Consider a complex reaction taking place in three steps with rate constants k_1 ,k_2 and k_3 respectively. The overall rate constant k is given by the expression k= k_1k_3k_2. If the activation energ…

Question

Consider a complex reaction taking place in three steps with rate constants

k_{1}, k_{2}

and

k_{3}

respectively. The overall rate constant

k

is given by the expression

k = \frac{k _{1} k _{3}}{k _{2}}

. If the activation energies of the three steps are 60,30 and

10 kJ mol^{- 1}

respectively, then the overall energy of activation in

kJmol^{- 1}

is…... (Nearest integer)

Accepted Answer

Correct answer: 20. (20) k_1 ,k_2 and k_3 are given as rate constants of three steps of a complex reaction. Rate constant (k) of the overall reaction is given as k= k_1k_3k_2Activation energies of the three steps are given as E_a_1=60 kJ mol^-1 ,E_a_2=30 kJ mol^-1, E_a_3=10 kJ mol^-1From Arrhenius equation, we know that k= Ae^- Ea/ RTT If E_a is the activation energy of the overall reaction, then E_a= 12(E_a_1+E_a_3-E_a_2) = 12 [60+10-30 ]=20 kJ mol^-1

Solution

More Chemical Kinetics PYQs