MOST SEARCHED REDUCTION POTENTIALS

FULL REDUCTION POTENTIAL TABLE

1. 1Fluorine / fluorideF₂ + 2e⁻ ⇌ 2F⁻+2.87 V
2. 2Ozone / oxygenO₃ + 2H⁺ + 2e⁻ ⇌ O₂ + H₂O+2.07 V
3. 3Peroxodisulfate / sulfateS₂O₈²⁻ + 2e⁻ ⇌ 2SO₄²⁻+2.01 V
4. 4Silver(II) / silver(I)Ag²⁺ + e⁻ ⇌ Ag⁺+1.98 V
5. 5Cobalt(III) / cobalt(II)Co³⁺ + e⁻ ⇌ Co²⁺+1.82 V
6. 6Hydrogen peroxide / waterH₂O₂ + 2H⁺ + 2e⁻ ⇌ 2H₂O+1.77 V
7. 7Cerium(IV) / cerium(III)Ce⁴⁺ + e⁻ ⇌ Ce³⁺+1.72 V
8. 8Manganate(VII) / manganese(II)MnO₄⁻ + 8H⁺ + 5e⁻ ⇌ Mn²⁺ + 4H₂O+1.51 V
9. 9Gold(III) / goldAu³⁺ + 3e⁻ ⇌ Au+1.50 V
10. 10Lead(IV) oxide / lead(II)PbO₂ + 4H⁺ + 2e⁻ ⇌ Pb²⁺ + 2H₂O+1.46 V
11. 11Chlorine / chlorideCl₂ + 2e⁻ ⇌ 2Cl⁻+1.36 V
12. 12Dichromate(VI) / chromium(III)Cr₂O₇²⁻ + 14H⁺ + 6e⁻ ⇌ 2Cr³⁺ + 7H₂O+1.33 V
13. 13Manganese(IV) oxide / manganese(II)MnO₂ + 4H⁺ + 2e⁻ ⇌ Mn²⁺ + 2H₂O+1.23 V
14. 14Oxygen / water (acidic)O₂ + 4H⁺ + 4e⁻ ⇌ 2H₂O+1.23 V
15. 15Platinum(II) / platinumPt²⁺ + 2e⁻ ⇌ Pt+1.19 V
16. 16Aqueous bromine / bromideBr₂(aq) + 2e⁻ ⇌ 2Br⁻+1.09 V
17. 17Bromine / bromideBr₂ + 2e⁻ ⇌ 2Br⁻+1.07 V
18. 18Vanadium(V) / vanadium(IV)VO₂⁺ + 2H⁺ + e⁻ ⇌ VO²⁺ + H₂O+1.00 V
19. 19Nitrate / nitrogen monoxideNO₃⁻ + 4H⁺ + 3e⁻ ⇌ NO + 2H₂O+0.96 V
20. 20Hypochlorite / chlorideClO⁻ + H₂O + 2e⁻ ⇌ Cl⁻ + 2OH⁻+0.89 V
21. 21Copper(II) / copper(I) iodideCu²⁺ + I⁻ + e⁻ ⇌ CuI+0.86 V
22. 22Mercury(II) / mercuryHg²⁺ + 2e⁻ ⇌ Hg+0.85 V
23. 23Silver(I) / silverAg⁺ + e⁻ ⇌ Ag+0.80 V
24. 24Iron(III) / iron(II)Fe³⁺ + e⁻ ⇌ Fe²⁺+0.77 V
25. 25Oxygen / hydrogen peroxideO₂ + 2H⁺ + 2e⁻ ⇌ H₂O₂+0.68 V
26. 26Manganate(VII) / MnO₂ (alkaline)MnO₄⁻ + 2H₂O + 3e⁻ ⇌ MnO₂ + 4OH⁻+0.59 V
27. 27Iodine / iodideI₂ + 2e⁻ ⇌ 2I⁻+0.54 V
28. 28Copper(I) / copperCu⁺ + e⁻ ⇌ Cu+0.52 V
29. 29NiMH battery coupleNiO(OH) + H₂O + e⁻ ⇌ Ni(OH)₂ + OH⁻+0.52 V
30. 30Oxygen / hydroxide (alkaline)O₂ + 2H₂O + 4e⁻ ⇌ 4OH⁻+0.40 V
31. 31Copper(II) / copperCu²⁺ + 2e⁻ ⇌ Cu+0.34 V
32. 32Vanadium(IV) / vanadium(III)VO²⁺ + 2H⁺ + e⁻ ⇌ V³⁺ + H₂O+0.34 V
33. 33Calomel electrodeHg₂Cl₂ + 2e⁻ ⇌ 2Hg + 2Cl⁻+0.27 V
34. 34Nitrogen / ammoniumN₂ + 8H⁺ + 6e⁻ ⇌ 2NH₄⁺+0.27 V
35. 35Silver–silver chloride electrodeAgCl + e⁻ ⇌ Ag + Cl⁻+0.22 V
36. 36Sulfate / sulfur dioxideSO₄²⁻ + 4H⁺ + 2e⁻ ⇌ SO₂ + 2H₂O+0.17 V
37. 37Copper(II) / copper(I)Cu²⁺ + e⁻ ⇌ Cu⁺+0.15 V
38. 38Tin(IV) / tin(II)Sn⁴⁺ + 2e⁻ ⇌ Sn²⁺+0.15 V
39. 39Sulfur / hydrogen sulfideS + 2H⁺ + 2e⁻ ⇌ H₂S+0.14 V
40. 40Tetrathionate / thiosulfateS₄O₆²⁻ + 2e⁻ ⇌ 2S₂O₃²⁻+0.09 V
41. 41Silver bromide / silverAgBr + e⁻ ⇌ Ag + Br⁻+0.07 V
42. 42Standard hydrogen electrode2H⁺ + 2e⁻ ⇌ H₂0.00 V
43. 43Lead(II) / leadPb²⁺ + 2e⁻ ⇌ Pb-0.13 V
44. 44Tin(II) / tinSn²⁺ + 2e⁻ ⇌ Sn-0.14 V
45. 45Nickel(II) / nickelNi²⁺ + 2e⁻ ⇌ Ni-0.25 V
46. 46Vanadium(III) / vanadium(II)V³⁺ + e⁻ ⇌ V²⁺-0.26 V
47. 47Cobalt(II) / cobaltCo²⁺ + 2e⁻ ⇌ Co-0.28 V
48. 48Lead sulfate / leadPbSO₄ + 2e⁻ ⇌ Pb + SO₄²⁻-0.36 V
49. 49Cadmium(II) / cadmiumCd²⁺ + 2e⁻ ⇌ Cd-0.40 V
50. 50Chromium(III) / chromium(II)Cr³⁺ + e⁻ ⇌ Cr²⁺-0.41 V
51. 51Iron(II) / ironFe²⁺ + 2e⁻ ⇌ Fe-0.44 V
52. 52Sulfur / sulfideS + 2e⁻ ⇌ S²⁻-0.48 V
53. 53Carbon dioxide / ethanedioic acid2CO₂ + 2H⁺ + 2e⁻ ⇌ H₂C₂O₄-0.49 V
54. 54Chromium(III) / chromiumCr³⁺ + 3e⁻ ⇌ Cr-0.74 V
55. 55Zinc(II) / zincZn²⁺ + 2e⁻ ⇌ Zn-0.76 V
56. 56Water / hydrogen (alkaline)2H₂O + 2e⁻ ⇌ H₂ + 2OH⁻-0.83 V
57. 57Chromium(II) / chromiumCr²⁺ + 2e⁻ ⇌ Cr-0.91 V
58. 58Vanadium(II) / vanadiumV²⁺ + 2e⁻ ⇌ V-1.18 V
59. 59Manganese(II) / manganeseMn²⁺ + 2e⁻ ⇌ Mn-1.19 V
60. 60Zinc hydroxide / zinc (alkaline)Zn(OH)₂ + 2e⁻ ⇌ Zn + 2OH⁻-1.25 V
61. 61Titanium(II) / titaniumTi²⁺ + 2e⁻ ⇌ Ti-1.63 V
62. 62Aluminium(III) / aluminiumAl³⁺ + 3e⁻ ⇌ Al-1.66 V
63. 63Uranium(III) / uraniumU³⁺ + 3e⁻ ⇌ U-1.80 V
64. 64Beryllium(II) / berylliumBe²⁺ + 2e⁻ ⇌ Be-1.85 V
65. 65Scandium(III) / scandiumSc³⁺ + 3e⁻ ⇌ Sc-2.08 V
66. 66Cerium(III) / ceriumCe³⁺ + 3e⁻ ⇌ Ce-2.34 V
67. 67Magnesium(II) / magnesiumMg²⁺ + 2e⁻ ⇌ Mg-2.37 V
68. 68Lanthanum(III) / lanthanumLa³⁺ + 3e⁻ ⇌ La-2.38 V
69. 69Sodium(I) / sodiumNa⁺ + e⁻ ⇌ Na-2.71 V
70. 70Calcium(II) / calciumCa²⁺ + 2e⁻ ⇌ Ca-2.87 V
71. 71Strontium(II) / strontiumSr²⁺ + 2e⁻ ⇌ Sr-2.89 V
72. 72Barium(II) / bariumBa²⁺ + 2e⁻ ⇌ Ba-2.91 V
73. 73Potassium(I) / potassiumK⁺ + e⁻ ⇌ K-2.93 V
74. 74Rubidium(I) / rubidiumRb⁺ + e⁻ ⇌ Rb-2.98 V
75. 75Caesium(I) / caesiumCs⁺ + e⁻ ⇌ Cs-3.03 V
76. 76Lithium(I) / lithiumLi⁺ + e⁻ ⇌ Li-3.04 V
77. 77Lithium-ion anode coupleLi⁺ + e⁻ + C₆ ⇌ LiC₆-3.04 V

RULES WORTH MEMORISING

• A standard reduction potential is E° for the half-equation written as a reduction (electrons on the left).
• The more positive E°red, the more easily the species is reduced — so it is the stronger oxidising agent.
• The more negative E°red, the harder it is to reduce — so its reduced form is the stronger reducing agent.
• Reversing a half-equation flips the sign: E°ox = −E°red. Multiplying a half-equation does NOT change E°.
• E°cell = E°red(cathode) − E°red(anode); a positive E°cell means the reaction is feasible.
• ΔG° = −nFE° with F = 96 500 C mol⁻¹, so a positive E° gives a negative ΔG°.
• All values are for 298 K, 1 mol dm⁻³ solutions and 100 kPa gases, measured against the standard hydrogen electrode.