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Rachel Yu 1G
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Joined: Fri Aug 09, 2019 12:15 am


Postby Rachel Yu 1G » Mon Nov 11, 2019 1:51 pm

The question asks if CHI3 or CHF3 has a higher normal melting point. The solution manual says the answer is CHI3 because is has greater London dispersion forces but I thought CHF3 was polar/had dipole interactions. Why does CHI3 have stronger intermolecular interactions?

Parker Smith
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Joined: Thu Jul 25, 2019 12:15 am

Re: 3F5C

Postby Parker Smith » Mon Nov 11, 2019 2:16 pm

I would also think CHF3 has a higher melting point than CHI3, since the C-F bond is a closer and therefore stronger attraction than the C-I bond. The solution book could be incorrect?? However I concur with your statement.

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Re: 3F5C

Postby JOtomo1F » Mon Nov 11, 2019 3:22 pm

I was also confused about this question and was wondering the same thing.

Hailey Kim 4G
Posts: 110
Joined: Sat Jul 20, 2019 12:16 am

Re: 3F5C

Postby Hailey Kim 4G » Tue Nov 12, 2019 9:02 pm

Both CHI3 and CHF3 are polar and have London Dispersion forces. However, CHI3 has a stronger London Dispersion force because CHI3 is a much bigger molecule than CHF3. Iodine has a greater molar mass than fluorine, and the bigger the atom, the stronger the intermolecular force. This would then require a higher boiling point.

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