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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 · 2024 · Mains Paper III

Q4(a). Plate height; number of plates from a chromatographic peak

Question

What is plate height (H)? Calculate the number of plates in the column resulting in chromatographic peak with tR = 52.3 sec and W₁/₂ = 5.3 mm. Also comment on the efficiency of the column. [Given: N = 5.545 (tR/W₁/₂)²]

Answer in brief

H is the length of column that holds one theoretical plate, H = L/N. Here N = 5.545 (52.3/5.3)² ≈ 540 plates, a low number, so the column is not efficient.

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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 →

Coversplate heightHETPtheoretical platescolumn efficiencyvan Deemter equationchromatography

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