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Standard Reduction Potentials



Ox + ne1– Red ℰ° (V)
K1+(aq) + e1– equilibrium arrow K(s) –2.92
Na1+(aq) + e1– equilibrium arrow Na(s) –2.71
Mg2+(aq) + 2 e1– equilibrium arrow Mg(s) –2.36
Al3+(aq) + 3 e1– equilibrium arrow Al(s) –1.66
2 H2O + 2 e1– equilibrium arrow H2(g)+ 2 OH1–(aq) –0.83
Zn2+(aq) + 2 e1– equilibrium arrow Zn (s) –0.76
Cr3+(aq) + 3 e1– equilibrium arrow Cr(s) –0.74
Fe2+(aq) + 2 e1– equilibrium arrow Fe(s) –0.44
2 H2O + 2 e1– equilibrium arrow H2(g)+ 2 OH1–(aq) –0.41*
PbSO4(s) + 2 e1– equilibrium arrow Pb(s) + SO42–(aq) –0.36
Ni2+(aq) + 2 e1– equilibrium arrow Ni(s) –0.23
Sn2+(aq) + 2 e1– equilibrium arrow Sn(s) –0.14
Pb2+(aq)+ 2 e1– equilibrium arrow Pb(s) –0.13
2 H1+(aq) + 2 e 1– equilibrium arrow H2(g) 0.00
Cu2+(aq) + 2 e1– equilibrium arrow Cu(s) +0.34
O2(g) + 2 H2O + 4 e1– equilibrium arrow 4 OH1–(aq) +0.40
I2(s) + 2 e1– equilibrium arrow 2 I1–(aq) +0.54
Fe3+(aq) + e1– equilibrium arrow Fe2+(aq) +0.77
Ag1+(aq) + e1– equilibrium arrow Ag(s) +0.80
O2(g) + 4 H1+(aq) + 4 e1– equilibrium arrow 2 H2O +0.82*
NO31–(aq) + 4 H1+(aq) + 3 e1– equilibrium arrow NO(g) + 2 H2O +0.96
Br2(l) + 2 e1– equilibrium arrow 2 Br1–(aq) +1.09
O2(g) + 4 H1+(aq) + 4 e1– equilibrium arrow 2 H2O +1.23
Cr2O72–(aq) + 14 H1+(aq) + 6 e1– equilibrium arrow 2 Cr3+(aq) + 7 H2O +1.33
Cl2(g) + 2 e1– equilibrium arrow 2 Cl1–(aq) +1.36
MnO41–(aq) + 8 H1+(aq) + 5 e1– equilibrium arrow Mn2+(aq) + 4 H2O +1.51
PbO2(s) + 4 H1+(aq) + SO42–(aq) + 2 e1– equilibrium arrow PbSO4(s) + 2 H2O +1.69
F2(g) + 2 e1– equilibrium arrow 2 F1–(aq) +2.87
Standard Reduction Potentials at 25 °C in Volts
* The half-cell potentials for the O2/H2O and the H2O/H2 systems are for pure water and are not for standard reduction potentials where [OH1-] and [H1+] = 1.0 M.