Question

List the advantages and disadvantages of the mercury film electrode compared with platinum or carbon electrodes.

Short answer

The advantage of DME is that Hg forms soluble mixtures with many metals so their reduction potential is reduced.

The disadvantage of DME is that mercury is easily oxidized and becomes toxic.

Step-by-step solution

Step1. Given information

Dropping mercury electrode is an electrode in which gravity results in the formation of successive droplets of $\mathrm{Hg}$ at the end of a capillary tube, each drop providing a fresh electrode surface.

Platinum electrodes are in some ways the opposite of $\mathrm{AgCl}$ electrodes. Platinum is biocompatible and therefore highly suitable for invasive electrodes and implants.

The carbon electrode is not a metal, technically a semi-metal, but conducts electricity well under the right conditions to be useful as a conductor in certain circumstances.

Step2. Advantage and disadvantage of mercury film electrode

Advantages of dropping mercury electrodes:

• The advantages of the poly urethane-tipped plunger system are that the full-size drop is formed quickly and current measurements can be delayed until the surface area is constant, with classical dropping mercury electrodes experiencing large current fluctuations. have to do.
• Relatively large negative potential range.
• A fresh metal surface is easily formed by the production of only one new drop. The ability to easily obtain a fresh surface is important because the currents measured in voltammetry are highly sensitive to cleanliness and freedom from irregularities.
• Many metal ions on the surface of the mercury electrode are reversibly reduced to the amalgam.

Disadvantages of dropping mercury electrodes:

• It is poisonous so care must be taken in handling it.
• The surface area of a drop of mercury is never constant.
• The applied voltage produces a change in the surface tension and hence a change in the drop size.
• Mercury has limited applications in the analysis of more positive potentials.