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UPSC Combined Geo-Scientist

Chemist

  • 3 descriptive papers
  • 200 marks each
  • 3 h per paper

Mains Paper I covers inorganic chemistry.

UPSC Combined Geo-Scientist, Mains · 2023 · Mains Paper I

Q8(a)(i). Cyanide determination with silver nitrate

Question

Outline the underlying principle for the determination of cyanide with Ag⁺ titrimetrically providing necessary equations. How can the end point be detected?

Answer in brief

Ag⁺ binds two CN⁻ to form soluble [Ag(CN)₂]⁻. The first persistent turbidity from excess silver marks the Liebig end point.

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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: EDTA titrations, metal-ion indicators and masking, with every Civil Services, IFoS and Geo-Scientist PYQ →

CoversLiebig methodcyanide determinationAgNO3 titration[Ag(CN)2]-Deniges modification

All parts of Question 8