UPSC Combined Geo-Scientist, Mains · 2023 · Mains Paper II
Q13(b). Time at which [B] is a maximum
Question
For the above reaction, if the rate constant k₁ is 5.0 × 10⁶ s⁻¹ and k₂ is 3.0 × 10⁶ s⁻¹, determine the time at which [B] is at a maximum.
Answer in brief
tmax = ln(k₁/k₂)/(k₁ − k₂) = 2.55 × 10⁻⁷ s = 0.255 µs; there [B]max = 0.465[A]₀.
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Coversconsecutive reactionstmaxmaximum concentration of intermediatefirst-order kinetics
All parts of Question 13
- 13(a) Consecutive first-order reactions: [A], [B] and [C] against time15 marks
- 13(b) Time at which [B] is a maximum5 marks