16.15: Polarographic Half-Wave Potentials
- Page ID
- 220812
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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 | \(E_{1/2}\) (volts vs. SCE) | Matrix |
|---|---|---|
| \(\ce{Al^{3+}}(aq) + \ce{3 e-} \ce{<=>} \ce{Al}(s)\) | –0.5 | 0.2 M acetate (pH 4.5–4.7) |
| \(\ce{Cd^{2+}}(aq) + \ce{2 e-} \ce{<=>} \ce{Cd}(s)\) | –0.6 |
0.1 M KCl 0.050 M H2SO4 1 M HNO3 |
| \(\ce{Cr^{3+}}(aq) + \ce{3 e-} \ce{<=>} \ce{Cr}(s)\) |
–0.35 \((+3 \ce{->} +2)\) –1.70 \((+2 \ce{->} 0)\) |
1 M NH4Cl plus 1 M NH3 1 M NH4+/NH3 buffer (pH 8–9) |
| \(\ce{Co^{3+}}(aq)+ \ce{3 e-} \ce{<=>} \ce{Co}(s)\) |
–0.5 \((+3 \ce{->} +2)\) –1.3 \((+2 \ce{->} 0)\) |
1 M NH4Cl plus 1 M NH3 |
| \(\ce{Co^{2+}}(aq) + \ce{2 e-} \ce{<=>} \ce{Co}(s)\) | –1.03 |
1 M KSCN |
| \(\ce{Cu^{2+}}(aq) + \ce{2 e-} \ce{<=>} \ce{Cu}(s)\) |
0.04
–0.22 |
0.1 M KSCN 0.1 M NH4ClO4 1 M Na2SO4 0.5 M potassium citrate (pH 7.5) |
| \(\ce{Fe^{3+}}(aq) + \ce{3 e-} \ce{<=>} \ce{Fe}(s)\) |
–0.17 \((+3 \ce{->} +2)\) –1.52 \((+2 \ce{->} 0)\) |
0.5 M sodium tartrate (pH 5.8) |
| \(\ce{Fe^{3+}}(aq) + \ce{e-} \ce{<=>} \ce{Fe^{2+}}(aq)\) | –0.27 | 0.2 M Na2C2O4 (pH < 7.9) |
| \(\ce{Pb^{2+}}(aq) + \ce{2 e-} \ce{<=>} \ce{Pb}(s)\) |
–0.405 –0.435 |
1 M HNO3 1 M KCl |
| \(\ce{Mn^{2+}}(aq) + \ce{2 e-} \ce{<=>} \ce{Mn}(s)\) | –1.65 | 1 M NH4Cl plus 1 M NH3 |
| \(\ce{Ni^{2+}}(aq) + \ce{2 e-} \ce{<=>} \ce{Ni}(s)\) |
–0.70 –1.09 |
1 M KSCN 1 M NH4Cl plus 1 M NH3 |
| \(\ce{Zn^{2+}}(aq) + \ce{2 e-} \ce{<=>} \ce{Zn}(s)\) |
–0.995 –1.33 |
0.1 M KCl 1 M NH4Cl plus 1 M NH3 |