Current Control: Voltammetry and Polarography Principles Quiz

Voltammetry involves applying a varying potential to a working electrode and measuring the resulting current as a function of that potential.

Polarography is a subclass of voltammetry that specifically uses a Dropping Mercury Electrode (DME) as the working electrode, which provides a continuously renewed surface.

This is true. Under conditions where mass transport is limited only by diffusion, the plateau current in a polarogram is used for quantitative analysis of the analyte concentration.

The Ilkovic Equation is the fundamental mathematical relationship in polarography that describes the limiting diffusion current at a Dropping Mercury Electrode.

The half wave potential is a characteristic property of the electroactive species. It is the potential at which the current is exactly half of the limiting diffusion current.

Oxygen is easily reduced at many electrode surfaces, creating two large waves that can overlap and interfere with the peaks of interest from the analyte.

This is false. The Reference Electrode measures the potential. The Counter (or Auxiliary) Electrode completes the circuit and carries the bulk of the current to protect the reference electrode.

Supporting electrolytes increase the conductivity of the solution, ensuring that the analyte moves to the electrode by diffusion rather than by electrical attraction (migration).

Cyclic, Stripping, and Pulse methods are standard electrochemical techniques. Combustion is a thermal analysis technique, not a voltammetric one.

For a perfectly reversible redox couple, the peak separation is approximately 59 millivolts divided by the number of electrons. Larger separations indicate slower electron transfer kinetics.

This is true. The analyte is first plated onto the electrode at a constant potential and then stripped off by scanning the potential, allowing for detection at parts per billion levels.

While the DME provides a fresh surface and high overpotential for hydrogen, the toxicity of mercury and the mechanical issues with fine glass capillaries are significant drawbacks.

Higher scan rates and larger electrode areas generally increase the peak current. Atmospheric pressure has negligible effects on standard solution phase voltammetry.

Even without an analyte, a small current flows as the electrode surface acts like a capacitor, building up a double layer of ions. This is known as the charging or capacitive current.

This is true. The working electrode is the site of the electrochemical interest, where the potential is controlled to drive the specific redox reaction being studied.