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Pre- equilibrium approach

Posted: Sun Mar 19, 2017 6:54 pm
by Kira_Maszewski_1B
When are we supposed to use the pre equilibrium approach? If there is an intermediate in the first step and the first step is also the slow step, would we need to use the pre-equilibrium approach to find the rate law and get rid of the intermediate?

Re: Pre- equilibrium approach

Posted: Sun Mar 19, 2017 7:02 pm
by Theresa Dinh 3F
Usually when there's an intermediate involved, you have to use the pre equilibrium approach.

Re: Pre- equilibrium approach

Posted: Sun Mar 19, 2017 10:17 pm
by divya_devineni_2E
You do not include the intermediate if it is not in the slowest step

Re: Pre- equilibrium approach  [ENDORSED]

Posted: Mon Mar 20, 2017 12:59 am
by Vincent Tse 2B
You apply the pre-equilibrium approach when the mechanism has its first step as fast; this will create a "bottleneck" effect which results in a build-up of intermediates. You can then assume the first step reaction to be at an equilibrium, and use it to help you get rid of the intermediate concentrations in your slow-step rate law.