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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 · 2017 · Mains Paper II

Q5. Electrolyte dissociation from freezing points

Question

Two aqueous 1:1 electrolyte solutions A and B, of stated concentration 0.1 (interpreted as mol kg⁻¹), freeze at -0.360° C and -0.208° C. Calculate their van' t Hoff factors, ionisation degrees and likely electrolyte nature. Kf=1.86 K kg mol⁻¹.

Answer in brief

iA=1.935, iB=1.118; ideal particle-count estimates are α_A=93.5% and α_B=11.8%.

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CoversElectrolyte dissociation from freezing pointsColligative properties