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Author Topic: What are van der Waals attractions?  (Read 4072 times)

Offline bashir2008

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What are van der Waals attractions?
« on: 10/04/2009 14:27:38 »
Dear all

1- I want to understand more about Van der Waals force . how does it happen and what is the importance of it... could you please support your answer with some drawings as well?
2- What is the drag force ?

Hope there are some people who can assist me

Thanks
« Last Edit: 12/04/2009 12:20:28 by chris »


 

Offline Chemistry4me

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Re: What are van der Waals attractions?
« Reply #1 on: 11/04/2009 03:55:58 »
Drag force is forces that oppose the relative motion of an object through a fluid (a liquid or gas).

http://en.wikipedia.org/wiki/Air_resistance
 

Offline Chemistry4me

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Offline Raghavendra

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Re: What are van der Waals attractions?
« Reply #3 on: 12/04/2009 09:08:32 »
Vander  bonding easy to learn
 

Offline Chemistry4me

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Re: What are van der Waals attractions?
« Reply #4 on: 12/04/2009 11:57:20 »
Obviously it is easier to learn it than to spell it? :)
 

Offline Raghavendra

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What are van der Waals attractions?
« Reply #5 on: 13/04/2009 07:22:49 »
LOL  ;D ;D Ya you are right
 

Offline bashir2008

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What are van der Waals attractions?
« Reply #6 on: 13/04/2009 11:03:45 »
Thanks for answering the question
 

Offline lightarrow

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What are van der Waals attractions?
« Reply #7 on: 13/04/2009 14:14:54 »
For van der Waals:

http://www.chemguide.co.uk/atoms/bonding/vdw.html

Separate page for hydrogen bonding:

http://www.chemguide.co.uk/atoms/bonding/hbond.html#top
Just for curiosity, why did you link the page of hydrogen bonding?
 

Offline Chemistry4me

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What are van der Waals attractions?
« Reply #8 on: 13/04/2009 14:16:42 »
In a textbook it (hydrogen-bonding) went under the same heading (as instantaneous dipole-dipole, permanent dipole-dipole etc...) of: van der Waals forces.
 

Offline lightarrow

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What are van der Waals attractions?
« Reply #9 on: 13/04/2009 14:27:11 »
In a textbook it (hydrogen-bonding) went under the same heading (as instantaneous dipole-dipole, permanent dipole-dipole etc...) of: van der Waals forces.
Ok, you can throw away that text :).  They are completely different things.
 

Offline Chemistry4me

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What are van der Waals attractions?
« Reply #10 on: 13/04/2009 14:30:50 »
Oh really? ??? That'll mean...have I been learning the wrong stuff? :)
So they are a completely different form of intermolecular attraction?
 

Offline lightarrow

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What are van der Waals attractions?
« Reply #11 on: 13/04/2009 14:36:15 »
Oh really? ??? That'll mean...have I been learning the wrong stuff? :)
So they are a completely different form of intermolecular attraction?
Yes:
Van der Waals interactions are much weaker (per unit surface of molecules) than hydrogen bonding and, furthermore, they are dipole interactions due to instantaneous dipole induction, whyle hydrogen bonding are due to permanent dipoles; furthermore hydrogen bonding is directional (just think about ice' structure), Van der Waals is not.
« Last Edit: 13/04/2009 14:38:10 by lightarrow »
 

Offline Chemistry4me

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What are van der Waals attractions?
« Reply #12 on: 13/04/2009 14:46:31 »
Okay, I see what you mean. Cheers lightarrow.
 

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What are van der Waals attractions?
« Reply #12 on: 13/04/2009 14:46:31 »

 

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