Consider the following energy diagram for the reaction A D: Based on the following elementary steps, what is the predicted rate law for this reaction? (a)rate-k (b) rate k B] (c) rate -k[C] (d) rate k[A][B] (e) rate-k[A] Rxn Solution the highest peak represents the slowest step in this case , the 2nd peak is the highest so the 2nd step is the slowest B ---> C the rate depends on the slowest step so rate = k1 [B] now from the equilibrium reaction A <---> B Keq = [B]/[A] [B] = Keq [A] now rate = k1 x Keq [A] rate = (k1 x Keq) [A] rate = k [A] so the answer is e) rate = k [A] .

1. Consider the following energy diagram for the reaction A D: Based on the following elementary
steps, what is the predicted rate law for this reaction? (a)rate-k (b) rate k B] (c) rate -k[C] (d) rate
k[A][B] (e) rate-k[A] Rxn
Solution
the highest peak represents the slowest step
in this case , the 2nd peak is the highest
so the 2nd step is the slowest
B ---> C
the rate depends on the slowest step
so
rate = k1 [B]
now
from the equilibrium reaction A <---> B
Keq = [B]/[A]
[B] = Keq [A]
now
rate = k1 x Keq [A]
rate = (k1 x Keq) [A]
rate = k [A]

2. so
the answer is e) rate = k [A]