For the following reactions:
it was found that Ea is decreased by 30 kJ/mol in the presence of a catalyst. If the rate remains unchanged, the activation energy (in KJ/mol) for the catalyzed reaction is ( Assume the pre-exponential factor is the same):
The number of molecules with energy greater than the threshold energy for a reaction increases five fold by a rise of temperature from 27°C to 42°C. Its energy of activation in J/mol is _______. (Take ln 5 =1.6094 ; R=8.314 J mol-1 K-1)
A flask contains a mixture of compounds A and B. Both compounds decompose by first-order kinetics. The half-lives for A and B are and
, respectively. If the concentrations of A and B are equal initially, the time required for the concentration of A to be four times that of B (in s) is : (Use e ln 2 = 0.693)