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UPSC Combined Geo-Scientist

Chemist

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

Mains Paper III covers analytical and organic chemistry.

UPSC Combined Geo-Scientist, Mains · 2021 · Mains Paper III

Q2(a). Rf value in thin layer chromatography

Question

What do you mean by Rf (retardation factor) as used in Thin Layer Chromatography (TLC)? What is the unit of Rf? On which factor(s) does this Rf value depend(s)? What is the utility of this factor?

Answer in brief

Rf = distance moved by the solute ÷ distance moved by the solvent front; no unit, value 0 to 1; characteristic of a compound under fixed conditions, so it serves to identify it.

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Topic notes: chromatography and solvent extraction (plates, resolution, van Deemter, HPLC, GLC, ion exchange, Craig), with every Civil Services, IFoS and Geo-Scientist PYQ →

CoversRf valuethin layer chromatographyTLCretardation factor

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