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Chemical Kinetics

Question
CBSEENCH12006394

For the reaction A → B + C, the following data were obtained:

t in seconds

0

900

1800

Cone. of A

50.8

19.7

7.62

Prove that the reaction is of first order of A to decompose to one-half.

Solution

For the first order reaction can given by
 
k = 2.303tlog A0At

At t = 900 seconds, 

A0 = 50.8  and At = 19.7 at t = 1800 seconds, A0 = 50.8  and At = 7.62
                                                                 k = 2.303tlog A0At
(i)                         k=2.303900 slog50.819.7 = 2.303900 s× 0.4114 = 1.048 × 10-3 s-1

(ii)                        k = 2.3031800 slog50.87.62 = 2.3031800 s×0.839 = 1.052 × 10-3 s-1


Since the value of k is both case is almost same thus it is first order reaction.