May 11, 2021, 07:35:39 PM
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Topic: Why does water have a greater polarity than ethanol?  (Read 182 times)

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Offline BIOKID123

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Why does water have a greater polarity than ethanol?
« on: May 02, 2021, 12:48:34 AM »
Hello,
I understand that water has intermolecular forces such as hydrogen bonding, so it's really hard to separate the molecules. And, ethanol also has hydrogen bonding, but london dispersion force as well. Why is water more polar than ethanol?
is it because ethanol also has a london dispersion force, so part of the bond is weak in attraction?

edit: water also has London dispersion force (LDF), but I think since ethanol is mostly comprised of LDF, it is weak in attraction with other ethanol molecules?
« Last Edit: May 02, 2021, 01:20:35 AM by BIOKID123 »

Offline Borek

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Re: Why does water have a greater polarity than ethanol?
« Reply #1 on: May 02, 2021, 03:25:43 AM »
You got it reversed.

It is not dominating interactions between molecules that tells us whether the molecule is polar, or not, it is whether the molecule is polar or nor not that tells us what kind of intermolecular interaction to expect.

In general polar molecules are either dipoles, or contain several dipoles: https://en.wikipedia.org/wiki/Chemical_polarity

And this statement:

ethanol is mostly comprised of LDF

is simply off. Molecules don't "comprise of forces", they comprise of atoms. Forces are how they interact with other molecules, and these interaction are always combinations of forces we classify as different types.
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Offline BIOKID123

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Re: Why does water have a greater polarity than ethanol?
« Reply #2 on: May 02, 2021, 05:00:05 AM »
Oh okay, thank you. By the way, sorry about the wording. I am severely tired at the moment, I meant ethanol mainly uses LDP, not that is created by it. Anyways thanks for the help.


Offline Orcio_Dojek

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Re: Why does water have a greater polarity than ethanol?
« Reply #3 on: Today at 05:03:18 PM »
Quote
Why does water have a greater polarity than ethanol?
Did you consider the difference in polarity of O-CH3 and O-H bond ?

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