melting point

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bgiorgi_3A
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Joined: Wed Sep 30, 2020 9:50 pm

melting point

Postby bgiorgi_3A » Tue Nov 10, 2020 10:47 am

Suggest, giving reasons, which substance in each of the following pairs is likely to have the higher normal melting point. C2H5OC2H5 (diethyl ether) or C4H9OH (butanol). Hey guys! So the answer to this is butanol, and I was wondering if the reason was because the structure of butanol is polar whereas the structure of diethyl ether is nonpolar?
Last edited by bgiorgi_3A on Tue Nov 10, 2020 8:49 pm, edited 1 time in total.

Andrew Wang 1C
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Re: melting point

Postby Andrew Wang 1C » Tue Nov 10, 2020 10:53 am

Yes, I believe that is the case. Since diethyl ether is nonpolar, it only has induced dipole-induced dipole interactions (LDF) between its molecules. Butanol also has LDF, but will also have dipole-dipole interactions because it is polar. So because of this extra interaction, it requires more energy to melt and thus has a higher melting point.

Jasmin Kumar 1G
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Re: melting point

Postby Jasmin Kumar 1G » Tue Nov 10, 2020 11:23 am

My TA explained it in that butanol has an alcohol group that can have hydrogen bonding while diethyl ether does not, so butanol would have a higher melting point.

EnricoArambulo3H
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Re: melting point

Postby EnricoArambulo3H » Tue Nov 10, 2020 11:50 am

While both molecules exhibit London Dispersion Forces, butanol has hydrogen bonding capabilities due to the -OH group at the end of the molecule. The strength of a hydrogen bond is higher than an ion-dipole interaction and lower than an ion-ion interaction. Thus, hydrogen bonding would be stronger than London Dispersion Forces, and butanol would have a higher melting point.

Anirudh Mahadev 1G
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Re: melting point

Postby Anirudh Mahadev 1G » Tue Nov 10, 2020 12:20 pm

EnricoArambulo1B wrote:While both molecules exhibit London Dispersion Forces, butanol has hydrogen bonding capabilities due to the -OH group at the end of the molecule. The strength of a hydrogen bond is higher than an ion-dipole interaction and lower than an ion-ion interaction. Thus, hydrogen bonding would be stronger than London Dispersion Forces, and butanol would have a higher melting point.

I agree, since hydrogen bonding is the strongest form of IMFs, more energy is needed to break the bonds between molecules and convert the substance from a solid to a liquid.


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