Chemical Kinetics

Chemical Kinetics

Question

The rate constant for the first-order decomposition of H2O2 is given by the following equation:
log space k space equals space 14.2 space minus space fraction numerator 1.0 space x space 10 to the power of 4 over denominator T end fraction K
Calculate Ea for this reaction and rate constant k if its half-life period be 200 minutes. (Given: R = 8.314 JK–1mol–1).

Answer

Given:
Order of the reaction = First order
t1/2 = 200 minutes = 200 × 60 = 12,000 seconds The relation between t1/2
and k is given by t1/2 = 0.693/k
k = 0.693/12000 = 5.7 × 10−5
The rate constant for the first-order decomposition of H2O2 is given by
log space k equals space 14.2 space minus fraction numerator 1.0 space x space 10 to the power of 4 over denominator T end fraction space.... left parenthesis i right parenthesis space

B y space A r r h e n i u s space e q u a t i o n

l o g space k equals space l o g space A space minus space fraction numerator E subscript a over denominator 2.303 R T end fraction space.... left parenthesis i i right parenthesis

C o m p a r i n g space left parenthesis i right parenthesis space a n d space left parenthesis i i right parenthesis comma space w e space g e t

E subscript a space equals 1.91 space x space 10 to the power of 5

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