Intermediate and rate law [ENDORSED]

[Nancy Le - 1F]

Why can't an intermediate be included in the rate law?

[Farah Ahmad 2A]

Intermediates aren't included in the rate law because within the whole mechanism they are produced and used up, so there is no net effect on the rate from the intermediate, so there is no reason to include something that doesn't affect the rate in the rate law.

[Nancy Le - 1F]

I see, that makes sense! Does it have anything to do with the reactivity of the intermediate as well?

[Christine Wastila 1H]

If a compound or element is both produced and used up, it is an intermediate regardless of how reactive it may be. Most intermediates are very reactive, which is why they are typically short-lived molecules that quickly convert to a more stable form. In other words, they are used up fast.