Organic Chemistry...

Been a while since I've done this, but if you draw a Newman projection of iodoethane with the CH3 to the back, then a iodine would be staggered between two hydrogens. If you perform a single rotation of 120°, you will end up with an equivalent rotational form. At 60°, you will have two H-H eclipsed interactions and one H-I eclipsed interaction. Recall that there are no CH3 groups to be eclipsed or gauche. You know each H-H eclipsed is 4 kJ/mol (8 kJ/mol total) and the reported barrier is 14 kJ/mol. Therefore the H-I eclipsed interaction must be 6 kJ/mol, (14-8 = 6).

thank you so much! It makes perfect sense now

lol sure glad I could help

I'm in Organic chem I and I wish it had more math like general chem, the general structures you have to learn are very tedious. Thankfully there are a limited amount of functional groups to know, very easy to make mistakes that you look back on as silly.

I find it to be more imagination and making 3D images in your mind, sort of.