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UPSC Combined Geo-Scientist

Chemist

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

Mains Paper II covers physical chemistry.

UPSC Combined Geo-Scientist, Mains · 2022 · Mains Paper II

Q2(b). Excluded volume is four times the molecular volume

Question

Show that the excluded volume is four times the actual volume of the gas molecule.

Answer in brief

Excluded volume per molecule = ½ × (4/3)π(2r)³ = 4 × (4/3)πr³; per mole, b = 4NA × (4/3)πr³.

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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: real gases, the van der Waals equation, critical constants and Boyle temperature, with every Civil Services, IFoS and Geo-Scientist PYQ →

Coversexcluded volumevan der Waals constant bhard-sphere modelmolecular volumereal gases

All parts of Question 2