Q113 · CSIR NET Chemistry, December 2012
Paper: CSIR NET December 2012 · Subject: Physical Chemistry · Chapter: Chemical Kinetics · Topic: Chemical Kinetics – General · Marks: 2 · Difficulty: Hard
In the Lindemann mechanism of unimolecular reactions, the observed order at low concentration is:
(a)0.5
(b)1
(c)1.5
(d)2
Answer
Answer: D ✓ checked by 4AB · confidence high
The source book printed no answer; this one was worked out and checked — see the explanation.
Explanation
Lindemann: rate = k₁k₂[A]²/(k₋₁[A] + k₂). At low concentration k₋₁[A] ≪ k₂, so rate ≈ k₁[A]² — second order (first order only at high pressure).
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