Jump to content

Intermolecular forces

Recommended Posts

1. Why does CH3COOH have a higher boiling point than CH3CH2OH, don't they both form hydrogen bonding, what else is a determining factor? Is it the molar mass as the greater the molar mass the more electrons and the increased polarisability so the stronger the London dispersion forces?

2. What intermolecular forces does van der Waals' forces cover (I get different interpretations from different sources)?

Share this post


Link to post
Share on other sites

For the IB, van der Waals forces include London dispersion forces and dipole-dipole attractions, but not hydrogen bonding. 

There's a good explanation of the higher boiling point of carboxylic acids here:

http://www.chemguide.co.uk/organicprops/acids/background.html

In a pure carboxylic acid, hydrogen bonding can occur between two molecules of acid to produce a dimer.

dimer.gif

This immediately doubles the size of the molecule and so increases the van der Waals dispersion forces between one of these dimers and its neighbours - resulting in a high boiling point.

Edited by Msj Chem
  • Like 3

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

×

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.