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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 · 2022 · Mains Paper II

Q13(a). Parallel (side) reactions: rate equation and k₁, k₂

Question

Derive the rate equation for the overall reaction of type A → L (rate constant k₁) and A → M (rate constant k₂) [parallel reaction scheme given in the paper]. How can we evaluate individual rate constants k₁ and k₂?

Answer in brief

−d[A]/dt = (k₁ + k₂)[A], [A] = [A]₀ exp[−(k₁ + k₂)t]; the first-order plot gives k₁ + k₂ and the product ratio gives [L]/[M] = k₁/k₂.

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Coversparallel reactionsside reactionsfirst-order kineticsrate constantsproduct ratio

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