Question

Given the following proposed mechanism:

A3 ⇌ A2 + A K1, fast step

A + A3 → 2A2 k2, slow step

The rate rate law is Question 5 options:

a.)second order in A3 and first order in A2

b.)second order in A3 and zero order in A2

c.)first order in A3 and zero order in A2

d.)inverse order, i.e., -1, in A3 and second order in A2

e.)second order in A3 and inverse order, i.e., -1, in A2

f.)zero order in A3 and second order in A2

g.)first order in A3 and first order in A2

Answer 1

A_3 Equilibrium A_2 + A k_1 fast step A + A_3 rightarrow 2A_2 k_2 slow step From slow determining rate step r = -d[A_3]/dt = k_1[0][0_3] From the fast equilibrium step k = [A_2][A]/[A]_3 or [A] = K[A_3]/[A_2] substituting for [A] in the expression for r, we have r = K_1K[A_3]^2/[A_2] = K[A_3]^2/[A_2] where k =k_1K Thus given mechanism is consistent with the rate law. Therefore answer is e) second order is A_3 and inverse order ie -1 in A_2