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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 · 2022 · Mains Paper III

Q4(c). Thermogram of calcium oxalate monohydrate

Question

Using a thermogram, describe the thermal decomposition events of calcium oxalate monohydrate in the temperature range between 25 °C and 1000 °C.

Answer in brief

Three separate mass-loss steps: H₂O (12.3 %), then CO (19.2 %), then CO₂ (30.1 %); plateaus of CaC₂O₄, CaCO₃ and CaO (final residue 38.4 %).

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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: thermogravimetry, DTA and the calcium oxalate thermogram, with every Civil Services, IFoS and Geo-Scientist PYQ →

Coversthermogramcalcium oxalate monohydratethermogravimetryCaC₂O₄·H₂O decompositionTG DTG

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