Question

Examine the reaction mechanism found below:
A + B​2​ → AB​2 (slow)
AB​2​ + C → AB​2​C (fast)
AB​2​C + C → B​2​C​2​ + A (fast)
B​2​C​2​ → D + E (fast)

a) Write all the reaction intermediates
b) Write all the species that can be considered a catalyst.
c) provide the overall equation for this process.
d) provide the rate law based on this mechanism.

(Note: this is thermochemistry)

I tried out a and b (I don't know if they're right, please tell me if they are) and I'm also confused for c and d.

My answers:
a) reaction intermediates : AB​2​, AB​2​C, and B​2​C​2
b) catalyst : A

Answer 1

I agree with your answers for a) and b).
for c) I did this in my head so check me out thoroughly. What you want to do is to add the equations, cancel those materials on both sides. What you're left with is the final overal aequation.
I came up with this:
B2 + 2C ==> D + E
d) The rate law is based on the slow step.
rate = k(B2)

Answer 2

I have a question about the rate law, I understand that it is based on the slow step, but I don't understand why is it rate = k [B2] instead of rate = k [A] [B2]? Also my teacher said that I needed to show my steps but I don't know how to since this mechanism is based on variable, how do I show my steps?