Slow Steps

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nathansalce 3e
Posts: 52
Joined: Thu Jul 27, 2017 3:01 am

Slow Steps

Postby nathansalce 3e » Thu Mar 15, 2018 3:12 am

In the example Professor was showing today, are you essentially solving for the slow step? You dont determine from the beginning which one is which step, you just see the potential to substitute an intermediate to create the slow step out of one of the steps? Is it something like that? Because the slow step is the one that matches the observed rate law...

Wenxin Fan 1J
Posts: 53
Joined: Thu Jul 13, 2017 3:00 am

Re: Slow Steps

Postby Wenxin Fan 1J » Thu Mar 15, 2018 9:51 am

Yes, you need to identify the slow step to see if it fits the experimentally observed rate law. However, you may not always be told which step is the slow step so you should try to see which step would work as the slow step if you apply what you know about the characteristics of a slow step and if you can incorporate other steps to substitute reactants/products in the slow step to get the rate law.

Erica Nagase 1H
Posts: 30
Joined: Sat Jul 22, 2017 3:00 am

Re: Slow Steps

Postby Erica Nagase 1H » Thu Mar 15, 2018 10:14 am

The example from lecture was trying to identify which proposed mechanism agrees with the given rate law. If the second step is slow and its rate law contains an intermediate, then we use the equilibrium constant K expression to substitute for the intermediate (we assume the reaction before the rate-limiting step is at equilibrium).

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