Free radical halogenation question

[Attraction]

Homework Statement

The initiation step in chlorination of methane is as follows...

http://upload.wikimedia.org/wikipedia/en/thumb/3/32/MethaneChlorinationMechanismInitiation.svg/260px-MethaneChlorinationMechanismInitiation.svg.png

We get two chlorine radicals as a result.

Next we have two propagation steps

http://upload.wikimedia.org/wikipedia/en/4/48/MethaneChlorinationPropagationStep.svg (won't let me embed the pic, sorry guys!)Ok, my understanding of this is... in the initiation step, the Cl₂ was broken into two Cl radicals. ONE Cl radical moved on to the next step and reacted with the methyl group forming a methyl radical and HCl. THEN, the methyl radical reacted with Cl₂ to form chloromethane and a chlorine radical.

My question is, Where does the SECOND Cl radical that was produced in the initiation step go? Because only ONE Cl radical reacted with the methyl group and then the methyl radical reacted with Cl₂. In my mind, there is a Cl radical unaccounted for, but this is not explained in any example I can find (in a book or online)?

Thanks!

 

[Ygggdrasil]

It performs the same reaction with other molecules of methane. Eventually, you can get termination reactions that get rid of the radicals (often, this involves two radicals bonding together, e.g. Cl• + Cl• --> Cl₂).

 

[Blueshift5]

I can understand your confusion about the second chlorine radical in the initiation step of chlorination of methane. However, it is important to note that the second chlorine radical is not unaccounted for. In fact, it is involved in the second propagation step, as shown in the second diagram you provided.

In the first propagation step, one chlorine radical reacts with the methyl group to form a methyl radical and HCl. This methyl radical then reacts with another chlorine molecule to form chloromethane and a second chlorine radical. This second chlorine radical then goes on to react with another methyl group, continuing the propagation process.

Therefore, both chlorine radicals produced in the initiation step are used in the propagation steps, and none are left unaccounted for. This is a crucial aspect of the free radical halogenation process, as it ensures that the reaction continues and multiple chlorination products are formed.

I hope this explanation helps to clarify your understanding of the process. If you have any further questions, please feel free to ask. it is important to always question and seek a deeper understanding of scientific concepts. Keep up the curiosity!