Organic Chemistry / Rate Calculations
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Solution: Classify the elementary steps in the mechanism according to ...


Classify the elementary steps in the mechanism according to their molecularity.

A. Step 1 is unimolecular; step 2 is bimolecular.

B. Step 1 is bimolecular; step 2 is unimolecular.

C. Both steps are unimolecular.

D. Both steps are bimolecular. 

Video Transcript

Alright guys, so now let's take a look at this question, it says, it wants us to classify the elementary steps on the mechanism according to their molecularity. Now, you can see our answers here, we're choosing between unique molecular and biomolecular, so it would probably be good to have some examples of each, right? So, which one do you think it is right off the bat? we're looking at these and then again if we scroll up we're going to have our reaction and just so you guys know we're talking about these two steps right here, step one and step two. Alright. So, be thinking of these reactions and now let's talk about unimolecular and bimolecular. Alright, so let's scroll down. Now, let's start off with unimolecular, what do you think unimolecular is? if you could show an example of it, we're going to start with say a some kind of compound and if it's unimolecular that means we're going to just go to our products, okay? With that a, whatever our products may be, now bimolecular on the other hand is just a slight bit different, so what do you think bimolecular is knowing what you see in unimolecular? Well, we're going to start out with say a again and you think we're going to go straight to our products, products like that or what do you think we're going to do? when bimolecular we can have say A plus B and go to our products but can you think of one more example of that, you can also have A plus A and go to our products, okay? So, those are just some general examples, so let's see if we're starting out with just an A, right? one reagent, or we're starting out with 2, remember that our answer has to do with either they're both uni, they're both bimolecular or one is unimolecular, the other one is bi or vice versa, okay? So let's break it down, let's start with our first one, step one, do you think it's from A to products or A plus B to products? Well, let's say this is our A, right? this would be our products, right? That's A and this is our product, so this resembles what? unimolecular, right? We're going to say unimolecular, and what about step two? I want you guys to try this one on your own and then when you come up with, they can either be uni again or bimolecular, which one you think it is? well, label your A or your A and B or A and A, we know that these are going to be our products, we have that double bond and notice that we can label this A and B because they're different. So, since we start with an A and B and we go to our products, what do you think step two is then uni or bimolecular? Yep, that's right it was bimolecular and the first one would be unimolecular, so let's see where we see that in our answer choices, we know it's not going to be D or C and we saw that the first step was actually uni and the second step was bimolecular. Alright guys, so we can eliminate B as, B as well, right? Cross that out, we know that our answer here must be A. Alright guys, so I hope that made sense and let me know if you have any questions.