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verifying reaction mechanism of ozone decomposition using pre-equilibrium method

Posted: Sat Feb 18, 2017 2:47 am
by Yiling Liu 1N
example 15.7

The textbook uses the steady-state method to verify the proposed mechanism with the experimental rate law for the decomposition of ozone.
2 O3 (g) --> 3 O2 (g)

experimentally determined rate of decomposition of O3 = k[O3]^2/[O2]

mechanism proposed:
step 1 (fast) O3 <--> O2 + O
step 2 (slow) O + O3 <--> O2 + O2

I tried using the pre-equilibrium method but was unable to find an expression to substitute for the concentration of the intermediate [O] in step 2.

Is it possible to use the pre-equilibrium method in this case?

Re: verifying reaction mechanism of ozone decomposition using pre-equilibrium method  [ENDORSED]

Posted: Sat Feb 18, 2017 2:54 am
by Yiling Liu 1N
Actually never mind!

There is a pretty good online explanation for how to express [O] in terms of the things actually present in the overall reaction equation.

https://chem.libretexts.org/Core/Physic ... chanisms_1

From step 1 we can find K = [O2][O]/[O3] and then from there we know that [O]= k1/k'1 [O3]/[O2] and then can substitute back into the step 2 equation.

Re: verifying reaction mechanism of ozone decomposition using pre-equilibrium method

Posted: Sat Feb 18, 2017 1:54 pm
by Stephanie_Martinez3E
Thanks for the link! very helpful!