Welcome Guest Search | Active Topics |

Tag as favorite
Classroom companion lecture 2
Michelle_6624
#1 Posted : Wednesday, June 16, 2021 9:35:53 PM
Rank: Newbie

Groups: Registered
Joined: 5/7/2021
Posts: 4

Thanks: 0 times
Was thanked: 0 time(s) in 0 post(s)
Hello,

I was wondering why review question 11. iii was C (talks about thin layer chromatography). (there was no explanation at the end of the book)
INSTR_Kailey_109
#2 Posted : Thursday, June 17, 2021 2:35:09 PM
Rank: Advanced Member

Groups: Registered
Joined: 6/4/2020
Posts: 31

Thanks: 0 times
Was thanked: 0 time(s) in 0 post(s)
Hi Michelle,

We'll need to wait on a specialist to give you more information on the question (I can't!) but I just wanted to flag that the answer given for ChemOChem CC Lesson 2 Review Question 11 Part III is B, not C.
INSTR_Molly_129
#3 Posted : Sunday, June 20, 2021 8:01:53 PM
Rank: Advanced Member

Groups: Registered
Joined: 5/23/2021
Posts: 64

Thanks: 0 times
Was thanked: 0 time(s) in 0 post(s)
Hey Michelle,

I absolutely LOVE this question, because it really dives into the theory that is behind TLCs. The idea is that the reason why things move far, or not so far in TLCs, is due to the H-bonding interactions that can occur between solvent/materials/plate. The plates used in TLCs generate hydrogen bonding and so, when things are present that has hydrogen bonding capabilities, it will drown out the ability of the silica plate to polar-bond to the material ran on the plate.

Let's look at the solvent now. By using methanol instead of the hexane/ether mixture, we are now providing PLENTY of hydrogen bonding in the solvent, as methanol has those -OH bonds that are great for hydrogen bonding. This drowns out the available hydrogen bonding partners from the silica plate that are available to hold on to the compound you are running up the plate to keep it lower, and so, it will help all components move further up the plate.

I hope that that's helpful. Please let me know if you have any more questions.

Cheers,

Molly
Users browsing this topic
Guest
Tag as favorite
You cannot post new topics in this forum.
You cannot reply to topics in this forum.
You cannot delete your posts in this forum.
You cannot edit your posts in this forum.
You cannot create polls in this forum.
You cannot vote in polls in this forum.

Clean Slate theme by Jaben Cargman (Tiny Gecko)
Powered by YAF | YAF © 2003-2009, Yet Another Forum.NET
This page was generated in 0.081 seconds.