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UPSC Civil Services (Mains)

Chemistry optional

  • 2 papers
  • 250 marks each
  • 3 h per paper
  • 5 of 8 questions, Q1 and Q5 compulsory

Paper I covers physical and inorganic chemistry.

UPSC Civil Services (Mains), Chemistry optional · 2024 · Paper I

Q4(b)(i). Polarography and concentration polarisation

Question

What is polarography? Explain the concentration polarization at the electrode. Give the labelled diagram of the polarographic cell assembly.

Answer in brief

Polarography is an electroanalytical method in which the current through a dropping mercury electrode is recorded while the applied potential is slowly changed; the polarogram identifies an ion by its half-wave potential and gives its concentration from the diffusion current.

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The full model answer

As written for the answer booklet: the diagram carries the working, the lines stay short. Read here only; it is not offered as a download.

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Topic notes: electrode kinetics: the double layer, overpotential, the Butler–Volmer and Tafel equations, polarography and voltammetry, with every Civil Services, IFoS and Geo-Scientist PYQ →

Coverspolarographydropping mercury electrodeconcentration polarisationIlkovič equationhalf-wave potentialdiffusion current

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