Naked Science Forum

Non Life Sciences => Chemistry => Topic started by: thedoc on 24/12/2013 18:26:55

Title: Which has a lower boiling point, liquid hydrogen or liquid helium?
Post by: thedoc on 24/12/2013 18:26:55

Nina asked the Naked Scientists:

   

I was wondering which had a lower boiling point, liquid hydrogen or liquid helium?



I think I have read that helium has a lower boiling point, but could you explain why?



Thank you!



What do you think?

Title: Re: Which has a lower boiling point, liquid hydrogen or liquid helium?
Post by: djandersonza on 07/12/2013 19:13:38

Helium has a lower boiling point because of weaker van de Waals Forces

Title: Re: Which has a lower boiling point, liquid hydrogen or liquid helium?
Post by: chiralSPO on 09/12/2013 20:36:49

Helium has a lower boiling point because it is a single spherical atom. It has very little surface area, and is not very polarizable. Elemental hydrogen exists as a diatomic molecule (H2). Even though it has a lower mass than helium, H2 has the same number of electrons, and they are distributed over a larger space in the linear (not spherical) molecule. These electrons are more free to move within the molecule, which means it is polarizable. This difference in polarizability is responsible for the difference in strength of intermolecular forces.

Title: Hear the answer to this question on our show
Post by: thedoc on 24/12/2013 21:24:05

We discussed this question on our  show
Transcript to follow...

Click to visit the show page for the podcast in which this question is answered. (http://www.thenakedscientists.com/HTML/podcasts/naked-scientists/show/20131224/) Alternatively, [chapter podcast=1000582 track=13.12.24/Naked_Scientists_Show_13.12.24_1001784.mp3](https://www.thenakedscientists.com/forum/proxy.php?request=http%3A%2F%2Fwww.thenakedscientists.com%2FHTML%2Ftypo3conf%2Fext%2Fnaksci_podcast%2Fgnome-settings-sound.gif&hash=f2b0d108dc173aeaa367f8db2e2171bd) listen to the answer now[/chapter] or [download as MP3] (http://nakeddiscovery.com/downloads/split_individual/13.12.24/Naked_Scientists_Show_13.12.24_1001784.mp3)