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10.15: 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 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


This page titled 10.15: Polarographic Half-Wave Potentials is shared under a CC BY-NC-SA 4.0 license and was authored, remixed, and/or curated by David Harvey.

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