Question

So exactly, does surface area of the molecule (referring to IMF strength really) mean higher or lower MP/BP?

I was earlier told that the least compact, least branched, and most linear molecules have greater MP but I just came across an example rather against that..

Answer 1

Let me just post the question, just a sec..

Answer 2

Which of the following substances has the highest melting point?

Answer 3

A -

Answer 4

B -

Answer 5

C -

Answer 6

D -

Answer 7

I knew A and B were off the list because the other two options have greater bond strength.

I personally chose C because it was linear and the triple bond between the C and O.

Turns out it is D.

Answer 8

I knew A and B were off the list because the other two options have greater bond strength.

I personally chose C because it was linear and the triple bond between the C and O.

Turns out it is D.

Answer 9

My question is, does this mean ringed structures have stronger dispersion forces?

Answer 10

didn't trust myself to give a good answer on this so I looked it up

"London Dispersion Forces and Cycloalkanes
Although alkanes are similar to cycloalkanes, they have higher London Dispersion forces because the ring shape allows for a greater area of contact. Ring strain also causes certain cylcoalkanes to be more reactive. London Dispersion Forces are the attractive or repulsive forces between molecules or between parts of the same molecule. For cycloalkanes, London dispersion forces refer to the repulsive forces between the molecules that cause ring strain."

source: https://chem.libretexts.org/Bookshelves/Organic_Chemistry/Supplemental_Modules_(Organic_Chemistry)/Alkanes/Properties_of_Alkanes/Cycloalkanes/Physical_Properties_of_Cycloalkanes

Answer 11

Ah thank you for responding, I'll check it out.