1.

The rate constant for the first order decomposition of H_(2)O_(2) is given by the following equation : logk=14.2 - (1.0xx10^(4))/(T) Calculate E_(a) for this reaction and rate constant k if its half-life period be 200 minutes. [Given : R=8.314 JK^(-1)"mol"^(-1)]

Answer»

Solution :A general equation relating log k and `E_(a)` is GIVEN by
`log k =log A-(E_(a))/(2.303RT) ""…(i)`
The given equation is
`log k=14.2 -(1.0xx10^(4))/(T)""…(ii)`
On comparing equations (i) and (ii), we have
`(E_(a))/(2.303RT)=(1.0xx10^(4))/(T)`
or `E_(a)=1.0xx10^(4)xx2.303 xx R "" ...(III)`
Substituting the value of R in equation (iii), we have
`E_(a)=1.0xx10^(4)xx2.303xx8.314=191471.4"J mol"^(-1)`
Half-life PERIOD for a first order reaction
`t_(1//2)=(0.693)/(k)`
or `ko=(0.693)/(t_(1//2))=(0.693)/(200"min")=0.0034" min"^(-1)`


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