7th edition 3F.15 polarity and boiling points

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Nawaphan Watanasirisuk 3B
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Joined: Tue Nov 28, 2017 3:03 am

7th edition 3F.15 polarity and boiling points

Postby Nawaphan Watanasirisuk 3B » Sat Nov 24, 2018 10:51 pm

The book asks to explain why AsF3 has significantly higher boiling point than AsF5 and in the solution its because AsF3 is a polar molecule. What makes AsF3 polar? Is it because the lone pair pushes the 3 F bonds down and so the vectors don't cancel out whereas in AsF5 all 5 bonds are spread out around As so the vectors there cancel out making AsF5 non polar?

janeane Kim4G
Posts: 31
Joined: Fri Sep 28, 2018 12:28 am

Re: 7th edition 3F.15 polarity and boiling points

Postby janeane Kim4G » Sun Nov 25, 2018 2:25 am

You’re right, in this case the lone pair will lead to an uneven electron distribution, leading to polarity. AsF5 on the other hand has no lone pairs, therefore the charge and electron density is equally distributed, making it harder to break up the bonds.


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