3F.1 C

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Lauren Haight 1E
Posts: 73
Joined: Wed Sep 18, 2019 12:15 am
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3F.1 C

Postby Lauren Haight 1E » Tue Nov 19, 2019 3:40 pm

Why does CHI3 have a higher melting point than CHF3? I would guess that dipoles are stronger in CHF3 due to F's high electronegativity, but this is not the case. Can someone please explain?

Lauren Haight 1E
Posts: 73
Joined: Wed Sep 18, 2019 12:15 am
Been upvoted: 1 time

Re: 3F.1 C

Postby Lauren Haight 1E » Tue Nov 19, 2019 3:43 pm

Because I is larger than F, does molecular size trump intermolecular interaction when determining melting points?

Mashkinadze_1D
Posts: 87
Joined: Sat Aug 24, 2019 12:15 am

Re: 3F.1 C

Postby Mashkinadze_1D » Tue Nov 19, 2019 3:53 pm

The induced-dipole-induced-dipole forces in the molecule with iodine are so much higher than the one with fluorine that it cancels out the stronger dipole due to the large difference in the amount of electrons between the two elements. In certain cases a stronger dipole moment would create stronger IM forces, but when the amount of electrons is so drastically large the increased polarity is outweighed. Hope this helps!

Aman Sankineni 2L
Posts: 103
Joined: Fri Aug 30, 2019 12:17 am

Re: 3F.1 C

Postby Aman Sankineni 2L » Tue Nov 19, 2019 3:55 pm

Molecular size determines intermolecular interaction strength. Since Iodine is a larger atom than Fluorine, it has stronger intermolecular strength and therefore a higher melting point.


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