Molecularity

[TiffanyL1G]

I think the slowest elementary step determines the molecularity of the reaction, but if a molecule in the previous fast equation were to cancel with a molecule in the slow equation. Would that molecule still be used to determine molecularity?

For example:


Do the 2B's cancel with each other and so the molecularity would be unimolecular or do we have to consider B along with C (which makes the reaction, bimolecular)?

[Emmaraf 1K]

It doesn't really make sense to talk about the molecularity of the overall reaction. It only makes sense to talk about the molecularity of the elementary steps. Molecularity refers to how many and which molecules must collide with each other for the reaction to be carried out at each step.