By Sunil Bhardwaj


In 1922, Heyrovsky, discovered a technique with the help of which, qualitative, quantitative and even mixture can be analyzed qualitatively and quantitatively, the technique is known as Polarography. In this case electrolysis of experimental solution is done. The cathode is polarized electrode (where deposition takes place) and anode is non polarized electrode.

In Polarography we plot a graph of current in \(\mu A\) V/s potential applied in volts. The graph obtained is known as Polarogram. It is S shaped wave. The Polarogram is divided into three portions.


Residual current \((i_R)\): The current which is associated with the impurities is known as Residual current. AB portion of the graph corresponds to residual current \(i_R\)

Diffusion current \((i_d)\): At the point B, the potential applied is equal to reduction potential of metal ions. The metal gets reduced over DME and current is produced.$$ { M }^{ n+ }+{ ne }^{ - }\longrightarrow { M } $$ $$ { M }+{ Hg }\longrightarrow { M(Hg) } $$ As large amount of metal ions are reduced, so the current will increase rapidly. At the point C reduction is complete.$$ i_d = i_L - i_R $$

Limiting Current \((i_L)\): At the point C, all the metallic ions are reduced. As no more metallic ions, so no further increase of current and now the current remain constant. This constant current is known as Limiting current.

Half wave potential \(({ E }_{ 1/2 })\): The halfwave potential is defined as that potential at which half of the total metal ions present in the electrolyte are reduced. OR when \(i= id/2\) then, \(E = { E }_{ 1/2 }\)

MCQ on Polarography from Analytical Chemistry
Prof. Gianfranco Coletti

Shared publicly - 2019-08-23 00:00:00

Don’t want your columns to simply stack in some grid tiers? Use a combination of different classes for each tier as needed. See the example below for a better idea of how it all works.

Prof. Maheshwar Sharon

Shared publicly - 2019-08-24 00:00:00

For grids that are the same from the smallest of devices to the largest, use the .col and .col-* classes. Specify a numbered class when you need a particularly sized column; otherwise, feel free to stick to


Shared publicly - 2023-02-28 11:09:52

this is


Shared publicly - 2023-02-28 10:48:10


Latest News

  • Become an Instructor 4 March, 2018

    Apply to join the passionate instructors who share their expertise and knowledge with the world. You'll collaborate with some of the industry's best producers, directors, and editors so that your content is presented in the best possible light..

More Chapters

  • Chromatography
  • Solvent Extraction
  • Gravimetric Analysis
  • Optical Methods
  • Polarography
  • Other Subjects

  • English
  • Applied Physics
  • Environmental Studies
  • Physical Chemistry
  • Analytical Chemistry
  • Organic Chemistry
  • Soft Skills
  • Engineering Drawing
  • General Medicine
  • Mathematics
  • Patente B Italia
  • Adult Education
  • Engineering Chemistry
  • Conceptual Physics
  • Aptitude