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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 · 2023 · Paper I

Q5(a). Integration of a reversible first-order reaction

Question

Starting with pure A (of concentration a) in the reversible reaction A ⇌ B (forward rate constant k₁, backward k₂), derive t = [k₂(K + 1)]⁻¹ ln{Ka/[Ka − (K + 1)x]}, where K is equilibrium constant and other symbols have their usual meanings.

Answer in brief

The required expression is t = {k₂(K + 1)}⁻¹ ln[Ka/{Ka − (K + 1)x}], with K = k₁/k₂; the printed kₐ must be read as Ka.

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Topic notes: rate laws, integrated rate equations and half-lives, with every Civil Services, IFoS and Geo-Scientist PYQ →

Coversreversible first-order reactionopposing reactionsintegrated rate lawequilibrium constantchemical kinetics

All parts of Question 5