Question

A certain reaction proceeds in a sequence of three elementary steps with rate constants k1, k2 and k3. If the observed rate constant, Kobs, of the reaction is expressed as Kobs = K3 [K1/K2]1/2, then what is the observed energy of activation of the reaction?

• A. (A) E3+12(E1E2)
• B. (B) E3+(E1−E22)
• C. (C) E3(E1E2)1/2
• D. (D) E3+E1+E22

Answer 1

Answer: (B)

(B) E3+(E1−E22)

Answer 2

Explanation:
Kobs=K3[K1K2]1/2=A3⋅e−E3/RT×[A1e−E1/RTA2e−E3/RT]1/2Kobs=A3A1A2×e−[E2RT+12(E1−E2FT)]⇒Kobs=A⋅e−Eobs/Fr∴Eobs=E3+(E1−E22)