1 / 10

Polarography

Polarography. Polarography is a subclass of voltammetry where the working electrode is a dropping mercury electrode (DME). It is current versus potential are recorded when gradual changing current is take place when current applied to cell. A cell containing :

wes
Télécharger la présentation

Polarography

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Polarography

  2. Polarography is a subclass of voltammetry where the working electrode is a dropping mercury electrode (DME). It is current versus potential are recorded when gradual changing current is take place when current applied to cell.

  3. A cell containing : • Solution of interest (electroactive substance) • Stable reference electrode. e.g : calomel electrode. • Small area of indicator electrode (DME) • Auxiliary or counter electrode .

  4. Mercury pool

  5. Hg will dropped in stable flow rate 5- 30 drops/min. • Volts applied 50 – 200 mv/min • Drop life 2 – 12 sec. • Potential range (+ 0.4) – (-2) V

  6. Advantage of Hg electrode • As the Hg capillary very narrow so, able to analyse very small volume of analyte. • Surface of electrode is very reproducible . • Surface area of electrode can be calculated from the weight of drops.

  7. Disadvantage • Limited potential (+0.4) – (-2) V. • Capillary is very small so easily to bloked .

  8. Qualitative polarogram Polarographic spectrum

  9. Limiting current Quantitative polarogram Diffusion current residual current

  10. Factors affecting diffusion current (Ilkovic equation) ίd = 708 n C D½ m ⅔ t⅙ • n : change in valency • C : concentration • D : diffusion coefficient. • m: flow rate of mercury dropping. • t : life time of mercury drop.

More Related