Class question: polarizability and boiling point

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Anna De Schutter - 1A
Posts: 66
Joined: Wed Feb 21, 2018 3:01 am

Class question: polarizability and boiling point

Postby Anna De Schutter - 1A » Mon May 28, 2018 3:00 pm

Hi!

In class we talked about how the interaction potential energy for induced dipole - induced dipole interactions is proportional to (polarizability 1 * polarizability 2)/distance^6

We also said that the polarizability depends on the size of the atom and the number of electrons, with an increase in the number of electrons leading to an increase in polarizability. Why is that? We then ranked F2, Cl2, CH4 and CCl4 in order of increasing boiling point; with F2 and Cl2 being gases at room temperature, CH4 boiling at -161.5 degrees and CCl4 boiling at +77 degrees. To explain why CH4 has a lower boiling point than CCl4 we said that was because its polarizability was lower. I'm a bit confused though, how does polarizability affect the boiling point of a molecule?

Thank you!
Anna De Schutter - section 1A

Katarina Ho -1B
Posts: 29
Joined: Fri Apr 06, 2018 11:03 am

Re: Class question: polarizability and boiling point

Postby Katarina Ho -1B » Mon May 28, 2018 11:03 pm

Hi! If polarizability is lower than that means that the strength of the interacting molecular bond is also a lot easier to break. If there bonds are easier to break then you will not have to reach a very high temperature to break them hence them having a lower boiling point.

Anna De Schutter - 1A
Posts: 66
Joined: Wed Feb 21, 2018 3:01 am

Re: Class question: polarizability and boiling point

Postby Anna De Schutter - 1A » Tue May 29, 2018 8:17 am

That makes a lot of sense, thank you! :)


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