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P4: Polarographic Half-Wave Potentials

  • Page ID
    6651
  • 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+ + 3e ⇋ Al(s) –0.5 0.2 M acetate (pH 4.5–4.7)
    Cd2+ + 2e ⇋ Cd(s) –0.60 0.1 M KCl
    0.05 M H2SO4
    1 M HNO3
    Cr3+ + 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+ + 3e ⇋ Co(s) –0.5 (+3 → +2)
    –1.3 (+2 → 0)
    1 M NH4Cl plus 1 M NH3
    Co2+ + 2e ⇋ Co(s) –1.03 1 M KSCN

    Cu2+ + 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+ + 3e ⇋ Fe(s) –0.17 (+3 → +2)
    –1.52 (+2 → 0)
    0.5 M sodium tartrate (pH 5.8)

    Fe3+ + e ⇋ Fe2+

    –0.27 0.2 M Na2C2O4 (pH < 7.9)
    Pb2+ + 2e ⇋ Pb(s) –0.405
    –0.435
    1 M HNO3
    1 M KCl
    Mn2+ + 2e ⇋ Mn(s) –1.65 1 M NH4Cl plus 1 M NH3
    Ni2+ + 2e ⇋ Ni(s)

    –0.70
    –1.09

    1 M KSCN
    1 M NH4Cl plus 1 M NH3

    Zn2+ + 2e ⇋ Zn(s)

    –0.995
    –1.33
    0.1 M KCl
    1 M NH4Cl plus 1 M NH3