Question

The manganese(II)-catalyzed redox reaction between cerium(IV) and thallium(I) is thought to proceed by a three-step mechanism:

Ce4+(aq) + Mn2+(aq) --> Ce3+(aq) + Mn3+(aq) (slow)
Ce4+(aq) + Mn3+(aq) --> Ce3+(aq) + Mn4+(aq)
Mn4+(aq) + Tl+(aq) --> Mn2+(aq) + Tl3+(aq)

a. If the first step of this mechanism is rate-determining (slow), choose the correct rate law for the overall process.


1. Rate = k [Ce4+]2
2. Rate = k [Ce4+] [Tl+]
3. Rate = k [Mn2+] [Mn3+]
4. Rate = k [Mn2+] [Ce4+]
5. Rate = k [Mn3+] [Tl+]
6. Rate = k [Ce4+]2 [Tl+]

b. Choose the correct chemical equation for the overall process.

1. Ce4+(aq) + Mn2+(aq) --> Ce3+(aq) + Mn3+(aq)
2. Ce4+(aq) + Mn3+(aq) --> Ce3+(aq) + Mn4+(aq)
3. 2Ce4+(aq) + Tl+(aq) --> 2 Ce3+(aq) + Tl3+(aq)

Answer 1

a) Rate = k [Mn2+] [Ce4+]

b) 2Ce4+(aq) + Tl+(aq) --> 2 Ce3+(aq) + Tl3+(aq)

Step-by-step explanation:

A non elementary reaction is a reaction that does not occur in a single reactive encounter.

Again, the rate determining step in a reaction sequence is the slowest step in the sequence. Usually, the rate law is derived from the concentration of species involved in the rate determining step as shown in the answer above.

Secondly, the overall equation is obtained by summing up all the reactants and products and cancelling out intermediate species. This leaves us with the overall balanced reaction equation as shown in the answer.