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UPSC Civil Services (Mains)

Chemistry optional

  • 2 papers
  • 250 marks each
  • 3 h per paper
  • 5 of 8 questions, Q1 and Q5 compulsory

Paper I covers physical and inorganic chemistry.

UPSC Civil Services (Mains), Chemistry optional · 2021 · Paper I

Q5(a). Rate constant and half-life of a zero-order reaction

Question

Derive an equation for rate constant of a zero-order reaction. Show that half-life period of the reaction is proportional to the initial concentration of reactant.

Answer in brief

k = ([A]₀ − [A])/t (unit mol L⁻¹ s⁻¹) and t₁/₂ = [A]₀/2k, so t₁/₂ ∝ [A]₀.

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

Coverszero-order reactionhalf-lifeintegrated rate lawrate constant units

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