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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 · 2025 · Mains Paper II

Q4. Chemical potential in terms of H and U

Question

Show that μi = (∂H/∂ni)S,P,nj(j≠i) = (∂U/∂ni)S,V,nj(j≠i).

Answer in brief

μi = (∂G/∂ni)T,P,nj = (∂H/∂ni)S,P,nj = (∂U/∂ni)S,V,nj: one μi, differing only in the natural variables held constant.

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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 →

Coverschemical potentialpartial molar quantitiesGibbs fundamental equationsLegendre transformationopen system