Consider the reaction in which HCl adds across the double bond of ethene: HCl + H₂C=CH₂ → H₃C-CH₂Cl The following mechanism, with the accompanying energy diagram, has been suggested for this reaction:

Step 1 HCl + H₂C=CH₂ → H₃C=CH₂⁺ + Cl^-

Step 2 H₃C=CH₂⁺ + Cl^- → H₃C-CH₂Cl

a. Based on the energy diagram, determine which step is rate limiting.

Video transcript

Hey everyone, welcome back. We're given the energy diagram for nitrogen dioxide with carbon monoxide. And we're told that the overall reaction is here below. So we're given the proposed mechanism with two steps. We have step one here and step two here and we need to determine which step is the rate limiting step. So we should recall that our rate limiting step is another way of saying our slow step or our rate determining stuff. And so what we should recall is that our slow step means that our activation energy should be larger compared to the second step, which would be a much faster step. So looking at the first peak, we would recognize this first peak as step one, Whereas the second peak would represent step two. And so we can see that the activation energy for step one is much larger than the activation energy for step two, which has a smaller activation energy. And so what that means is that it takes step one longer too. Take place then step two. And so based on our graph, we can say therefore Step one is our rate limiting step because its activation energy for step one Is greater than the activation energy for step two. And so our final answer is going to be that Step one is our rate limiting step. So what's highlighted in yellow here is our final answer. If you have any questions, please leave them down below. Otherwise, I will see everyone in the next practice video