Cd(s)

–0.4030

  

Cd(CN)2−4+2e−⇌Cd(s)+4CN−

–0.943

  

Cd(NH3)2+4+2e−⇌Cd(s)+4NH3

–0.622

  
Calcium E (V) Eo ́ (V)

Ca2++2e−⇌Ca(s)

–2.84

  
Carbon E (V) Eo ́ (V)

CO2(g)+2H++2e−⇌CO(g)+H2O(l)

–0.106

  

CO2(g)+2H++2e−⇌HCO2H

–0.20

  

2CO2(g)+2H++2e−⇌H2C2O4

–0.481

  

HCHO+2H++2e−⇌CH3OH

0.2323

  
Cerium E (V) Eo ́ (V)

Ce3++3e−⇌Ce(s)

–2.336

  

Ce4++e−⇌Ce3+

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) Eo ́ (V)

Cl2(g)+2e−⇌2Cl−

1.396

  

ClO−+H2O(l)+e−⇌12Cl2(g)+2OH−

  

0.421 in 1 M NaOH

ClO−+H2O(l)+2e−⇌Cl−+2OH−

  

0.890 in 1 M NaOH

HClO2+2H++2e−⇌HOCl+H2O(l)

1.64

  
Chlorine E (V) Eo ́ (V)

ClO−3+2H++e−⇌ClO2(g)+H2O(l)

1.175

  

ClO−3+3H++2e−⇌HClO2+H2O(l)

1.181

  

ClO−4+2H++2e−⇌ClO−3+H2O(l)

1.201

  
Chromium E (V) Eo ́ (V)

Cr3++3e−⇌Cr(s)

–0.424

  

Cr2++2e−⇌Cr(s)

–0.90

  

Cr2O2−7+14H++6e−⇌2Cr3++7H2O(l)

1.36

  

CrO2−4+4H2O(l)+3e−⇌Cr(OH)−4+4OH−

   –0.13 in 1 M NaOH
Cobalt E (V) Eo ́ (V)

Co2++2e−⇌Co(s)

–0.277

  

Co3++3e−⇌Co(s)

1.92

  

Co(NH3)3+6+e−⇌Co(NH3)2+6

0.1

  

Co(OH)3(s)+e−⇌Co(OH)2(s)+OH−

0.17

  

Co(OH)2(s)+2e−⇌Co(s)+2OH−

–0.746

  
Copper E (V) Eo ́ (V)

Cu++e−⇌Cu(s)

0.520

  

Cu2++e−⇌Cu+

0.159

  

Cu2++2e−⇌Cu(s)

0.3419

  

Cu2++I−+e−⇌CuI(s)

0.86

  

Cu2++Cl−+e−⇌CuCl(s)

0.559

  
Fluorine E (V) Eo ́ (V)

F2(g)+2H++2e−⇌2HF(g)

3.053

  

F2(g)+2e−⇌2F−

2.87

  
Gallium E (V) Eo ́ (V)

Ga3++3e−⇌Ga(s)

 –0.529  
Gold E (V) Eo ́ (V)

Au++e−⇌Au(s)

1.83

  

Au3++2e−⇌Au+

1.36

  

Au3++3e−⇌Au(s)

1.52

  

AuCl−4+3e−⇌Au(s)+4Cl−

1.002

  
Hydrogen E (V) Eo ́ (V)

2H++2e−⇌H2(g)

0.00000

  

H2O(l)+e−⇌12H2(g)+OH−

–0.828

  
Iodine E (V) Eo ́ (V)

I2(s)+2e−⇌2I−

0.5355

  
Iodine E (V) Eo ́ (V)

I−3+2e−⇌3I−

0.536

  

HIO+H++2e−⇌I−+H2O(l)

0.985

  

IO−3+6H++5e−⇌12I2(s)+3H2O(l)

1.195

  

IO−3+3H2O(l)+6e−⇌I−+6OH−

0.257

  
Iron E (V) Eo ́ (V)

Fe2++2e−⇌Fe(s)

–0.44

  

Fe3++3e−⇌Fe(s)

–0.037

  

Fe3++e−⇌Fe2+

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

Fe(CN)3−6+e−⇌Fe(CN)4−6

0.356

  

Fe(phen)3+3+e−⇌Fe(phen)2+3

1.147

  
Lanthanum E (V) Eo ́ (V)

La3++3e−⇌La(s)

–2.38

  
Lead E (V) Eo ́ (V)

Pb2++2e−⇌Pb(s)

–0.126

  

PbO2(s)+4H++2e−⇌Pb2++2H2O(l)

1.46

  

PbO2(s)+SO2−4+4H++2e−⇌PbSO4(s)+2H2O(l)

1.690

  

PbSO4(s)+2e−⇌Pb(s)+SO2−4

–0.356

  
Lithium E (V) Eo ́ (V)

Li++e−⇌Li(s)

–3.040

  
Magnesium E (V) Eo ́ (V)

Mg2++2e−⇌Mg(s)

–2.356

  

Mg(OH)2(s)+2e−⇌Mg(s)+2OH−

–2.687

  
Manganese E (V) Eo ́ (V)

Mn2++2e−⇌Mn(s)

–1.17

  

Mn3++e−⇌Mn2+

1.5

  

MnO2(s)+4H++2e−⇌Mn2++2H2O(l)

1.23

  

MnO−4+4H++3e−⇌MnO2(s)+2H2O(l)

1.70

  

MnO−4+8H++5e−⇌Mn2++4H2O(l)

1.51

  

MnO−4+2H2O(l)+3e−⇌MnO2(s)+4OH−

0.60

  
Mercury E (V) Eo ́ (V)

Hg2++2e−⇌Hg(l)

0.8535

  

2Hg2++2e−⇌Hg2+2

0.911

  
Mercury E (V) Eo ́ (V)

Hg2+2+2e−⇌2Hg(l)

0.7960

  

Hg2Cl2(s)+2e−⇌2Hg(l)+2Cl−

0.2682

  

HgO(s)+2H++2e−⇌Hg(l)+H2O(l)

0.926

  

Hg2Br2(s)+2e−⇌2Hg(l)+2Br−

1.392

  

Hg2I2(s)+2e−⇌2Hg(l)+2I−

–0.0405

  
Molybdenum E (V) Eo ́ (V)

Mo3++3e−⇌Mo(s)

–0.2

  

MoO2(s)+4H++4e−⇌Mo(s)+2H2O(l)

–0.152

  

MoO2−4+4H2O(l)+6e−⇌Mo(s)+8OH−

–0.913

  
Nickel E (V) Eo ́ (V)

Ni2++2e−⇌Ni(s)

–0.257

  

Ni(OH)2(s)+2e−⇌Ni(s)+2OH−

–0.72

  

Ni(NH3)2+6+2e−⇌Ni(s)+6NH3

–0.49

  
Nitrogen E (V) Eo ́ (V)

N2(g)+5H++4e−⇌N2H+5

–0.23

  

N2O(g)+2H++2e−⇌N2(g)+H2O(l)

1.77

  

2NO(g)+2H++2e−⇌N2O(g)+H2O(l)

1.59

  

HNO2+H++e−⇌NO(g)+H2O(l)

0.996

  

2HNO2+4H++4e−⇌N2O(g)+3H2O(l)

1.297

  

NO−3+3H++2e−⇌HNO2+H2O(l)

0.94

  
Oxygen E (V) Eo ́ (V)

O2(g)+2H++2e−⇌H2O2

0.695

  

O2(g)+4H++4e−⇌2H2O(l)

1.229

  

H2O2+2H++2e−⇌2H2O(l)

1.763

  

O2(g)+2H2O(l)+4e−⇌4OH−

0.401

  

O3(g)+2H++2e−⇌O2(g)+H2O(l)

2.07

  
Phosphorous E (V) Eo ́ (V)

P(s,white)+3H++3e−⇌PH3(g)

–0.063

  

H3PO3+2H++2e−⇌H3PO2+H2O(l)

–0.499

  

H3PO4+2H++2e−⇌H3PO3+H2O(l)

–0.276

  
Platinum E (V) Eo ́ (V)

Pt2++2e−⇌Pt(s)

1.188

  

PtCl2−4+2e−⇌Pt(s)+4Cl−

0.758

  
Potasium E (V) Eo ́ (V)

K++e−⇌K(s)

–2.924

  
Ruthenium E (V) Eo ́ (V)

Ru3++3e−⇌Ru(s)

0.249

  

RuO2(s)+4H++4e−⇌Ru(s)+2H2O(l)

0.68

  

Ru(NH3)3+6+e−⇌Ru(NH3)2+6

0.10

  

Ru(CN)3−6+e−⇌Ru(CN)4−6

0.86

  
Selenium E (V) Eo ́ (V)

Se(s)+2e−⇌Se2−

  

–0.67 in 1 M NaOH

Se(s)+2H++2e−⇌H2Se(g)

–0.115

  

H2SeO3+4H++4e−⇌Se(s)+3H2O(l)

0.74

  

SeO3−4+4H++e−⇌H2SeO3+H2O(l)

1.151

  
Silicon E (V) Eo ́ (V)

SiF2−6+4e−⇌Si(s)+6F−

–1.37

  

SiO2(s)+4H++4e−⇌Si(s)+2H2O(l)

–0.909

  

SiO2(s)+8H++8e−⇌SiH4(g)+2H2O(l)

–0.516

  
Silver E (V) Eo ́ (V)

Ag++e−⇌Ag(s)

0.7996

  

AgBr(s)+e−⇌Ag(s)+Br−

0.071

  

Ag2C2O4(s)+2e−⇌2Ag(s)+C2O2−4

0.47

  

AgCl(s)+e−⇌Ag(s)+Cl−

0.2223

  

AgI(s)+e−⇌Ag(s)+I−

–0.152

  

Ag2S(s)+2e−⇌2Ag(s)+S2−

–0.71

  

Ag(NH3)+2+e−⇌Ag(s)+2NH3

–0.373

  
Sodium E (V) Eo ́ (V)

Na++e−⇌Na(s)

–2.713

  
Strontium E (V) Eo ́ (V)

Sr2++2e−⇌Sr(s)

–2.89

  
Sulfur E (V) Eo ́ (V)

S(s)+2e−⇌S2−

–0.407

  

S(s)+2H++2e−⇌H2S(g)

0.144

  

S2O2−6+4H++2e−⇌2H2SO3

0.569

  

S2O2−8+2e−⇌2SO2−4

1.96

  

S4O2−6+2e−⇌2S2O2−3

0.080

  

2SO2−3+2H2O(l)+2e−⇌S2O2−4+4OH−

–1.13

  

2SO2−3+3H2O(l)+4e−⇌S2O2−3+6OH−

  

–0.576 in 1 M NaOH

2SO2−4+4H++2e−⇌S2O2−6+2H2O(l)

–0.25

  

SO2−4+H2O(l)+2e−⇌SO2−3+2OH−

–0.936

  

SO2−4+4H++2e−⇌H2SO3+H2O(l)

0.172

  
Thallium E (V) Eo ́ (V)

Tl3++2e−⇌Tl+

  

1.25 in 1 M HClO4

0.77 in 1 M HCl

Tl3++3e−⇌Tl(s)

 0.742  
Tin E (V) Eo ́ (V)

Sn2++2e−⇌Sn(s)

  

–0.19 in 1 M HCl

Sn4++2e−⇌Sn2+

0.154

0.139 in 1 M HCl
Titanium E (V) Eo ́ (V)

Ti2++2e−⇌Ti(s)

–0.163

  

Ti3++e−⇌Ti2+

–0.37

  
Tungsten E (V) Eo ́ (V)

WO2(s)+4H++4e−⇌W(s)+2H2O(l)

–0.119

  

WO3(s)+6H++6e−⇌W(s)+3H2O(l)

–0.090

  
Uranium E (V) Eo ́ (V)

U3++3e−⇌U(s)

–1.66

  

U4++e−⇌U3+

–0.52

  

UO+2+4H++e−⇌U4++2H2O(l)

0.27

  

UO2+2+e−⇌UO+2

0.16

  

UO2+2+4H++2e−⇌U4++2H2O(l)

0.327

  
Vanadium E (V) Eo ́ (V)

V2++2e−⇌V(s)

–1.13

  

V3++e−⇌V2+

–0.255

  

VO2++2H++e−⇌V3++H2O(l)

0.337

  

VO+2+2H++e−⇌VO2++H2O(l)

1.000

  
Zinc E (V) Eo ́ (V)

Zn2++2e−⇌Zn(s)

–0.7618

  

Zn(OH)2−4+2e−⇌Zn(s)+4OH−

–1.285

  

Zn(NH3)2+4+2e−⇌Zn(s)+4NH3

–1.04

  

Zn(CN)2−4+2e−⇌Zn(s)+4CN−

–1.34

  

This page titled 16.13: Standard Reduction Potentials is shared under a CC BY-NC-SA 4.0 license and was authored, remixed, and/or curated by David Harvey.

Support Center

How can we help?