- Mercury form amalgam with most metals.
- Mercury has a high hydrogen overvoltage.
- It provides a smooth, fresh surface for the reaction.
- Each drop remains unaffected and does not become contaminated by the deposited metal.
- Diffusion equilibrium is readily established at mercury-solution interface.
Some of the disadvantages of dropping mercury electrode(DME) are as follows:
- It is poisonous so care should be taken in its handling.
- Surface area of a drop of mercury is never constant.
- Applied voltage produces changes in surface tension and hence change in drop size.
- Mercury has limited applications in analysis of more positive potential range.
Following care must be taken while using dropping mercury electrode:
- Pure and triple distilled mercury should be used in DME
- Tip of DME should be always immersed in water when not in use.
- Tip of DME should be cleaned by dipping in nitric acid.
- The DME assembly should be mounted vertical on a heavy stand to be free from vibrations.
- It is essential to use clean and dust free tubing while setting the DME.
- There should be sufficient mercury in reservoir so that the pressure changes are negligible.