Electrophilic Substitution 1st or 2nd Order

[rocketbooster]

I understand the mechanism and all that. What I don't get is if it's a 2nd or 1st order reaction. I don't see how it cannot be 2nd order, but the GS1 test says it's 1st order.

Okay, take the example benzene + Br2 (FeBr3)-----> bromobenzene.

This is obviously an electrophilic substitution. Is it 1st order or 2nd order? The bromine is first added by addition of the electrophile to a pi-bond of the benzene (nucleophile). Thus, the reaction begins with the reaction between the nucleophile and electrophile. How is that not 2nd order? Technically, the very 1st step is between Br2 and FeBr3 to form a complex with Br+, which acts as the electrophile to add to benzene. Even in that case, that step is still between 2 compounds, thus 2nd order. How can this be a 1st order rxn?

This question is from the GS1 BS. I got it wrong because it says it's a 1st order reaction, but the answer explanation only tells you why it's electrophilic substitution and not why it's 1st order over 2nd order.

So, I'm confused. Is this simply a mistake by GS or is this question actually 1st order? Someone please explain why if it is indeed 1st order. Thanks!

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[chemtopper]

You are right it is not first order but is a second order reaction
It has three steps in its mechanism
step 1- formation of electrophile
RCl + AlCl3 ---> AlCl4- + R +
step 2 is attack of electrophile on the ring
R+ + C6H6 ---> C6H6R+ ( slow step)
step 3 is elimination of H + from substituted ring.
C6H6R+ ----> C6H5R + H+ ( fast)
so the slow step is going to determine the order of the reaction .