A first order reaction is 50% completed in 40 minutes at 300 K and in 20 minutes at 320 K. Calculate the activation energy of the reaction.

(Given: log 2 = 0.3010, log 4 = 0.6021, R = 8.314 JK–1 mol–1)

Rate constant for first order reaction is given by:



Where k is the rate constant, t is the time, Ro is the initial concentration and R is the final condition.


At 300K,


=0.058 × log 2


=0.058 × 0.301


=0.017


At 320K,


=0.11× log 2


=0.11 × 0.3010=0.034


Now,


log = ()


Where Ea is the activation energy


K1, T1 is the temperature of 300 K


K2, T2 is the temperature of 320 K


Putting the value in the above equation,


K



Ea=28,805.7 j mol-1


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