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Indian Forest Service (Mains)

Chemistry optional

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

Paper I covers physical and inorganic chemistry.

Indian Forest Service (Mains), Chemistry optional · 2022 · Paper I

Q4(a). Excluded volume of hard-sphere molecules

Question

What is excluded volume? Explain with illustration. Show that the excluded volume per molecule is four times the actual volume of the gas molecule.

Answer in brief

The pair-exclusion volume is 8v₀; accounting for pair double-counting gives the van der Waals excluded-volume parameter per molecule b₀ = 4v₀.

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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 modelreal gasescovolume

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