Molecule Size and Melting Points

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AChoudhry_1L
Posts: 55
Joined: Sat Sep 07, 2019 12:17 am

Molecule Size and Melting Points

Postby AChoudhry_1L » Wed Nov 13, 2019 9:10 am

Is it true that bigger molecules have higher melting points? Is this the thought process behind figuring out which would have a higher melting point between CHI3 and CHF3?

Chem_Mod
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Re: Molecule Size and Melting Points

Postby Chem_Mod » Wed Nov 13, 2019 9:13 am

Yes, if molecules have the same general structure, then the bigger one or one with more molecular weight will have the higher boiling or melting point.

lauraxie2e
Posts: 87
Joined: Fri Aug 09, 2019 12:17 am

Re: Molecule Size and Melting Points

Postby lauraxie2e » Wed Nov 13, 2019 9:19 am

Yes because usually molecules that weigh more have stronger forces so they will have higher MP/BP

Michael Nguyen 1E
Posts: 96
Joined: Sat Aug 17, 2019 12:17 am

Re: Molecule Size and Melting Points

Postby Michael Nguyen 1E » Wed Nov 13, 2019 9:27 am

Bigger molecules have larger electron clouds, which make them more polarizable. This will lead to stronger dipole moments between the molecules and stronger attractive forces. This will increase the melting and boiling points of the compounds.

Natalie Nartz 4F
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Joined: Thu Jul 11, 2019 12:17 am

Re: Molecule Size and Melting Points

Postby Natalie Nartz 4F » Wed Nov 13, 2019 10:01 am

This is true, as molecules increase in size, their boiling point increases. This is because large molecules have more electrons and nuclei which creates stronger intramolecular forces like van der waals which then increases the boiling point.

Avnita C_4B
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Re: Molecule Size and Melting Points

Postby Avnita C_4B » Wed Nov 13, 2019 11:22 am

When the molecules has similar structures, we look at the size to see which one has a higher boiling point. As the size increases, the boiling point increases as well.

Zoya Mulji 1K
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Joined: Thu Jul 11, 2019 12:15 am

Re: Molecule Size and Melting Points

Postby Zoya Mulji 1K » Fri Nov 15, 2019 5:10 pm

Bigger molecules do have higher boiling points but the shape of the molecule also can influence boiling point. For example, molecules with the same molecular formula but different shapes (branched vs. linear) can have different BPs.


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