3F.19

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Alexa Mugol 3I
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Joined: Sat Aug 17, 2019 12:17 am

3F.19

Postby Alexa Mugol 3I » Tue Nov 19, 2019 9:50 pm

In 3F.19 b), it says that H bonding in water causes the molecules to be held together more tightly than in diethyl ether. But if there are two lone pairs on the central O atom, then doesn't diethyl ether have H bonding too? What makes the H bonding in water stronger than the H bonding in diethyl ether?

Ryan Narisma 4G
Posts: 88
Joined: Fri Aug 30, 2019 12:18 am

Re: 3F.19

Postby Ryan Narisma 4G » Tue Nov 19, 2019 9:57 pm

Hello Alexa Mugol 3I! To answer your question, diethyl ether is not capable of hydrogen bonding. When you draw the lewis structure of diethyl ether, the Oxygen atom is in the center of the diagram and is not connected to any hydrogens. If the oxygen were covalently bonded to a hydrogen, then diethyl ether would exhibit hydrogen bonding. However, this is not the case. The strongest intermolecular force that diethyl ether can have is dipole-dipole interactions, which are weaker than the hydrogen bonding exhibited by water. Because diethyl ether has weaker intermolecular forces, it requires less energy to break the attraction between two diethyl ether molecules. Therefore, it has a higher vapor pressure than water because more of the diethyl ether molecules can be broken off and enter the gas state. I hope this helps!

Anisha Chandra 1K
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Joined: Thu Jul 11, 2019 12:17 am

Re: 3F.19

Postby Anisha Chandra 1K » Wed Nov 20, 2019 10:53 am

Just to clarify, does high vapor pressure indicate higher boiling point?

Alexa Mugol 3I
Posts: 54
Joined: Sat Aug 17, 2019 12:17 am

Re: 3F.19

Postby Alexa Mugol 3I » Wed Nov 20, 2019 4:13 pm

Anisha Chandra 4H wrote:Just to clarify, does high vapor pressure indicate higher boiling point?

The stronger the intermolecular forces, the lower the vapor pressure and the higher the boiling point :)

sarahsalama2E
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Joined: Fri Aug 30, 2019 12:16 am

Re: 3F.19

Postby sarahsalama2E » Wed Nov 20, 2019 4:53 pm

doesn't the strength of london disperson forces take priority over dipole-dipole forces when determining which compound has a higher boiling point?

Diana_Diep2I
Posts: 106
Joined: Sat Aug 17, 2019 12:17 am

Re: 3F.19

Postby Diana_Diep2I » Wed Nov 20, 2019 6:56 pm

sarahsalama1G wrote:doesn't the strength of london disperson forces take priority over dipole-dipole forces when determining which compound has a higher boiling point?

Not really. You have to first compare IMF strength before comparing different London dispersion force factors like size or number of electrons. In this case, diethyl ether has no actual hydrogen bonds while H2O has hydrogen bonds. We can assume that we aren't considering potential hydrogen bonding sites in this problem. Diethyl ether is nonpolar and participates in London dispersion interaction while H2O is polar and participates in hydrogen bonding. Therefore H2O has a higher boiling point.


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