Van Der Waal vs Hydrogen Bons

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Van Der Waal vs Hydrogen Bons

Postby Jordan_Wesson_2J » Thu Nov 08, 2018 11:09 am

I was taught that in general Van Der Waals and usually weaker than hydrogen bonds but at some point can become stronger if the size of the molecules is big enough. I was wondering if this was correct, and if so, how would you find out when it becomes stronger?

Tarika Gujral 1K
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Re: Van Der Waal vs Hydrogen Bons

Postby Tarika Gujral 1K » Thu Nov 08, 2018 12:12 pm

Hydrogen bonding and Van der Waal forces are both intermolecular forces.
VDW forces are present in all molecules
H-bonding is typically characterized by H-NOF bonds

From my understanding, because VDW forces is a bond between induced dipoles (which arise from a “temporary” dipole formation), hydrogen bonds are always stronger, regardless of size of molecule.

Matthew Tran 1H
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Re: Van Der Waal vs Hydrogen Bons

Postby Matthew Tran 1H » Thu Nov 08, 2018 12:22 pm

It is important to note that hydrogen bonds are just a special type of polar bonds that are stronger because of the large difference in electronegativity between hydrogen and oxygen, nitrogen, and fluorine. Thus, hydrogen bonds result from a permanent dipole whereas van der Waals forces are induced dipole-induced dipole. Hydrogen bonds are much stronger than van der Waal's forces (-20kJ/mol vs. -2kJ/mol).

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