Table des potentiels standards Couples rédox, équation rédox et potentiels standards (E°) des couples oxydoréduction.

Couple rédox Equation rédox +

Ag /Ag

+

-

Ag + e

+

+

-

Au /Au Br2/Br

Ag

Au + e

-

2

BrO3 /Br2 -

BrO3 /Br

0,7996

Au -

Br + 2e

-

Potentiel standard en V 1,692

2Br

-

+

-

-

+

-

-

1,087

BrO3 + 6H + 5e

-

1/2Br2+ 3 H2O -

BrO3 + 6H + 6e

Br + 3 H2O

Cr2O72-/Cr3+

Cr2O72- + 14H++ 6e-

ClO-/Cl-

ClO- + H2O + 2e-

2+

Cu /Cu Fe /Fe 3+

Cu

0,342

-

Fe

-0,447

-

Fe

-0,037

+ 2e + 3e

3+

Fe /Fe

-

Fe

+

2+

+e

+

Fe

-

0,771

H /H2

H +e

H2O/H2

2H2O + 2e-

H2+ 2OH-

2+

2+

2+

Hg / Hg2 I2/I

2+

-

H2

2Hg + 2e I2 + 2e 2+

Mg /Mg 3+

Mg

2+

Mn /Mn -

2+

MnO4 /Mn +

3+

Mn

Hg2 2I

+ 2e +e

Mn +

-

Ni2+/Ni

Ni2+ + 2ePb

PbO2/Pb 2+

-

+ 2e

Pt

S4O62-/S2O32-

S4O62- + 2e-

+ 2e

2+

-

Sn

Sn4+/Sn2+

Sn4+ + 2e-

Zn /Zn  

-

Ti

2+

-

+ 2e

2+

Zn

+ 2e

Pb + 2H2O

+ 2e

1.455 1,18

2S2O32-

0,08

Sn

-0,1375

Sn2+

0,151

Ti -

1,229 -0,126

2+

Pt

Sn /Sn

2+

2H2O

PbO2+ 4H + 2e -

1,507 -0,257

Pb

Pt /Pt 2+

Mn + 4 H2O

Ni -

+

2+

1,542 2+

-2,71

O2 + 4H + 4e 2+

Ti /Ti

-

Na

+

Pb /Pb

-2,37

2+

Na + e

2+

0,536

MnO4 + 8H + 5e

2+

-0,92

Mg

-

Na /Na

2+

-0,828

-

-

-

+

O2/H2O

-0,00

-

-

2+

0,81

+ 2e

Fe 2+

Cl-+ 2 OH-

2+ 3+

Fe /Fe

2Cr3++ 7 H2O 1,23

-

Fe

3+

1,423

2+

Cu

2+

1,482

Zn

-1,63 0,76

Electrochemical Series Petr Vanýsek There are three tables for this electrochemical series. Each table lists standard reduction potentials, E° values, at 298.15 K (25 °C), and at a pressure of 101.325 kPa (1 atm). Table 1 is an alphabetical listing of the elements, according to the symbol of the elements. Thus, data for silver (Ag) precede those for aluminum (Al). Table 2 lists only those reduction reactions that have E° values positive in respect to the standard hydrogen electrode. In Table 2, the reactions are listed in the order of increasing positive potential, and they range from 0.0000 V to + 3.4 V. Table 3 lists only those reduction potentials which have E° negative with respect to the standard hydrogen electrode. In Table 3, the reactions are listed in the order of decreasing potential and range from 0.0000 V to –4.10 V. The reliability of the potentials is not the same for all the data. Typically, the values with fewer significant figures have lower

reliability. The values of reduction potentials, in particular those of less common reactions, are not definite; they are subject to occasional revisions. Abbreviations: ac = acetate; bipy = 2,2´-dipyridine, or bipyridine; en = ethylenediamine; phen = 1,10-phenanthroline.

References 1. Milazzo, G., Caroli, S., and Sharma, V. K. Tables of Standard Electrode Potentials, Wiley, Chichester, 1978. 2. Bard, A. J., Parsons, R., and Jordan, J. Standard Potentials in Aqueous Solutions, Marcel Dekker, New York, 1985. 3. Bratsch, S. G. J. Phys. Chem. Ref. Data, 18, 1–21, 1989.

TABLE 1. Alphabetical Listing Reaction Ac3+ + 3 e ⇌ Ac Ag+ + e ⇌ Ag Ag2+ + e ⇌ Ag+ Ag(ac) + e ⇌ Ag + (ac)– AgBr + e ⇌ Ag + Br– AgBrO3 + e ⇌ Ag + BrO3– Ag2C2O4 + 2 e ⇌ 2 Ag + C2O42– AgCl + e ⇌ Ag + Cl– AgCN + e ⇌ Ag + CN– Ag2CO3 + 2 e ⇌ 2 Ag + CO32– Ag2CrO4 + 2 e ⇌ 2 Ag + CrO42– AgF + e ⇌ Ag + F– Ag4[Fe(CN)6] + 4 e ⇌ 4 Ag + [Fe(CN)6]4– AgI + e ⇌ Ag + I– AgIO3 + e ⇌ Ag + IO3– Ag2MoO4 + 2 e ⇌ 2 Ag + MoO42– AgNO2 + e ⇌ Ag + 2 NO2– Ag2O + H2O + 2 e ⇌ 2 Ag + 2 OH– Ag2O3 + H2O + 2 e ⇌ 2 AgO + 2 OH– Ag3+ + 2 e ⇌ Ag+ Ag3+ + e ⇌ Ag2+ Ag2O2 + 4 H+ + e ⇌ 2 Ag + 2 H2O 2 AgO + H2O + 2 e ⇌ Ag2O + 2 OH– AgOCN + e ⇌ Ag + OCN– Ag2S + 2 e ⇌ 2 Ag + S2– Ag2S + 2 H+ + 2 e ⇌ 2 Ag + H2S AgSCN + e ⇌ Ag + SCN– Ag2SeO3 + 2 e ⇌ 2 Ag + SeO42– Ag2SO4 + 2 e ⇌ 2 Ag + SO42– Ag2WO4 + 2 e ⇌ 2 Ag + WO42– Al3+ + 3 e ⇌ Al Al(OH)3 + 3 e ⇌ Al + 3 OH– Al(OH)4– + 3 e ⇌ Al + 4 OH– H2AlO3– + H2O + 3 e ⇌ Al + 4 OH– AlF63– + 3 e ⇌ Al + 6 F– Am4+ + e ⇌ Am3+ Am2+ + 2 e ⇌ Am Am3+ + 3 e ⇌ Am Am3+ + e ⇌ Am2+

8-20

E°/V –2.20 0.7996 1.980 0.643 0.07133 0.546 0.4647 0.22233 –0.017 0.47 0.4470 0.779 0.1478 –0.15224 0.354 0.4573 0.564 0.342 0.739 1.9 1.8 1.802 0.607 0.41 –0.691 –0.0366 0.08951 0.3629 0.654 0.4660 –1.662 –2.31 –2.328 –2.33 –2.069 2.60 –1.9 –2.048 –2.3

Reaction As + 3 H+ + 3 e ⇌ AsH3 As2O3 + 6 H+ + 6 e ⇌ 2 As + 3 H2O HAsO2 + 3 H+ + 3 e ⇌ As + 2 H2O AsO2– + 2 H2O + 3 e ⇌ As + 4 OH– H3AsO4 + 2 H+ + 2 e– ⇌ HAsO2 + 2 H2O AsO43– + 2 H2O + 2 e ⇌ AsO2– + 4 OH– At2 + 2 e ⇌ 2 At– Au+ + e ⇌ Au Au3+ + 2 e ⇌ Au+ Au3+ + 3 e ⇌ Au Au2+ + e – ⇌ Au+ AuOH2+ + H+ + 2 e ⇌ Au+ + H2O AuBr2– + e ⇌ Au + 2 Br– AuBr4– + 3 e ⇌ Au + 4 Br– AuCl4– + 3 e ⇌ Au + 4 Cl– Au(OH)3 + 3 H+ + 3 e ⇌ Au + 3 H2O H2BO3– + 5 H2O + 8 e ⇌ BH4– + 8 OH– H2BO3– + H2O + 3 e ⇌ B + 4 OH– H3BO3 + 3 H+ + 3 e ⇌ B + 3 H2O B(OH)3 + 7 H+ + 8 e ⇌ BH4– + 3 H2O Ba2+ + 2 e ⇌ Ba Ba2+ + 2 e ⇌ Ba(Hg) Ba(OH)2 + 2 e ⇌ Ba + 2 OH– Be2+ + 2 e ⇌ Be Be2O32– + 3 H2O + 4 e ⇌ 2 Be + 6 OH– p–benzoquinone + 2 H+ + 2 e ⇌ hydroquinone Bi+ + e ⇌ Bi Bi3+ + 3 e ⇌ Bi Bi3+ + 2 e ⇌ Bi+ Bi + 3 H+ + 3 e ⇌ BiH3 BiCl4– + 3 e ⇌ Bi + 4 Cl– Bi2O3 + 3 H2O + 6 e ⇌ 2 Bi + 6 OH– Bi2O4 + 4 H+ + 2 e ⇌ 2 BiO+ + 2 H2O BiO+ + 2 H+ + 3 e ⇌ Bi + H2O BiOCl + 2 H+ + 3 e ⇌ Bi + Cl– + H2O Bk4+ + e ⇌ Bk3+ Bk2+ + 2 e ⇌ Bk Bk3+ + e ⇌ Bk2+

E°/V –0.608 0.234 0.248 –0.68 0.560 –0.71 0.3 1.692 1.401 1.498 1.8 1.32 0.959 0.854 1.002 1.45 –1.24 –1.79 –0.8698 –0.481 –2.912 –1.570 –2.99 –1.847 –2.63 0.6992 0.5 0.308 0.2 –0.8 0.16 –0.46 1.593 0.320 0.1583 1.67 –1.6 –2.8

Electrochemical Series Reaction Br2(aq) + 2 e ⇌ 2 Br– Br2(l) + 2 e ⇌ 2 Br– HBrO + H+ + 2 e ⇌ Br– + H2O HBrO + H+ + e ⇌ 1/2 Br2(aq) + H2O HBrO + H+ + e ⇌ 1/2 Br2(l) + H2O BrO– + H2O + 2 e ⇌ Br– + 2 OH– BrO3– + 6 H+ + 5 e ⇌ 1/2 Br2 + 3 H2O BrO3– + 6 H+ + 6 e ⇌ Br– + 3 H2O BrO3– + 3 H2O + 6 e ⇌ Br– + 6 OH– (CN)2 + 2 H+ + 2 e ⇌ 2 HCN 2 HCNO + 2 H+ + 2 e ⇌ (CN)2 + 2 H2O (CNS)2 + 2 e ⇌ 2 CNS – CO2 + 2 H+ + 2 e ⇌ HCOOH Ca+ + e ⇌ Ca Ca2+ + 2 e ⇌ Ca Ca(OH)2 + 2 e ⇌ Ca + 2 OH– Calomel electrode, 1 molal KCl Calomel electrode, 1 molar KCl (NCE) Calomel electrode, 0.1 molar KCl Calomel electrode, saturated KCl (SCE) Calomel electrode, saturated NaCl (SSCE) Cd2+ + 2 e ⇌ Cd Cd2+ + 2 e ⇌ Cd(Hg) Cd(OH)2 + 2 e ⇌ Cd(Hg) + 2 OH– CdSO4 + 2 e ⇌ Cd + SO42– Cd(OH)42– + 2 e ⇌ Cd + 4 OH– CdO + H2O + 2 e ⇌ Cd + 2 OH– Ce3+ + 3 e ⇌ Ce Ce3+ + 3 e ⇌ Ce(Hg) Ce4+ + e ⇌ Ce3+ CeOH3+ + H+ + e ⇌ Ce3+ + H2O Cf4+ + e ⇌ Cf3+ Cf3+ + e ⇌ Cf2+ Cf3+ + 3 e ⇌ Cf Cf2+ + 2 e ⇌ Cf Cl2(g) + 2 e ⇌ 2 Cl– HClO + H + + e ⇌ 1/2 Cl2 + H2O HClO + H+ + 2 e ⇌ Cl– + H2O ClO– + H2O + 2 e ⇌ Cl– + 2 OH– ClO2 + H+ + e ⇌ HClO2 HClO2 + 2 H+ + 2 e ⇌ HClO + H2O HClO2 + 3 H+ + 3 e ⇌ 1/2 Cl2 + 2 H2O HClO2 + 3 H+ + 4 e ⇌ Cl– + 2 H2O ClO2– + H2O + 2 e ⇌ ClO– + 2 OH– ClO2– + 2 H2O + 4 e ⇌ Cl– + 4 OH– ClO2(aq) + e ⇌ ClO2– ClO3– + 2 H+ + e ⇌ ClO2 + H2O ClO3– + 3 H+ + 2 e ⇌ HClO2 + H2O ClO3– + 6 H+ + 5 e ⇌ 1/2 Cl2 + 3 H2O ClO3– + 6 H+ + 6 e ⇌ Cl– + 3 H2O ClO3– + H2O + 2 e ⇌ ClO2– + 2 OH– ClO3– + 3 H2O + 6 e ⇌ Cl– + 6 OH– ClO4– + 2 H+ + 2 e ⇌ ClO3– H2O ClO4– + 8 H+ + 7 e ⇌ 1/2 Cl2 + 4 H2O ClO4– + 8 H+ + 8 e ⇌ Cl– + 4 H2O ClO4– + H2O + 2 e ⇌ ClO3– + 2 OH– Cm4+ + e ⇌ Cm3+ Cm3+ + 3 e ⇌ Cm Co2+ + 2 e ⇌ Co Co3+ + e ⇌ Co2+

8-21 E°/V 1.0873 1.066 1.331 1.574 1.596 0.761 1.482 1.423 0.61 0.373 0.330 0.77 –0.199 –3.80 –2.868 –3.02 0.2800 0.2801 0.3337 0.2412 0.2360 –0.4030 –0.3521 –0.809 –0.246 –0.658 –0.783 –2.336 –1.4373 1.72 1.715 3.3 –1.6 –1.94 –2.12 1.35827 1.611 1.482 0.81 1.277 1.645 1.628 1.570 0.66 0.76 0.954 1.152 1.214 1.47 1.451 0.33 0.62 1.189 1.39 1.389 0.36 3.0 –2.04 –0.28 1.92

Reaction [Co(NH3)6]3+ + e ⇌ [Co(NH3)6]2+ Co(OH)2 + 2 e ⇌ Co + 2 OH– Co(OH)3 + e ⇌ Co(OH)2 + OH– Cr2+ + 2 e ⇌ Cr Cr3+ + e ⇌ Cr2+ Cr3+ + 3 e ⇌ Cr Cr2O72– + 14 H+ + 6 e ⇌ 2 Cr3+ + 7 H2O CrO2– + 2 H2O + 3 e ⇌ Cr + 4 OH– HCrO4– + 7 H+ + 3 e ⇌ Cr3+ + 4 H2O CrO2 + 4 H+ + e ⇌ Cr3+ + 2H2O Cr(V) + e ⇌ Cr(IV) CrO42– + 4 H2O + 3 e ⇌ Cr(OH)3 + 5 OH– Cr(OH)3 + 3 e ⇌ Cr + 3 OH– Cs+ + e ⇌ Cs Cu+ + e ⇌ Cu Cu2+ + e ⇌ Cu+ Cu2+ + 2 e ⇌ Cu Cu2+ + 2 e ⇌ Cu(Hg) Cu3+ + e ⇌ Cu2+ Cu2O3 + 6 H+ + 2e ⇌ 2Cu2+ + 3 H2O Cu2+ + 2 CN– + e ⇌ [Cu(CN)2]– CuI2– + e ⇌ Cu + 2 I– Cu2O + H2O + 2 e ⇌ 2 Cu + 2 OH– Cu(OH)2 + 2 e ⇌ Cu + 2 OH– 2 Cu(OH)2 + 2 e ⇌ Cu2O + 2 OH– + H2O 2 D+ + 2 e ⇌ D2 Dy2+ + 2 e ⇌ Dy Dy3+ + 3 e ⇌ Dy Dy3+ + e ⇌ Dy2+ Er2+ + 2 e ⇌ Er Er3+ + 3 e ⇌ Er Er3+ + e ⇌ Er2+ Es3+ + e ⇌ Es2+ Es3+ + 3 e ⇌ Es Es2+ + 2 e ⇌ Es Eu2+ + 2 e ⇌ Eu Eu3+ + 3 e ⇌ Eu Eu3+ + e ⇌ Eu2+ F2 + 2 H+ + 2 e ⇌ 2 HF F2 + 2 e ⇌ 2 F– F2O + 2 H+ + 4 e ⇌ H2O + 2 F– Fe2+ + 2 e ⇌ Fe Fe3+ + 3 e ⇌ Fe Fe3+ + e ⇌ Fe2+ 2 HFeO4– + 8 H+ + 6 e ⇌ Fe2O3 + 5 H2O HFeO4– + 4 H+ + 3 e ⇌ FeOOH + 2 H2O HFeO4– + 7 H+ + 3 e ⇌ Fe3+ + 4 H2O Fe2O3 + 4 H+ + 2 e ⇌ 2 FeOH+ + H2O [Fe(CN)6]3– + e ⇌ [Fe(CN)6]4– FeO42– + 8 H+ + 3 e Fe3+ + 4 H2O [Fe(bipy)2]3+ + e ⇌ Fe(bipy)2]2+ [Fe(bipy)3]3+ + e ⇌ Fe(bipy)3]2+ Fe(OH)3 + e ⇌ Fe(OH)2 + OH– [Fe(phen)3]3+ + e ⇌ [Fe(phen)3]2+ [Fe(phen)3]3+ + e ⇌ [Fe(phen)3]2+ (1 molar H2SO4) [Ferricinium]+ + e ⇌ ferrocene Fm3++ e ⇌ Fm2+ Fm3+ + 3 e ⇌ Fm Fm2+ + 2 e ⇌ Fm

E°/V 0.108 –0.73 0.17 –0.913 –0.407 –0.744 1.36 –1.2 1.350 1.48 1.34 –0.13 –1.48 –3.026 0.521 0.153 0.3419 0.345 2.4 2.0 1.103 0.00 –0.360 –0.222 –0.080 –0.013 –2.2 –2.295 –2.6 –2.0 –2.331 –3.0 –1.3 –1.91 –2.23 –2.812 –1.991 –0.36 3.053 2.866 2.153 –0.447 –0.037 0.771 2.09 2.08 2.07 0.16 0.358 2.20 0.78 1.03 –0.56 1.147 1.06 0.400 –1.1 –1.89 –2.30

Electrochemical Series

8-22 Reaction Fr+ + e ⇌ Fr Ga3+ + 3 e ⇌ Ga Ga+ + e ⇌ Ga GaOH2+ + H+ + 3 e ⇌ Ga + H2O H2GaO–3 + H2O + 3 e ⇌ Ga + 4 OH– Gd3+ + 3 e ⇌ Gd Ge2+ + 2 e ⇌ Ge Ge4+ + 4 e ⇌ Ge Ge4+ + 2 e ⇌ Ge2+ GeO2 + 2 H+ + 2 e ⇌ GeO + H2O H2GeO3 + 4 H+ + 4 e ⇌ Ge + 3 H2O 2 H+ + 2 e v H2 H2 + 2 e ⇌ 2 H– HO2 + H+ + e ⇌ H2O2 2 H2O + 2 e ⇌ H2 + 2 OH– H2O2 + 2 H+ + 2 e ⇌ 2 H2O Hf4+ + 4 e ⇌ Hf HfO2+ + 2 H+ + 4 e ⇌ Hf + H2O HfO2 + 4 H+ + 4 e ⇌ Hf + 2 H2O HfO(OH)2 + H2O + 4 e ⇌ Hf + 4 OH– Hg2+ + 2 e ⇌ Hg 2 Hg2+ + 2 e ⇌ Hg22+ Hg22+ + 2 e ⇌ 2 Hg Hg2(ac)2 + 2 e ⇌ 2 Hg + 2(ac)– Hg2Br2 + 2 e ⇌ 2 Hg + 2 Br– Hg2Cl2 + 2 e ⇌ 2 Hg + 2 Cl– Hg2HPO4 + 2 e ⇌ 2 Hg + HPO42– Hg2I2 + 2 e ⇌ 2 Hg + 2 I– Hg2O + H2O + 2 e ⇌ 2 Hg + 2 OH– HgO + H2O + 2 e ⇌ Hg + 2 OH– Hg(OH)2 + 2 H+ + 2 e ⇌ Hg + 2 H2O Hg2SO4 + 2 e ⇌ 2 Hg + SO42– Ho2+ + 2 e ⇌ Ho Ho3+ + 3 e ⇌ Ho Ho3+ + e ⇌ Ho2+ I2 + 2 e ⇌ 2 I– I3– + 2 e ⇌ 3 I– H3IO62– + 2 e ⇌ IO–3 + 3 OH– H5IO6 + H+ + 2 e ⇌ IO3– + 3 H2O 2 HIO + 2 H+ + 2 e ⇌ I2 + 2 H2O HIO + H+ + 2 e ⇌ I– + H2O IO– + H2O + 2 e ⇌ I– + 2 OH– 2 IO3– + 12 H+ + 10 e ⇌ I2 + 6 H2O IO3– + 6 H+ + 6 e ⇌ I– + 3 H2O IO3– + 2 H2O + 4 e ⇌ IO– + 4 OH– IO3– + 3 H2O + 6 e ⇌ IO– + 6 OH– In+ + e ⇌ In In2+ + e ⇌ In+ In3+ + e ⇌ In2+ In3+ + 2 e ⇌ In+ In3+ + 3 e ⇌ In In(OH)3 + 3 e ⇌ In + 3 OH– In(OH)4– + 3 e ⇌ In + 4 OH– In2O3 + 3 H2O + 6 e ⇌ 2 In + 6 OH– Ir3+ + 3 e ⇌ Ir [IrCl6]2– + e ⇌ [IrCl6]3– [IrCl6]3– + 3 e ⇌ Ir + 6 Cl– Ir2O3 + 3 H2O + 6 e ⇌ 2 Ir + 6 OH– K+ + e ⇌ K La3+ + 3 e ⇌ La

E°/V –2.9 –0.549 –0.2 –0.498 –1.219 –2.279 0.24 0.124 0.00 –0.118 –0.182 0.00000 –2.23 1.495 –0.8277 1.776 –1.55 –1.724 –1.505 –2.50 0.851 0.920 0.7973 0.51163 0.13923 0.26808 0.6359 –0.0405 0.123 0.0977 1.034 0.6125 –2.1 –2.33 –2.8 0.5355 0.536 0.7 1.601 1.439 0.987 0.485 1.195 1.085 0.15 0.26 –0.14 –0.40 –0.49 –0.443 –0.3382 –0.99 –1.007 –1.034 1.156 0.8665 0.77 0.098 –2.931 –2.379

Reaction La(OH)3 + 3 e ⇌ La + 3 OH– Li+ + e ⇌ Li Lr3+ + 3 e ⇌ Lr Lu3+ + 3 e ⇌ Lu Md3+ + e ⇌ Md2+ Md3+ + 3 e ⇌ Md Md2+ + 2 e ⇌ Md Mg+ + e ⇌ Mg Mg2+ + 2 e ⇌ Mg Mg(OH)2 + 2 e ⇌ Mg + 2 OH– Mn2+ + 2 e ⇌ Mn Mn3+ + e ⇌ Mn2+ MnO2 + 4 H+ + 2 e ⇌ Mn2+ + 2 H2O MnO4– + e ⇌ MnO42– MnO4– + 4 H+ + 3 e ⇌ MnO2 + 2 H2O MnO4– + 8 H+ + 5 e ⇌ Mn2+ + 4 H2O MnO4– + 2 H2O + 3 e ⇌ MnO2 + 4 OH– MnO42– + 2 H2O + 2 e ⇌ MnO2 + 4 OH– Mn(OH)2 + 2 e ⇌ Mn + 2 OH– Mn(OH)3 + e ⇌ Mn(OH)2 + OH– Mn2O3 + 6 H+ + e ⇌ 2 Mn2+ + 3 H2O Mo3+ + 3 e ⇌ Mo MoO2 + 4 H+ + 4 e ⇌ Mo + 4 H2O H3Mo7O243– + 45 H+ + 42 e ⇌ 7 Mo + 24 H2O MoO3 + 6 H+ + 6 e ⇌ Mo + 3 H2O N2 + 2 H2O + 6 H+ + 6 e ⇌ 2 NH4OH 3 N2 + 2 H+ + 2 e ⇌ 2 HN3 N5+ + 3 H+ + 2 e ⇌ 2 NH4+ N2O + 2 H+ + 2 e ⇌ N2 + H2O H2N2O2 + 2 H+ + 2 e ⇌ N2 + 2 H2O N2O4 + 2 e ⇌ 2 NO2– N2O4 + 2 H+ + 2 e ⇌ 2 NHO2 N2O4 + 4 H+ + 4 e ⇌ 2 NO + 2 H2O 2 NH3OH+ + H+ + 2 e ⇌ N2H5+ + 2 H2O 2 NO + 2 H+ + 2 e ⇌ N2O + H2O 2 NO + H2O + 2 e ⇌ N2O + 2 OH– HNO2 + H+ + e ⇌ NO + H2O 2 HNO2 + 4 H+ + 4 e ⇌ H2N2O2 + 2 H2O 2 HNO2 + 4 H+ + 4 e ⇌ N2O + 3 H2O NO2– + H2O + e ⇌ NO + 2 OH– 2 NO2– + 2 H2O + 4 e ⇌ N2O22– + 4 OH– 2 NO2– + 3 H2O + 4 e ⇌ N2O + 6 OH– NO3– + 3 H+ + 2 e ⇌ HNO2 + H2O NO3– + 4 H+ + 3 e ⇌ NO + 2 H2O 2 NO3– + 4 H+ + 2 e ⇌ N2O4 + 2 H2O NO3– + H2O + 2 e ⇌ NO2– + 2 OH– 2 NO3– + 2 H2O + 2 e ⇌ N2O4 + 4 OH– Na+ + e ⇌ Na Nb3+ + 3 e ⇌ Nb NbO2 + 2 H+ + 2 e ⇌ NbO + H2O NbO2 + 4 H+ + 4 e ⇌ Nb + 2 H2O NbO + 2 H+ + 2 e ⇌ Nb + H2O Nb2O5 + 10 H+ + 10 e ⇌ 2 Nb + 5 H2O Nd3+ + 3 e ⇌ Nd Nd2+ + 2 e ⇌ Nd Nd3+ + e ⇌ Nd2+ Ni2+ + 2 e ⇌ Ni Ni(OH)2 + 2 e ⇌ Ni + 2 OH– NiO2 + 4 H+ + 2 e ⇌ Ni2+ + 2 H2O NiO2 + 2 H2O + 2 e ⇌ Ni(OH)2 + 2 OH–

E°/V –2.90 –3.0401 –1.96 –2.28 –0.1 –1.65 –2.40 –2.70 –2.372 –2.690 –1.185 1.5415 1.224 0.558 1.679 1.507 0.595 0.60 –1.56 0.15 1.485 –0.200 –0.152 0.082 0.075 0.092 –3.09 1.275 1.766 2.65 0.867 1.065 1.035 1.42 1.591 0.76 0.983 0.86 1.297 –0.46 –0.18 0.15 0.934 0.957 0.803 0.01 –0.85 –2.71 –1.099 –0.646 –0.690 –0.733 –0.644 –2.323 –2.1 –2.7 –0.257 –0.72 1.678 –0.490

Electrochemical Series Reaction No3+ + e ⇌ No2+ No3+ + 3 e ⇌ No No2+ + 2 e ⇌ No Np3+ + 3 e ⇌ Np Np4+ + e ⇌ Np3+ NpO2 + H2O + H+ + e ⇌ Np(OH)3 O2 + 2 H+ + 2 e ⇌ H2O2 O2 + 4 H+ + 4 e ⇌ 2 H2O O2 + H2O + 2 e ⇌ HO2– + OH– O2 + 2 H2O + 2 e ⇌ H2O2 + 2 OH– O2 + 2 H2O + 4 e ⇌ 4 OH– O3 + 2 H+ + 2 e ⇌ O2 + H2O O3 + H2O + 2 e ⇌ O2 + 2 OH– O(g) + 2 H+ + 2 e ⇌ H2O OH + e ⇌ OH– HO2– + H2O + 2 e ⇌ 3 OH– OsO4 + 8 H+ + 8 e ⇌ Os + 4 H2O OsO4 + 4 H+ + 4 e ⇌ OsO2 + 2 H2O [Os(bipy)2]3+ + e ⇌ [Os(bipy)2]2+ [Os(bipy)3]3+ + e ⇌ [Os(bipy)3]2+ P(red) + 3 H+ + 3 e ⇌ PH3(g) P(white) + 3 H+ + 3 e ⇌ PH3(g) P + 3 H2O + 3 e ⇌ PH3(g) + 3 OH– H2P2– + e ⇌ P + 2 OH– H3PO2 + H+ + e ⇌ P + 2 H2O H3PO3 + 2 H+ + 2 e ⇌ H3PO2 + H2O H3PO3 + 3 H+ + 3 e ⇌ P + 3 H2O HPO32– + 2 H2O + 2 e ⇌ H2PO2– + 3 OH– HPO32– + 2 H2O + 3 e ⇌ P + 5 OH– H3PO4 + 2 H+ + 2 e ⇌ H3PO3 + H2O PO43– + 2 H2O + 2 e ⇌ HPO32– + 3 OH– Pa3+ + 3 e ⇌ Pa Pa4+ + 4 e ⇌ Pa Pa4+ + e ⇌ Pa3+ Pb2+ + 2 e ⇌ Pb Pb2+ + 2 e ⇌ Pb(Hg) PbBr2 + 2 e ⇌ Pb + 2 Br– PbCl2 + 2 e ⇌ Pb + 2 Cl– PbF2 + 2 e ⇌ Pb + 2 F– PbHPO4 + 2 e ⇌ Pb + HPO42– PbI2 + 2 e ⇌ Pb + 2 I– PbO + H2O + 2 e ⇌ Pb + 2 OH– PbO2 + 4 H+ + 2 e ⇌ Pb2+ + 2 H2O HPbO2– + H2O + 2 e ⇌ Pb + 3 OH– PbO2 + H2O + 2 e ⇌ PbO + 2 OH– PbO2 + SO42– + 4 H+ + 2 e ⇌ PbSO4 + 2 H2O PbSO4 + 2 e ⇌ Pb + SO42– PbSO4 + 2 e ⇌ Pb(Hg) + SO42– Pd2+ + 2 e ⇌ Pd [PdCl4]2– + 2 e ⇌ Pd + 4 Cl– [PdCl6]2– + 2 e ⇌ [PdCl4]2– + 2 Cl– Pd(OH)2 + 2 e ⇌ Pd + 2 OH– Pm2+ + 2 e ⇌ Pm Pm3+ + 3 e ⇌ Pm Pm3+ + e ⇌ Pm2+ Po4+ + 2 e ⇌ Po2+ Po4+ + 4 e ⇌ Po Pr4+ + e ⇌ Pr3+ Pr2+ + 2 e ⇌ Pr Pr3+ + 3 e ⇌ Pr

8-23 E°/V 1.4 –1.20 –2.50 –1.856 0.147 –0.962 0.695 1.229 –0.076 –0.146 0.401 2.076 1.24 2.421 2.02 0.878 0.838 1.02 0.81 0.80 –0.111 –0.063 –0.87 –1.82 –0.508 –0.499 –0.454 –1.65 –1.71 –0.276 –1.05 –1.34 –1.49 –1.9 –0.1262 –0.1205 –0.284 –0.2675 –0.3444 –0.465 –0.365 –0.580 1.455 –0.537 0.247 1.6913 –0.3588 –0.3505 0.951 0.591 1.288 0.07 –2.2 –2.30 –2.6 0.9 0.76 3.2 –2.0 –2.353

Reaction Pr3+ + e ⇌ Pr2+ Pt2+ + 2 e ⇌ Pt [PtCl4]2– + 2 e ⇌ Pt + 4 Cl– [PtCl6]2– + 2 e ⇌ [PtCl4]2– + 2 Cl– Pt(OH)2 + 2 e ⇌ Pt + 2 OH– PtO3 + 2 H+ + 2 e ⇌ PtO2 + H2O PtO3 + 4 H+ + 2 e ⇌ Pt(OH)22+ + H2O PtOH+ + H+ + 2 e ⇌ Pt + H2O PtO2 + 2 H+ + 2 e ⇌ PtO + H2O PtO2 + 4 H+ + 4 e ⇌ Pt + 2 H2O Pu3+ + 3 e ⇌ Pu Pu4+ + e ⇌ Pu3+ Pu5+ + e ⇌ Pu4+ PuO2(OH)2 + 2 H+ + 2 e ⇌ Pu(OH)4 PuO2(OH)2 + H+ + e ⇌ PuO2OH + H2O Ra2+ + 2 e ⇌ Ra Rb+ + e ⇌ Rb Re3+ + 3 e ⇌ Re ReO4– + 4 H+ + 3 e ⇌ ReO2 + 2 H2O ReO2 + 4 H+ + 4 e ⇌ Re + 2 H2O ReO4– + 2 H+ + e ⇌ ReO3 + H2O ReO4– + 4 H2O + 7 e ⇌ Re + 8 OH– ReO4– + 8 H+ + 7 e ⇀ Re + 4 H2O Rh+ + e ⇌ Rh Rh3+ + 3 e ⇌ Rh [RhCl6]3– + 3 e ⇌ Rh + 6 Cl– RhOH2+ + H+ + 3 e ⇌ Rh + H2O Ru2+ + 2 e ⇌ Ru Ru3+ + e ⇌ Ru2+ RuO2 + 4 H+ + 2 e ⇌ Ru2+ + 2 H2O RuO4– + e ⇌ RuO42– RuO4 + e ⇌ RuO4– RuO4 + 6 H+ + 4 e ⇌ Ru(OH)22+ + 2 H2O RuO4 + 8 H+ + 8 e ⇌ Ru + 4 H2O [Ru(bipy)3)3+ + e– ⇌ [Ru(bipy)3]2+ [Ru(H2O)6]3+ + e– ⇌ [Ru(H2O)6]2+ [Ru(NH3)6]3+ + e– ⇌ [Ru(NH3)6]2+ [Ru(en)3]3+ + e – ⇌ [Ru(en)3]2+ [Ru(CN)6]3– + e– ⇌ [Ru(CN)6]4– S + 2 e ⇌ S2– S + 2H+ + 2 e ⇌ H2S(aq) S + H2O + 2 e ⇌ SH– + OH– 2 S + 2 e ⇌ S22– S2O62– + 4 H+ + 2 e ⇌ 2 H2SO3 S2O82– + 2 e ⇌ 2 SO42– S2O82– + 2 H+ + 2 e ⇌ 2 HSO4– S4O62– + 2 e ⇌ 2 S2O32– 2 H2SO3 + H+ + 2 e ⇌ HS2O4– + 2 H2O H2SO3 + 4 H+ + 4 e ⇌ S + 3 H2O 2 SO32– + 2 H2O + 2 e ⇌ S2O42– + 4 OH– 2 SO32– + 3 H2O + 4 e ⇌ S2O32– + 6 OH– SO42– + 4 H+ + 2 e ⇌ H2SO3 + H2O 2 SO42– + 4 H+ + 2 e ⇌ S2O62– + H2O SO42– + H2O + 2 e ⇌ SO32– + 2 OH– Sb + 3 H+ + 3 e ⇌ SbH3 Sb2O3 + 6 H+ + 6 e ⇌ 2 Sb + 3 H2O Sb2O5 (senarmontite) + 4 H+ + 4 e ⇌ Sb2O3 + 2 H2O Sb2O5 (valentinite) + 4 H+ + 4 e ⇌ Sb2O3 + 2 H2O

E°/V –3.1 1.18 0.755 0.68 0.14 1.7 1.5 1.2 1.01 1.00 –2.031 1.006 1.099 1.325 1.062 –2.8 –2.98 0.300 0.510 0.2513 0.768 –0.584 0.368 0.600 0.758 0.431 0.83 0.455 0.2487 1.120 0.59 1.00 1.40 1.038 1.24 0.23 0.10 0.210 0.86 –0.47627 0.142 –0.478 –0.42836 0.564 2.010 2.123 0.08 –0.056 0.449 –1.12 –0.571 0.172 –0.22 –0.93 –0.510 0.152 0.671 0.649

Electrochemical Series

8-24 Reaction Sb2O5 + 6 H+ + 4 e ⇌ 2 SbO+ + 3 H2O SbO+ + 2 H+ + 3 e ⇌ Sb + 2 H2O SbO2– + 2 H2O + 3 e ⇌ Sb + 4 OH– SbO3– + H2O + 2 e ⇌ SbO2– + 2 OH– Sc3+ + 3 e ⇌ Sc Se + 2 e ⇌ Se2– Se + 2 H+ + 2 e ⇌ H2Se(aq) H2SeO3 + 4 H+ + 4 e ⇌ Se + 3 H2O Se + 2 H+ + 2 e ⇌ H2Se SeO32– + 3 H2O + 4 e ⇌ Se + 6 OH– SeO42– + 4 H+ + 2 e ⇌ H2SeO3 + H2O SeO42– + H2O + 2 e ⇌ SeO32– + 2 OH– SiF62– + 4 e ⇌ Si + 6 F– SiO + 2 H+ + 2 e ⇌ Si + H2O SiO2 (quartz) + 4 H+ + 4 e ⇌ Si + 2 H2O SiO32– + 3 H2O + 4 e ⇌ Si + 6 OH– Sm3+ + e ⇌ Sm2+ Sm3+ + 3 e ⇌ Sm Sm2+ + 2 e ⇌ Sm Sn2+ + 2 e ⇌ Sn Sn4+ + 2 e ⇀ Sn2+ Sn(OH)3+ + 3 H+ + 2 e ⇌ Sn2+ + 3 H2O SnO2 + 4 H+ + 2 e– ⇌ Sn2+ + 2 H2O SnO2 + 4 H+ + 4 e ⇌ Sn + 2 H2O SnO2 + 3 H+ + 2 e ⇌ SnOH+ + H2O SnO2 + 2 H2O + 4 e ⇌ Sn + 4 OH– HSnO2– + H2O + 2 e ⇌ Sn + 3 OH– Sn(OH)62– + 2 e ⇌ HSnO2– + 3 OH– + H2O Sr+ + e ⇌ Sr Sr2+ + 2 e ⇌ Sr Sr2+ + 2 e ⇌ Sr(Hg) Sr(OH)2 + 2 e ⇌ Sr + 2 OH– Ta2O5 + 10 H+ + 10 e ⇌ 2 Ta + 5 H2O Ta3+ + 3 e ⇌ Ta Tc2+ + 2 e ⇌ Tc TcO4– + 4 H+ + 3 e ⇌ TcO2 + 2 H2O Tc3+ + e ⇌ Tc2+ TcO4– + 8 H+ + 7 e ⇌ Tc + 4 H2O Tb4+ + e ⇌ Tb3+ Tb3+ + 3 e ⇌ Tb Te + 2 e ⇌ Te2– Te + 2 H+ + 2 e ⇌ H2Te Te4+ + 4 e ⇌ Te TeO2 + 4 H+ + 4 e ⇌ Te + 2 H2O TeO32– + 3 H2O + 4 e ⇌ Te + 6 OH– TeO4– + 8 H+ + 7 e ⇌ Te + 4 H2O H6TeO6 + 2 H+ + 2 e ⇌ TeO2 + 4 H2O Th4+ + 4 e ⇌ Th ThO2 + 4 H+ + 4 e ⇌ Th + 2 H2O Th(OH)4 + 4 e ⇌ Th + 4 OH– Ti2+ + 2 e ⇌ Ti Ti3+ + e ⇌ Ti2+ TiO2 + 4 H+ + 2 e ⇌ Ti2+ + 2 H2O Ti3+ + 3 e ⇌ Ti TiOH3+ + H+ + e ⇌ Ti3+ + H2O

E°/V 0.581 0.212 –0.66 –0.59 –2.077 –0.924 –0.399 0.74 –0.082 –0.366 1.151 0.05 –1.24 –0.8 0.857 –1.697 –1.55 –2.304 –2.68 –0.1375 0.151 0.142 –0.094 –0.117 –0.194 –0.945 –0.909 –0.93 –4.10 –2.899 –1.793 –2.88 –0.750 –0.6 0.400 0.782 0.3 0.472 3.1 –2.28 –1.143 –0.793 0.568 0.593 –0.57 0.472 1.02 –1.899 –1.789 –2.48 –1.630 –0.9 –0.502 –1.37 –0.055

Reaction Tl+ + e ⇌ Tl Tl+ + e ⇌ Tl(Hg) Tl3+ + 2 e ⇌ Tl+ Tl3+ + 3 e ⇌ Tl TlBr + e ⇌ Tl + Br– TlCl + e ⇌ Tl + Cl– TlI + e ⇌ Tl + I– Tl2O3 + 3 H2O + 4 e ⇌ 2 Tl+ + 6 OH– TlOH + e ⇌ Tl + OH– Tl(OH)3 + 2 e ⇌ TlOH + 2 OH– Tl2SO4 + 2 e ⇌ Tl + SO42– Tm3+ + e ⇌ Tm2+ Tm3+ + 3 e ⇌ Tm Tm2+ + 2 e ⇌ Tm U3+ + 3 e ⇌ U U4+ + e ⇌ U3+ UO2+ + 4 H+ + e ⇌ U4+ + 2 H2O UO22+ + e ⇌ UO+2 UO22+ + 4 H+ + 2 e ⇌ U4+ + 2 H2O UO22+ + 4 H+ + 6 e ⇌ U + 2 H2O V2+ + 2 e ⇌ V V3+ + e ⇌ V2+ VO2+ + 2 H+ + e ⇌ V3+ + H2O VO2+ + 2 H+ + e ⇌ VO2+ + H2O V2O5 + 6 H+ + 2 e ⇌ 2 VO2+ + 3 H2O V2O5 + 10 H+ + 10 e ⇌ 2 V + 5 H2O V(OH)4+ + 2 H+ + e ⇌ VO2+ + 3 H2O V(OH)4+ + 4 H+ + 5 e ⇌ V + 4 H2O [V(phen)3]3+ + e ⇌ [V(phen)3]2+ W3+ + 3 e ⇌ W W2O5 + 2 H+ + 2 e ⇌ 2 WO2 + H2O WO2 + 4 H+ + 4 e ⇌ W + 2 H2O WO3 + 6 H+ + 6 e ⇌ W + 3 H2O WO3 + 2 H+ + 2 e ⇌ WO2 + H2O 2 WO3 + 2 H+ + 2 e ⇌ W2O5 + H2O H4XeO6 + 2 H+ + 2 e ⇌ XeO3 + 3 H2O XeO3 + 6 H+ + 6 e ⇌ Xe + 3 H2O XeF + e ⇌ Xe + F– Y3+ + 3 e ⇌ Y Yb3+ + e ⇌ Yb2+ Yb3+ + 3 e ⇌ Yb Yb2+ + 2 e ⇌ Yb Zn2+ + 2 e ⇌ Zn Zn2+ + 2 e ⇌ Zn(Hg) ZnO22– + 2 H2O + 2 e ⇌ Zn + 4 OH– ZnSO4 · 7 H2O + 2 e = Zn(Hg) + SO42– + 7 H2O (Saturated ZnSO4) ZnOH+ + H+ + 2 e ⇌ Zn + H2O Zn(OH)42– + 2 e ⇌ Zn + 4 OH– Zn(OH)2 + 2 e ⇌ Zn + 2 OH– ZnO + H2O + 2 e ⇌ Zn + 2 OH– ZrO2 + 4 H+ + 4 e ⇌ Zr + 2 H2O ZrO(OH)2 + H2O + 4 e ⇌ Zr + 4 OH– Zr4+ + 4 e ⇌ Zr

E°/V –0.336 –0.3338 1.252 0.741 –0.658 –0.5568 –0.752 0.02 –0.34 –0.05 –0.4360 –2.2 –2.319 –2.4 –1.798 –0.607 0.612 0.062 0.327 –1.444 –1.175 –0.255 0.337 0.991 0.957 –0.242 1.00 –0.254 0.14 0.1 –0.031 –0.119 –0.090 0.036 –0.029 2.42 2.10 3.4 –2.372 –1.05 –2.19 –2.76 –0.7618 –0.7628 –1.215 –0.7993 –0.497 –1.199 –1.249 –1.260 –1.553 –2.36 –1.45

Electrochemical Series

8-25

TABLE 2. Reduction Reactions Having E° Values More Positive than That of the Standard Hydrogen Electrode Reaction 2 H+ + 2 e ⇌ H2 CuI2– + e ⇌ Cu + 2 I– Ge4+ + 2 e ⇌ Ge2+ NO3– + H2O + 2 e ⇌ NO2– + 2 OH– Tl2O3 + 3 H2O + 4 e ⇌ 2 Tl+ + 6 OH– SeO42– + H2O + 2 e ⇌ SeO32– + 2 OH– WO3 + 2 H+ + 2 e ⇌ WO2 + H2O UO22+ + e = UO2+ Pd(OH)2 + 2 e ⇌ Pd + 2 OH– AgBr + e ⇌ Ag + Br– MoO3 + 6 H+ + 6 e ⇌ Mo + 3 H2O S4O62– + 2 e ⇌ 2 S2O32– H3Mo7O243– + 45 H+ + 42 e ⇌ 7 Mo + 24 H2O AgSCN + e ⇌ Ag + SCN– N2 + 2 H2O + 6 H+ + 6 e ⇌ 2 NH4OH HgO + H2O + 2 e ⇌ Hg + 2 OH– Ir2O3 + 3 H2O + 6 e ⇌ 2 Ir + 6 OH– 2 NO + 2 e ⇌ N2O22– [Ru(NH3)6]3+ + e ⇌ [Ru(NH3)6]2+ W3+ + 3 e ⇌ W [Co(NH3)6]3+ + e ⇌ [Co(NH3)6]2+ Hg2O + H2O + 2 e ⇌ 2 Hg + 2 OH– Ge4+ + 4 e ⇌ Ge Hg2Br2 + 2 e ⇌ 2 Hg + 2 Br– Pt(OH)2 + 2 e ⇌ Pt + 2 OH– [V(phen)3]3+ + e ⇌ [V(phen)3]2+ S + 2H+ + 2 e ⇌ H2S(aq) Sn(OH)3+ + 3 H+ + 2 e ⇌ Sn2+ + 3 H2O Np4+ + e ⇌ Np3+ Ag4[Fe(CN)6] + 4 e ⇌ 4 Ag + [Fe(CN)6]4– IO3– + 2 H2O + 4 e ⇌ IO– + 4 OH– Mn(OH)3 + e ⇌ Mn(OH)2 + OH– 2 NO2– + 3 H2O + 4 e ⇌ N2O + 6 OH– Sn4+ + 2 e ⇌ Sn2+ Sb2O3 + 6 H+ + 6 e ⇌ 2 Sb + 3 H2O Cu2+ + e ⇌ Cu+ BiOCl + 2 H+ + 3 e ⇌ Bi + Cl– + H2O BiCl4– + 3 e ⇌ Bi + 4 Cl– Fe2O3 + 4 H+ + 2 e ⇌ 2 FeOH+ + H2O Co(OH)3 + e ⇌ Co(OH)2 + OH– SO42– + 4 H+ + 2 e ⇌ H2SO3 + H2O Bi3+ + 2 e ⇌ Bi+ [Ru(en)3]3+ + e ⇌ [Ru(en)3]2+ SbO+ + 2 H+ + 3 e ⇌ Sb + 2 H2O AgCl + e ⇌ Ag + Cl– [Ru(H2O)6]3+ + e ⇌ [Ru(H2O)6]2+ As2O3 + 6 H+ + 6 e ⇌ 2 As + 3 H2O Calomel electrode, saturated NaCl (SSCE) Ge2+ + 2 e ⇌ Ge Ru3+ + e ⇌ Ru2+ Calomel electrode, saturated KCl PbO2 + H2O + 2 e ⇌ PbO + 2 OH– HAsO2 + 3 H+ + 3 e ⇌ As + 2 H2O Ru3+ + e ⇀ Ru2+ ReO2 + 4 H+ + 4 e ⇌ Re + 2 H2O IO3– + 3 H2O + 6 e ⇌ I– + OH–

E°/V 0.00000 0.00 0.00 0.01 0.02 0.05 0.036 0.062 0.07 0.07133 0.075 0.08 0.082 0.8951 0.092 0.0977 0.098 0.10 0.10 0.1 0.108 0.123 0.124 0.13923 0.14 0.14 0.142 0.142 0.147 0.1478 0.15 0.15 0.15 0.151 0.152 0.153 0.1583 0.16 0.16 0.17 0.172 0.2 0.210 0.212 0.22233 0.23 0.234 0.2360 0.24 0.24 0.2412 0.247 0.248 0.2487 0.2513 0.26

Reaction Hg2Cl2 + 2 e ⇌ 2 Hg + 2 Cl– Calomel electrode, 1 molal KCl Calomel electrode, 1 molar KCl (NCE) At2 + 2 e ⇌ 2 At– Re3+ + 3 e ⇌ Re Tc3+ + e ⇌ Tc2+ Bi3+ + 3 e ⇌ Bi BiO+ + 2 H+ + 3 e ⇌ Bi + H2O

UO22+ + 4 H+ + 2 e ⇌ U4+ + 2 H2O ClO3– + H2O + 2 e ⇌ ClO2– + 2 OH– 2 HCNO + 2 H+ + 2 e ⇌ (CN)2 + 2 H2O Calomel electrode, 0.1 molar KCl VO2+ + 2 H+ + e ⇌ V3+ + H2O Cu2+ + 2 e ⇌ Cu Ag2O + H2O + 2 e ⇌ 2 Ag + 2 OH– Cu2+ + 2 e ⇌ Cu(Hg) AgIO3 + e ⇌ Ag + IO3– [Fe(CN)6]3– + e ⇌ [Fe(CN)6]4– ClO4– + H2O + 2 e ⇌ ClO–3 + 2 OH– Ag2SeO3 + 2 e ⇌ 2 Ag + SeO32– ReO4– + 8 H+ + 7 e ⇌ Re + 4 H2O (CN)2 + 2 H+ + 2 e ⇌ 2 HCN [Ferricinium]+ + e ⇌ ferrocene Tc2+ + 2 e ⇌ Tc O2 + 2 H2O + 4 e ⇌ 4 OH– AgOCN + e ⇌ Ag + OCN– [RhCl6]3– + 3 e ⇌ Rh + 6 Cl– Ag2CrO4 + 2 e ⇌ 2 Ag + CrO42– H2SO3 + 4 H+ + 4 e ⇌ S + 3 H2O Ru2+ + 2 e ⇌ Ru Ag2MoO4 + 2 e ⇌ 2 Ag + MoO42– Ag2C2O4 + 2 e ⇌ 2 Ag + C2O42– Ag2WO4 + 2 e ⇌ 2 Ag + WO42– Ag2CO3 + 2 e ⇌ 2 Ag + CO32– TcO4– + 8 H+ + 7 e ⇌ Tc + 4 H2O TeO4– + 8 H+ + 7 e ⇌ Te + 4 H2O IO– + H2O + 2 e ⇌ I– + 2 OH– NiO2 + 2 H2O + 2 e ⇌ Ni(OH)2 + 2 OH– Bi+ + e ⇌ Bi ReO4– + 4 H+ + 3 e ⇌ ReO2 + 2 H2O Hg2(ac)2 + 2 e ⇌ 2 Hg + 2(ac)– Cu+ + e ⇌ Cu I2 + 2 e ⇌ 2 I– I3– + 2 e ⇌ 3 I– AgBrO3 + e ⇌ Ag + BrO3– MnO4– + e ⇌ MnO4– H3AsO4 + 2 H+ + 2 e ⇌ HAsO2 + 2 H2O S2O62– + 4 H+ + 2 e ⇌ 2 H2SO3 AgNO2 + e ⇌ Ag + NO2– Te4+ + 4 e ⇌ Te Sb2O5 + 6 H+ + 4 e ⇌ 2 SbO+ + 3 H2O RuO4– + e ⇌ RuO42– [PdCl4]2– + 2 e ⇌ Pd + 4 Cl– TeO2 + 4 H+ + 4 e ⇌ Te + 2 H2O MnO4– + 2 H2O + 3 e ⇌ MnO2 + 4 OH– Rh2+ + 2 e ⇌ Rh

E°/V 0.26808 0.2800 0.2801 0.3 0.300 0.3 0.308 0.320 0.327 0.33 0.330 0.3337 0.337 0.3419 0.342 0.345 0.354 0.358 0.36 0.3629 0.368 0.373 0.400 0.400 0.401 0.41 0.431 0.4470 0.449 0.455 0.4573 0.4647 0.4660 0.47 0.472 0.472 0.485 0.490 0.5 0.510 0.51163 0.521 0.5355 0.536 0.546 0.558 0.560 0.564 0.564 0.568 0.581 0.59 0.591 0.593 0.595 0.600

Electrochemical Series

8-26 Reaction Rh+ + e ⇌ Rh MnO42– + 2 H2O + 2 e ⇌ MnO2 + 4 OH– 2 AgO + H2O + 2 e ⇌ Ag2O + 2 OH– BrO3– + 3 H2O + 6 e ⇌ Br– + 6 OH– UO2+ + 4 H+ + e ⇌ U4+ + 2 H2O Hg2SO4 + 2 e ⇌ 2 Hg + SO42– ClO3– + 3 H2O + 6 e ⇌ Cl– + 6 OH– Hg2HPO4 + 2 e ⇌ 2 Hg + HPO42– Ag(ac) + e ⇌ Ag + (ac)– Sb2O5(valentinite) + 4 H+ + 4 e ⇌ Sb2O3 + 2 H2O Ag2SO4 + 2 e ⇌ 2 Ag + SO42– ClO2– + H2O + 2 e ⇌ ClO– + 2 OH– Sb2O5(senarmontite) + 4 H+ + 4 e ⇌ Sb2O5 + 2 H2O [PtCl6]2– + 2 e ⇌ [PtCl4]2– + 2 Cl– O2 + 2 H+ + 2 e ⇌ H2O2 p–benzoquinone + 2 H+ + 2 e ⇌⇌ hydroquinone H3IO62– + 2 e ⇌ IO3– + 3 OH– Ag2O3+ H2O + 2 e ⇌ 2 AgO + 2 OH– Tl3+ + 3 e ⇌ Tl [PtCl4]2– + 2 e ⇌ Pt + 4 Cl– Rh3+ + 3 e ⇌ Rh ClO2– + 2 H2O + 4 e ⇌ Cl– + 4 OH– 2 NO + H2O + 2 e ⇌ N2O + 2 OH– Po4+ + 4 e ⇌ Po BrO– + H2O + 2 e ⇌ Br– + 2 OH– ReO4– + 2 H+ +e ⇌ ReO3 + H2O (CNS)2 + 2 e ⇌ 2 CNS – [IrCl6]3– + 3 e ⇌ Ir + 6 Cl– Fe3+ + e ⇌ Fe2+ AgF + e ⇌ Ag + F– [Fe(bipy)2]3+ + e ⇌ [Fe(bipy)2]2+ TcO4– + 4 H+ + 3 e ⇌ TcO2 + 2 H2O Hg22+ + 2 e ⇌ 2 Hg Ag+ + e ⇌ Ag [Os(bipy)3]3+ + e ⇌ [Os(bipy)3]2+ 2 NO3– + 4 H+ + 2 e ⇌ N2O4 + 2 H2O [Os(bipy)2]3+ + e ⇌ [Os(bipy)2]2+ RhOH2+ + H + 3 e ⇌ Rh + H2O OsO4 + 8 H+ + 8 e ⇌ Os + 4 H2O ClO– + H2O + 2 e ⇌ Cl– + 2 OH– Hg2+ + 2 e ⇌ Hg AuBr4– + 3 e ⇌ Au + 4 Br– SiO2(quartz) + 4 H+ + 4 e ⇌ Si + 2 H2O 2 HNO2 + 4 H+ + 4 e ⇌ H2N2O2 + H2O [Ru(CN)6]3– + e– ⇌ [Ru(CN)6]4– [IrCl6]2– + e ⇌ [IrCl6]3– N2O4 + 2 e ⇌ 2 NO2– HO2– + H2O + 2 e ⇌ 3 OH– Po4+ + 2 e ⇌ Po2+ 2 Hg2+ + 2 e ⇌ Hg22+ NO3– + 3 H+ + 2 e ⇌ HNO2 + H2O Pd2+ + 2 e ⇌ Pd ClO2(aq) + e ⇌ ClO2– NO3– + 4 H+ + 3 e ⇌ NO + 2 H2O V2O5 + 6 H+ + 2 e ⇌ 2 VO2+ + 3 H2O AuBr2– + e ⇌ Au + 2 Br– HNO2 + H+ + e ⇌ NO + H2O

E°/V 0.600 0.60 0.607 0.61 0.612 0.6125 0.62 0.6359 0.643 0.649 0.654 0.66 0.671 0.68 0.695 0.6992 0.7 0.739 0.741 0.755 0.758 0.76 0.76 0.76 0.761 0.768 0.77 0.77 0.771 0.779 0.78 0.782 0.7973 0.7996 0.80 0.803 0.81 0.83 0.838 0.841 0.851 0.854 0.857 0.86 0.86 0.8665 0.867 0.878 0.9 0.920 0.934 0.951 0.954 0.957 0.957 0.959 0.983

Reaction HIO + H+ + 2 e ⇌ I– + H2O VO2+ + 2 H+ + e ⇌ VO2+ + H2O PtO2 + 4 H+ + 4 e ⇌ Pt + 2 H2O RuO4 + e ⇌ RuO4– V(OH)4+ + 2 H+ + e ⇌ VO2+ + 3 H2O AuCl4– + 3 e ⇌ Au + 4 Cl– Pu4+ + e ⇌ Pu3+ PtO2 + 2 H+ + 2 e ⇌ PtO + H2O OsO4 + 4 H + 4 e ⇌ OsO2 + 2 H2O H6TeO6 + 2 H+ + 2 e ⇌ TeO2 + 4 H2O [Fe(bipy)3]3+ + e ⇌ [Fe(bipy)3]2+ Hg(OH)2 + 2 H+ + 2 e ⇌ Hg + 2 H2O N2O4 + 4 H+ + 4 e ⇌ 2 NO + 2 H2O RuO4 + 8 H+ + 8 e ⇌ Ru + 4H2O [Fe(phen)3]3+ + e ⇌ [Fe(phen)3]2+ (1 molar H2SO4) PuO2(OH)2 + H+ + e ⇌ PuO2OH + H2O N2O4 + 2 H+ + 2 e ⇌ 2 HNO2 Br2(l) + 2 e ⇌ 2Br– IO3– + 6 H+ + 6 e ⇌ I– + 3 H2O Br2(aq) + 2 e ⇌ 2Br– Pu5+ + e ⇌ Pu4+ Cu2+ + 2 CN– + e ⇌ [Cu(CN)2]–

RuO2 + 4 H+ + 2 e ⇌ Ru2+ + 2 H2O [Fe(phen)3]3+ + e ⇌⇀ [Fe(phen)3]2+ SeO42– + 4 H+ + 2 e ⇌ H2SeO3 + H2O ClO3– + 2 H+ + e ⇌ ClO2 + H2O Ir3+ + 3 e ⇀ Ir Pt2+ + 2 e ⇌ Pt ClO4– + 2 H+ + 2 e ⇌ ClO3– + H2O 2 IO3– + 12 H+ + 10 e ⇌ I2 + 6 H2O PtOH+ + H+ + 2 e ⇌ Pt + H2O ClO3– + 3 H+ + 2 e ⇌ HClO2 + H2O MnO2 + 4 H+ + 2 e ⇌ Mn2+ + 2 H2O O2 + 4 H+ + 4 e ⇌ 2 H2O O3 + H2O + 2 e ⇌ O2 + 2 OH– [Ru(bipy)3]3+ + e ⇌ [Ru(bipy)3]2+ Tl3+ + 2 e ⇌ Tl+ N2H5+ + 3 H+ + 2 e ⇌ 2 NH4+ ClO2 + H+ + e ⇌ HClO2 [PdCl6]2– + 2 e ⇌ [PdCl4]2– + 2 Cl– 2 HNO2 + 4 H+ + 4 e ⇌ N2O + 3 H2O AuOH2+ + H+ + 2 e ⇌ Au+ + H2O PuO2(OH)2 + 2 H– + 2 e ⇌ Pu(OH)4 HBrO + H+ + 2 e ⇌ Br– + H2O Cr(V) + e ⇌ Cr(IV) HCrO4– + 7 H+ + 3 e ⇌ Cr3+ + 4 H2O Cl2(g) + 2 e ⇌ 2Cl– Cr2O72– + 14 H+ + 6 e ⇌ 2 Cr3+ + 7 H2O ClO4– + 8 H+ + 8 e ⇌ Cl– + 4 H2O ClO4– + 8 H+ + 7 e ⇌ 1/2 Cl2 + 4 H2O No3+ + e ⇌ No2+ RuO4 + 6 H+ + 4 e ⇌ Ru(OH)22+ + 2 H2O Au3+ + 2 e ⇌ Au+ 2 NH3OH+ + H+ + 2 e ⇌ N2H5+ + 2 H2O BrO3– + 6 H+ + 6 e ⇌ Br– + 3 H2O 2 HIO + 2 H+ + 2 e ⇌ I2 + 2 H2O Au(OH)3 + 3 H+ + 3 e ⇌ Au– + 3 H2O

E°/V 0.987 0.991 1.00 1.00 1.00 1.002 1.006 1.01 1.02 1.02 1.03 1.034 1.035 1.038 1.06 1.062 1.065 1.066 1.085 1.0873 1.099 1.103 1.120 1.147 1.151 1.152 1.156 1.18 1.189 1.195 1.2 1.214 1.224 1.229 1.24 1.24 1.252 1.275 1.277 1.288 1.297 1.32 1.325 1.331 1.34 1.350 1.35827 1.36 1.389 1.39 1.4 1.40 1.401 1.42 1.423 1.439 1.45

Electrochemical Series Reaction 3IO3– + 6 H+ + 6 e ⇌ Cl– + 3 H2O PbO2 +4 H+ + 2 e ⇌ Pb2+ + 2 H2O ClO3– + 6 H+ + 5 e ⇌ 1/2 Cl2 + 3 H2O CrO2 + 4 H+ + e ⇌ Cr3+ + 2 H2O BrO3– + 6 H+ + 5 e ⇌ 1/2 Br2 + 3 H2O HClO + H+ + 2 e ⇌ Cl– + H2O Mn2O3 + 6 H+ + e ⇌ 2 Mn2+ + 3 H2O HO2 + H+ + e ⇌ H2O2 Au3+ + 3 e ⇌ Au PtO3 + 4 H+ + 2 e ⇌ Pt(OH)22+ + H2O MnO4– + 8 H+ + 5 e ⇌ Mn2+ + 4 H2O Mn3+ + e ⇌ Mn2– HClO2 + 3 H+ + 4 e ⇌ Cl– + 2 H2O HBrO + H+ + e ⇌ 1/2 Br2(aq) + H2O 2 NO + 2 H+ + 2 e ⇌ N2O + H2O Bi2O4 + 4 H+ + 2 e ⇌ 2 BiO+ + 2 H2O HBrO + H+ + e ⇌ 1/2 Br2(l) + H2O H5IO6 + H+ + 2 e ⇌ IO3– + 3 H2O HClO + H+ + e ⇌ 1/2 Cl2 + H2O HClO2 + 3 H+ + 3 e ⇌ 1/2 Cl2 + 2 H2O HClO2 + 2 H+ + 2 e ⇌ HClO + H2O Bk4+ + e ⇌ Bk3+ NiO2 + 4 H+ + 2 e ⇌ Ni2+ + 2 H2O MnO4– + 4 H+ + 3 e ⇀ MnO2 + 2 H2O PbO2 + SO42– + 4 H+ + 2 e ⇌ PbSO4 + 2 H2O Au+ + e ⇌ Au PtO3 + 2 H+ + 2 e ⇌ PtO2 + H2O CeOH3+ + H+ + e ⇌ Ce3+ + H2O Ce4+ + e ⇌ Ce3+ N2O + 2 H+ + 2 e⇌ N2 + H2O H2O2 + 2 H+ + 2 e ⇌ 2 H2O

8-27 E°/V 1.451 1.455 1.47 1.48 1.482 1.482 1.485 1.495 1.498 1.5 1.507 1.5415 1.570 1.574 1.591 1.593 1.596 1.601 1.611 1.628 1.645 1.67 1.678 1.679 1.6913 1.692 1.7 1.715 1.72 1.766 1.776

Reaction Ag3+ + e ⇌ Ag2+ Au2+ + e– ⇌ Au+ Ag2O2 + 4 H+ + e ⇌ 2 Ag + 2 H2O Co3+ + e ⇌ Co2–(2 molar H2SO4) Ag3+ + 2 e ⇌ Ag+ Co3+ + e ⇌ Co2+ Ag2+ + e ⇌ Ag+ Cu2O3 + 6 H+ + 2 e ⇌ 2 Cu2+ + 3 H2O S2O82– + 2 e ⇌ 2 SO42– OH + e ⇌ OH– HFeO4– + 7 H+ + 3 e ⇌ Fe3+ + 4 H2O O3 + 2 H+ + 2 e ⇌ O2 + H2O HFeO4– + 4 H+ + 3 e ⇌ FeOOH + 2 H2O 2 HFeO4– + 8 H+ + 6 e ⇌ Fe2O3 + 5 H2O XeO3 + 6 H+ + 6 e ⇌ Xe + 3 H2O S2O82– + 2 H+ + 2 e ⇌ 2 HSO4– F2O + 2 H+ + 4 e ⇌ H2O + 2 F– FeO42– + 8 H+ + 3 e ⇌ Fe3+ + 4 H2O Cu3+ + e ⇌ Cu2+ H4XeO6 + 2 H+ + 2 e ⇌ XeO3 + 3 H2O O(g) + 2 H+ + 2 e ⇌ H2O Am4+ + e ⇌ Am3+ H2N2O2 + 2 H+ + 2 e ⇌ N2 + 2 H2O F2 + 2 e ⇌ 2 F– Cm4+ + e ⇌ Cm3+ F2 + 2 H+ + 2 e ⇌ 2 HF Tb4+ + e ⇌ Tb3+ Pr4+ + e ⇌ Pr3+ Cf4+ + e ⇌ Cf3+ XeF + e ⇌ Xe + F–

E°/V 1.8 1.8 1.802 1.83 1.9 1.92 1.980 2.0 2.010 2.02 2.07 2.076 2.08 2.09 2.10 2.123 2.153 2.20 2.4 2.42 2.421 2.60 2.65 2.866 3.0 3.053 3.1 3.2 3.3 3.4

TABLE 3. Reduction Reactions Having E° Values More Negative than That of the Standard Hydrogen Electrode Reaction 2 H+ + 2 e ⇌ H2 2 D+ + 2 e ⇌ D2 AgCN + e ⇌ Ag + CN– 2 WO3 + 2 H+ + 2 e ⇌ W2O5 + H2O W2O5 + 2 H+ + 2 e ⇌ 2 WO2 + H2O Ag2S + 2 H+ + 2 e ⇌ 2 Ag + H2S Fe3+ + 3 e ⇌ Fe Hg2I2 + 2 e ⇌ 2 Hg + 2 I– Tl(OH)3 + 2 e ⇌ TlOH + 2 OH– TiOH3+ + H+ + e ⇌ Ti3+ + H2O 2 H2SO3 + H+ + 2 e ⇌ HS2O4– + 2 H2O P(white) + 3 H+ + 3 e ⇌ PH3(g) O2 + H2O + 2 e ⇌ HO2– + OH– 2 Cu(OH)2 + 2 e ⇌ Cu2O + 2 OH– + H2O Se + 2 H+ + 2 e ⇌ H2Se WO3 + 6 H+ + 6 e ⇌ W + 3 H2O SnO2 + 4 H+ + 2 e ⇌ Sn2+ + 2 H2O Md3+ + e ⇌ Md2+ P(red) + 3 H+ + 3 e ⇌ PH3(g) SnO2 + 4 H+ + 4 e ⇌ Sn + 2 H2O GeO2 + 2 H+ + 2 e ⇌ GeO + H2O

E°/V 0.00000 –0.013 –0.017 –0.029 –0.031 –0.0366 –0.037 –0.0405 –0.05 –0.055 –0.056 –0.063 –0.076 –0.080 –0.082 –0.090 –0.094 –0.1 –0.111 –0.117 –0.118

Reaction WO2 + 4 H+ + 4 e ⇌ W + 2 H2O Pb2+ + 2 e ⇌ Pb(Hg) Pb2+ + 2 e ⇌ Pb CrO42– + 4 H2O + 3 e ⇌ Cr(OH)3 + 5 OH– Sn2– + 2 e ⇌ Sn In+ + e ⇌ In O2 + 2 H2O + 2 e ⇌ H2O2 + 2 OH– MoO2 + 4 H+ + 4 e ⇌ Mo + 4 H2O AgI + e ⇌ Ag + I– 2 NO2– + 2 H2O + 4 e ⇌ N2O22– + 4 OH– H2GeO3 + 4 H+ + 4 e ⇌ Ge + 3 H2O SnO2 + 3 H+ + 2 e ⇌ SnOH+ + H2O CO2 + 2 H+ + 2 e ⇌ HCOOH Mo3+ + 3 e ⇌ Mo Ga+ + e ⇌ Ga 2 SO22– + 4 H+ + 2 e ⇌ S2O62– + H2O Cu(OH)2 + 2 e ⇌ Cu + 2 OH– V2O5 + 10 H+ + 10 e ⇌ 2 V + 5 H2O CdSO4 + 2 e ⇌ Cd + SO42– V(OH)4+ + 4 H+ + 5 e ⇌ V + 4 H2O V3+ + e ⇌ V2+

E°/V –0.119 –0.1205 –0.1262 –0.13 –0.1375 –0.14 –0.146 –0.152 –0.15224 –0.18 –0.182 –0.194 –0.199 –0.200 –0.2 –0.22 –0.222 –0.242 –0.246 –0.254 –0.255

Electrochemical Series

8-28 Reaction Ni2+ + 2 e ⇌ Ni PbCl2 + 2 e ⇌ Pb + 2 Cl– H3PO4 + 2 H+ + 2 e ⇌ H3PO3 + H2O Co2+ + 2 e ⇌ Co PbBr2 + 2 e ⇌ Pb + 2 Br– Tl+ + e ⇌ Tl(Hg) Tl+ + e ⇌ Tl In3+ + 3 e ⇌ In TlOH + e ⇌ Tl + OH– PbF2 + 2 e ⇌ Pb + 2 F– PbSO4 + 2 e ⇌ Pb(Hg) + SO42– Cd2+ + 2 e ⇌ Cd(Hg) PbSO4 + 2 e ⇌ Pb + SO42– Cu2O + H2O + 2 e ⇌ 2 Cu + 2 OH– Eu3+ + e ⇌ Eu2+ PbI2 + 2 e ⇌ Pb + 2 I– SeO32– + 3 H2O + 4 e ⇌ Se + 6 OH– Se + 2 H+ + 2 e ⇌ H2Se(aq) In2+ + e ⇌ In+ Cd2+ + 2 e ⇌ Cd Cr3+ + e ⇌ Cr2+ 2 S + 2 e ⇌ S22– Tl2SO4 + 2 e ⇌ Tl + SO42– In3+ + 2 e ⇌ In+ Fe2+ + 2 e ⇌ Fe H3PO3 + 3 H+ + 3 e ⇌ P + 3 H2O Bi2O3 + 3 H2O + 6 e ⇌ 2 Bi + 6 OH– NO2– + H2O + e ⇌ NO + 2 OH PbHPO4 + 2 e ⇌ Pb + HPO42– S + 2 e ⇌ S2– S + H2O + 2 e ⇌ HS – + OH– B(OH)3 + 7 H+ + 8 e ⇌ BH4– + 3 H2O In3+ + e ⇌ In2+ ZnOH+ + H+ + 2 e ⇌ Zn + H2O GaOH2+ + H+ + 3 e ⇌ Ga + H2O H3PO3 + 2 H+ + 2 e ⇌ H3PO2 + H2O TiO2 + 4 H+ + 2 e ⇌ Ti2+ + 2 H2O H3PO2 + H+ + e ⇌ P + 2 H2O Sb + 3 H+ + 3 e ⇌ SbH3 HPbO2– + H2O + 2 e ⇌ Pb + 3 OH– Ga3+ + 3 e ⇌ Ga TlCl + e ⇌ Tl + Cl– Fe(OH)3 + e ⇌ Fe(OH)2 + OH– TeO32– + 3 H2O + 4 e ⇌ Te + 6 OH– 2 SO32– + 3 H2O + 4 e ⇌ S2O32– + 6 OH– PbO + H2O + 2 e ⇌ Pb + 2 OH– ReO2– + 4 H2O + 7 e ⇌ Re + 8 OH– SbO3– + H2O + 2 e ⇌ SbO2– + 2 OH– Ta3+ + 3 e ⇌ Ta U4+ + e ⇌ U3+ As + 3 H+ + 3 e ⇌ AsH3 Nb2O5 + 10 H+ + 10 e ⇌ 2 Nb + 5 H2O NbO2 + 2 H+ + 2 e ⇌ NbO + H2O Cd(OH)42– + 2 e ⇌ Cd + 4 OH– TlBr + e ⇌ Tl + Br– SbO2– + 2 H2O + 3 e ⇌ Sb + 4 OH– AsO2– + 2 H2O + 3 e ⇌ As + 4 OH–

E°/V –0.257 –0.2675 –0.276 –0.28 –0.284 –0.3338 –0.336 –0.3382 –0.34 –0.3444 –0.3505 –0.3521 –0.3588 –0.360 –0.36 –0.365 –0.366 –0.399 –0.40 –0.4030 –0.407 –0.42836 –0.4360 –0.443 –0.447 –0.454 –0.46 –0.46 –0.465 –0.47627 –0.478 –0.481 –0.49 –0.497 –0.498 –0.499 –0.502 –0.508 –0.510 –0.537 –0.549 –0.5568 –0.56 –0.57 –0.571 –0.580 –0.584 –0.59 –0.6 –0.607 –0.608 –0.644 –0.646 –0.658 –0.658 –0.66 –0.68

Reaction NbO2 + 4 H+ + 4 e ⇌ Nb + 2 H2O Ag2S + 2 e ⇌ 2 Ag + S2– AsO43– + 2 H2O + 2 e ⇌ AsO2– + 4 OH– Ni(OH)2 + 2 e ⇌ Ni + 2 OH– Co(OH)2 + 2 e ⇌ Co + 2 OH– NbO + 2 H+ + 2 e ⇌ Nb + H2O H2SeO3 + 4 H+ + 4 e ⇌ Se + 3 H2O Cr3+ + 3 e ⇌ Cr Ta2O5 + 10 H+ + 10 e ⇌ 2 Ta + 5 H2O TlI + e ⇌ Tl + I– Zn2+ + 2 e ⇌ Zn Zn2+ + 2 e ⇌ Zn(Hg) CdO + H2O + 2 e ⇌ Cd + 2 OH– Te + 2 H+ + 2 e ⇌ H2Te ZnSO4.7H2O + 2 e ⇌ Zn(Hg) + SO42– + 7 H2O (Saturated ZnSO4) Bi + 3 H+ + 3 e ⇌ BiH3 SiO + 2 H+ + 2 e ⇌ Si + H2O Cd(OH)2 + 2 e ⇌ Cd(Hg) + 2 OH– 2 H2O + 2 e ⇌ H2 + 2 OH– 2 NO–3 + 2 H2O + 2 e ⇌ N2O4 + 4 OH– H3BO3 + 3 H+ + 3 e ⇌ B + 3 H2O P + 3 H2O + 3 e ⇌ PH3(g) + 3 OH– Ti3+ + e ⇌ Ti2+ HSnO2– + H2O + 2 e ⇌ Sn + 3 OH– Cr2+ + 2 e ⇌ Cr Se + 2 e ⇌ Se2– SO42– + H2O + 2 e ⇌ SO32– + 2 OH– Sn(OH)62– + 2 e ⇌ HSnO2– + 3 OH– + H2O SnO2 + 2 H2O + 4 e ⇌ Sn + 4 OH– In(OH)3 + 3 e ⇌ In + 3 OH– NpO2 + H2O + H+ + e ⇌ Np(OH)3 In(OH)4– + 3 e ⇌ In + 4 OH– In2O3 + 3 H2O + 6 e ⇌ 2 In + 6 OH– PO43– + 2 H2O + 2 e ⇌ HPO32– + 3 OH– Yb3+ + e ⇌ Yb2+ Nb3+ + 3 e ⇌ Nb Fm3+ + e ⇌ Fm2+ 2 SO32– + 2 H2O + 2 e ⇌ S2O42– + 4 OH– Te + 2 e ⇌ Te2– V2+ + 2 e ⇌ V Mn2+ + 2 e ⇌ Mn Zn(OH)42– + 2 e ⇌ Zn + 4 OH– CrO2 + 2 H2O + 3 e ⇌ Cr + 4 OH– No3+ + 3 e ⇌ No ZnO2– + 2 H2O + 2 e ⇌ Zn + 4 OH– H2GaO3– + H2O + 3 e ⇌ Ga + 4 OH– H2BO3– + 5 H2O + 8 e ⇌ BH4– + 8 OH– SiF62– + 4 e ⇌ Si + 6 F– Zn(OH)2 + 2 e ⇌ Zn + 2 OH– ZnO + H2O + 2 e ⇌ Zn + 2 OH– Es3+ + e ⇌ Es2+ Pa3+ + 3 e ⇌ Pa Ti3+ + 3 e ⇌ Ti Ce3+ + 3 e ⇌ Ce(Hg) UO22+ + 4 H+ + 6 e ⇌ U + 2 H2O Zr4+ + 4 e ⇌ Zr

E°/V –0.690 –0.691 –0.71 –0.72 –0.73 –0.733 –0.74 –0.744 –0.750 –0.752 –0.7618 –0.7628 –0.783 –0.793 –0.7993 –0.8 –0.8 –0.809 –0.8277 –0.85 –0.8698 –0.87 –0.9 –0.909 –0.913 –0.924 –0.93 –0.93 –0.945 –0.99 –0.962 –1.007 –1.034 –1.05 –1.05 –1.099 –1.1 –1.12 –1.143 –1.175 –1.185 –1.199 –1.2 –1.20 –1.215 –1.219 –1.24 –1.24 –1.249 –1.260 –1.3 –1.34 –1.37 –1.4373 –1.444 –1.45

Electrochemical Series Reaction Cr(OH)3 + 3 e ⇌ Cr + 3 OH– Pa4+ + 4 e ⇌ Pa HfO2 + 4 H+ + 4 e ⇌ Hf + 2 H2O Hf4+ + 4 e ⇌ Hf Sm3+ + e ⇌ Sm2+ ZrO2 + 4 H+ + 4 e ⇌ Zr + 2 H2O Mn(OH)2 + 2 e ⇌ Mn + 2 OH– Ba2+ + 2 e ⇌ Ba(Hg) Bk2+ + 2 e ⇌ Bk Cf3+ + e ⇌ Cf2+ Ti2+ + 2 e ⇌ Ti Md3+ + 3 e ⇌ Md HPO32– + 2 H2O + 2 e ⇌ H2PO2– + 3 OH– Al3+ + 3 e ⇌ Al SiO32– + H2O + 4 e ⇌ Si + 6 OH– HPO32– + 2 H2O + 3 e ⇌ P + 5 OH– HfO2+ + 2 H+ + 4 e ⇌ Hf + H2O ThO2 + 4 H+ + 4 e ⇌ Th + 2 H2O H2BO3– + H2O + 3 e ⇌ B + 4 OH– Sr2+ + 2 e ⇌ Sr(Hg) U3+ + 3 e ⇌ U H2PO–2 + e ⇌ P + 2 OH– Be2+ + 2 e ⇌ Be Np3+ + 3 e ⇌ Np Fm3+ + 3 e ⇌ Fm Th4+ + 4 e ⇌ Th Am2+ + 2 e ⇌ Am Pa4+ + e ⇌ Pa3+ Es3+ + 3 e ⇌ Es Cf3+ + 3 e ⇌ Cf Lr3+ + 3 e ⇌ Lr Eu3+ + 3 e ⇌ Eu Er2+ + 2 e ⇌ Er Pr2+ + 2 e ⇌ Pr Pu3+ + 3 e ⇌ Pu Cm3+ + 3 e ⇌ Cm Am3+ + 3 e ⇌ Am AlF63– + 3 e ⇌ Al + 6 F– Sc3+ + 3 e ⇌ Sc Ho2+ + 2 e ⇌ Ho Nd2+ + 2 e ⇌ Nd Cf2+ + 2 e ⇌ Cf Yb3+ + 3 e ⇌ Yb Ac3+ + 3 e ⇌ Ac Dy2+ + 2 e ⇌ Dy Tm3+ + e ⇌ Tm2+ Pm2+ + 2 e ⇌ Pm Es2+ + 2 e ⇌ Es H2 + 2 e ⇌ 2 H– Gd3+ + 3 e ⇌ Gd Tb3+ + 3 e ⇌ Tb Lu3+ + 3 e ⇌ Lu Dy3+ + 3 e ⇌ Dy

8-29 E°/V –1.48 –1.49 –1.505 –1.55 –1.55 –1.553 –1.56 –1.570 –1.6 –1.6 –1.630 –1.65 –1.65 –1.662 –1.697 –1.71 –1.724 –1.789 –1.79 –1.793 –1.798 –1.82 –1.847 –1.856 –1.89 –1.899 –1.9 –1.9 –1.91 –1.94 –1.96 –1.991 –2.0 –2.0 –2.031 –2.04 –2.048 –2.069 –2.077 –2.1 –2.1 –2.12 –2.19 –2.20 –2.2 –2.2 –2.2 –2.23 –2.23 –2.279 –2.28 –2.28 –2.295

Reaction Am3+ + e ⇌ Am2+ Fm2+ + 2 e ⇌ Fm Pm3+ + 3 e ⇌ Pm Sm3+ + 3 e ⇌ Sm Al(OH)3 + 3 e ⇌ Al + 3 OH– Tm3+ + 3 e ⇌ Tm Nd3+ + 3 e ⇌ Nd Al(OH)– + 3 e ⇌ Al + 4 OH– H2AlO3– + H2O + 3 e ⇌ Al + 4 OH– Ho3+ + 3 e ⇌ Ho Er3+ + 3 e ⇌ Er Ce3+ + 3 e ⇌ Ce Pr3+ + 3 e ⇌ Pr ZrO(OH)2 + H2O + 4 e ⇌ Zr + 4 OH– Mg2+ + 2 e ⇌ Mg Y3+ + 3 e ⇌ Y La3+ + 3 e ⇌ La Tm2+ + 2 e ⇌ Tm Md2+ + 2 e ⇌ Md Th(OH)4 + 4 e ⇌ Th + 4 OH– HfO(OH)2 + H2O + 4 e ⇌ Hf + 4 OH– No2+ + 2 e ⇌ No Dy3+ + e ⇌ Dy2+ Pm3+ + e ⇌ Pm2+ Be2O32– + 3 H2O + 4 e ⇌ 2 Be + 6 OH– Sm2+ + 2 e ⇌ Sm Mg(OH)2 + 2 e ⇌ Mg + 2 OH– Nd3+ + e ⇌ Nd2+ Mg+ + e ⇌ Mg Na+ + e ⇌ Na Yb2+ + 2 e ⇌ Yb Bk3+ + e ⇌ Bk2+ Ho3+ + e ⇌ Ho2+ Ra2+ + 2 e ⇌ Ra Eu2+ + 2 e ⇌ Eu Ca2+ + 2 e ⇌ Ca Sr(OH)2 + 2 e ⇌ Sr + 2 OH– Sr2+ + 2 e ⇌ Sr Fr+ + e ⇌ Fr La(OH)3 + 3 e ⇌ La + 3 OH– Ba2+ + 2 e ⇌ Ba K+ + e ⇌ K Rb+ + e ⇌ Rb Ba(OH)2 + 2 e ⇌ Ba + 2 OH– Er3+ + e ⇌ Er2+ Ca(OH)2 + 2 e ⇌ Ca + 2 OH– Cs+ + e ⇌ Cs Li+ + e ⇌ Li 3 N2 + 2 H+ + 2 e ⇌ 2 HN3 Pr3+ + e ⇌ Pr2+ Ca+ + e ⇌ Ca Sr+ + e ⇌ Sr

E°/V –2.3 –2.30 –2.30 –2.304 –2.31 –2.319 –2.323 –2.328 –2.33 –2.33 –2.331 –2.336 –2.353 –2.36 –2.372 –2.372 –2.379 –2.4 –2.40 –2.48 –2.50 –2.50 –2.6 –2.6 –2.63 –2.68 –2.690 –2.7 –2.70 –2.71 –2.76 –2.8 –2.8 –2.8 –2.812 –2.868 –2.88 –2.899 –2.9 –2.90 –2.912 –2.931 –2.98 –2.99 –3.0 –3.02 –3.026 –3.0401 –3.09 –3.1 –3.80 –4.10