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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(b). Rotational partition function

Question

Deduce the expression for the rotational partition function of a rigid heteronuclear diatomic rotator.

Answer in brief

The exact sum is qrot = Σ(2J + 1)e^(−θr J(J+1)/T); for T ≫ θr, qrot ≈ 8π²IkBT/h² = T/θr.

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Topic notes: statistical thermodynamics, the Boltzmann distribution, partition functions and the Sackur–Tetrode equation, with every Civil Services, IFoS and Geo-Scientist PYQ →

Coversrotational partition functionrigid rotorheteronuclear diatomicsymmetry numberrotational temperaturestatistical thermodynamics

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