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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 · 2024 · Mains Paper II

Q13(b). Activity as the thermodynamic counterpart of pressure

Question

Show that the activity is the thermodynamic counterpart of gas pressure.

Answer in brief

For an ideal gas μ = μ° + RT ln(p/p°); for any substance in any phase μi = μ°i + RT ln ai: the activity ai takes exactly the place of p/p°.

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The full model answer

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: chemical potential, partial molar quantities, the Gibbs–Duhem equation, fugacity and activity, with every Civil Services, IFoS and Geo-Scientist PYQ →

Coversactivityfugacitychemical potentialstandard statefugacity coefficient

All parts of Question 13