16.15: Polarographic Half-Wave Potentials
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The following table provides E1/2 values for selected reduction reactions. Values are from Dean, J. A. Analytical Chemistry Handbook, McGraw-Hill: New York, 1995.
Element | E1/2 (volts vs. SCE) | Matrix |
---|---|---|
Al3+(aq)+3e−−⇀↽−Al(s) | –0.5 | 0.2 M acetate (pH 4.5–4.7) |
Cd2+(aq)+2e−−⇀↽−Cd(s) | –0.6 |
0.1 M KCl 0.050 M H2SO4 1 M HNO3 |
Cr3+(aq)+3e−−⇀↽−Cr(s) |
–0.35 (+3⟶+2) –1.70 (+2⟶0) |
1 M NH4Cl plus 1 M NH3 1 M NH4+/NH3 buffer (pH 8–9) |
Co3+(aq)+3e−−⇀↽−Co(s) |
–0.5 (+3⟶+2) –1.3 (+2⟶0) |
1 M NH4Cl plus 1 M NH3 |
Co2+(aq)+2e−−⇀↽−Co(s) | –1.03 |
1 M KSCN |
Cu2+(aq)+2e−−⇀↽−Cu(s) |
0.04 –0.22 |
0.1 M KSCN 0.1 M NH4ClO4 1 M Na2SO4 0.5 M potassium citrate (pH 7.5) |
Fe3+(aq)+3e−−⇀↽−Fe(s) |
–0.17 (+3⟶+2) –1.52 (+2⟶0) |
0.5 M sodium tartrate (pH 5.8) |
Fe3+(aq)+e−−⇀↽−Fe2+(aq) | –0.27 | 0.2 M Na2C2O4 (pH < 7.9) |
Pb2+(aq)+2e−−⇀↽−Pb(s) |
–0.405 –0.435 |
1 M HNO3 1 M KCl |
Mn2+(aq)+2e−−⇀↽−Mn(s) | –1.65 | 1 M NH4Cl plus 1 M NH3 |
Ni2+(aq)+2e−−⇀↽−Ni(s) |
–0.70 –1.09 |
1 M KSCN 1 M NH4Cl plus 1 M NH3 |
Zn2+(aq)+2e−−⇀↽−Zn(s) |
–0.995 –1.33 |
0.1 M KCl 1 M NH4Cl plus 1 M NH3 |