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  Section: Practical Skills in Chemistry » Instrumental techniques
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Cyclic voltammetry

Instrumental techniques
  Basic spectroscopy
    Introduction to spectroscopy
    UV Ivisible spectrophotometry
    Fluorescence spectrophotometry
    Phosphorescence and luminescence
    Atomic spectroscopy
  Atomic spectroscopy
    Atomic Absorption Spectroscopy
    Atomic Emission Spectroscopy
    Inductively coupled plasma
    Decomposition techniques for solid inorganic samples
  Infrared spectroscopy
  Nuclear magnetic resonance spectrometry
    1H-NMR spectra
    13C-NMR spectra
  Mass spectrometry
    Interfacing mass spectrometry
  Chromatography ~ introduction
    The chromatogram
  Gas and liquid chromatography
    Gas chromatography
    Liquid chromatography
    High-performance liquid chromatography
    Interpreting chromatograms
    Optimizing chromatographic separations
    Quantitative analysis
    The supporting medium
    Capillary electrophoresis
    Capillary zone electrophoresis (CZE)
    Micellar electrokinetic chromatography (MEKC)
  Electroanalytical techniques
    Potentiometry and ion-selective electrodes
    Voltammetric methods
    Oxygen electrodes
    Coulometric methods
    Cyclic voltammetry
  Radioactive isotopes and their uses
    Radioactive decay
    Measuring radioactivity
    Chemical applications for radioactive isotopes
    Working practices when using radioactive isotopes
  Thermal analysis

The technique provides qualitative information about electrochemical reactions, e.g. the redox behaviour of compounds and the kinetics of electron transfer reactions. In practice, a triangular potential waveform is applied linearly to the working electrode in a unstirred solution. After a few seconds, the ramp is reversed and the potential is returned to its initial value. The process may be repeated several times. The resulting plot of current versus potential is termed a cyclic voltammogram. Fig. 34.9 shows a typical cyclic voltammogram for a reversible redox couple after a single potential cycle. It is assumed that the oxidized form, O, is the only species present at the start. Therefore, the first scan is towards the (more) negative direction, commencing at a value were no reduction occurs. As the applied potential approaches the characteristic for the redox process, a catholic current starts to increase, up to a maximum. After exceeding the potential at which the reduction process takes place, the direction of the potential current is reversed. During this stage, reduced molecules R, generated during the initial process, are reoxidized back to O, resulting in an anodic peak.
A typical cyclic voltammogram for a reversible
Fig. 34.9 A typical cyclic voltammogram for a reversible
O + ne ↔ R redox process.


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