The rate of a first-order reaction is 0.04 m o l l - 1 s - 1 at 10 second and 0.03 m o l l - 1 s - 1 at 20…

The rate of a first-order reaction is 0.04 mol l-1s-1 at 10 second and 0.03 mol l-1s-1 at 20 seconds after initiation of the reaction. The half-life period of the reaction is:
  1. 24.1 s
  2. 34.1 s
  3. 44.1 s
  4. 54.1 s

Solution

RateTime0.04100.0320
For first order reaction r ∝ conc.
r1r2=C1C2=43
∴k=2.303t2-t1log⁡C1C2
⇒0.693t1/2=2.30320-10log⁡43
On solving t1/2=24.1 s

Asked in: NEET 2016 (Phase 1)

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