Elementary rate laws and intermediates

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LChiu 2K
Posts: 1
Joined: Wed Nov 19, 2014 3:00 am

Elementary rate laws and intermediates

When writing an elementary rate law for a reaction mechanism with multiple steps, are intermediates included?

Niharika Reddy 1D
Posts: 127
Joined: Fri Sep 26, 2014 2:02 pm

Re: Elementary rate laws and intermediates

I'm not sure if you mean the rate law for a particular elementary step by "elementary rate law", but intermediates should not be included in the final rate law for the overall reaction after taking all the different elementary steps of the reaction mechanism into account. If an intermediate is included in the slow step's rate law, then use the pre-equilibrium approach to substitute out the intermediate.

If you are looking for the rate law for a particular elementary step on its own, I would assume it is fine to use intermediates since the intermediates of the overall reaction mechanism don't act as intermediates when looking at a particular step and not the overall reaction.