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Author Topic: What is happening at a nucleation site?  (Read 10727 times)

Offline chris

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What is happening at a nucleation site?
« on: 26/03/2007 10:11:18 »
We often speak of nucleation sites where dissolved gases, like the CO2 in a bottle of fizzy drink, form streams of rising bubbles.

But, at a molecular level, what is actually going on at a nucleation site? What makes these rough or pointy locations favourable centres for dissolved gases to form bubbles?

Chris


 

paul.fr

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What is happening at a nucleation site?
« Reply #1 on: 26/03/2007 10:19:48 »
Not too sue if this is what you are asking, Chris. but i think it is something to do with enthalpy loss. I struggle to remember more, may be after a sleep!
« Last Edit: 26/03/2007 10:21:44 by paul.fr »
 

another_someone

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What is happening at a nucleation site?
« Reply #2 on: 26/03/2007 15:18:14 »
My guess is that it has more to do with intermolecular electrical forces.

I would guess that gasses (or anything else) are held in solution by fairly week and diffuse electrical forces, and having something that can come along and break up the pattern of the electrical forces that hole the solute in solution will allow the solute to break free of those forces.
 

paul.fr

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What is happening at a nucleation site?
« Reply #3 on: 26/03/2007 17:56:04 »
Possibly we may be both in the right direstion, George. After all are is more than one type of nucleation sites. energy playing a part, but i can no recall the whys.
 

paul.fr

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What is happening at a nucleation site?
« Reply #4 on: 12/04/2007 23:21:47 »
a nucleation site can be thought of (in the case of crystallization) as an actual physical location where energy is drawn off more easily - due to the greater surface to volume ratio (high surface area) of the site. In the case of vaporization, the nucleation site can be thought of as an actual physical location where temperatures can be locally higher, and where energy transfer is more efficient - again because of the high surface area.
 

Offline Seany

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What is happening at a nucleation site?
« Reply #5 on: 12/04/2007 23:40:47 »
Yes.. Just watch this video which I saw a year back because my friend told me about it..

http://gprime.net/video.php/planevsconcretewall
 

Offline ukmicky

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What is happening at a nucleation site?
« Reply #6 on: 13/04/2007 02:37:30 »
Yeah thats a wicked video seany ,i saw it about ten years ago i think it even came up in a topic on this forum once
 

Offline anthony

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What is happening at a nucleation site?
« Reply #7 on: 13/04/2007 10:21:17 »
The answer will be connected to surface tension. Small bubbles have a high curvature and so a higher energy related to the surface. The roughness of the surface creates spots where the curvature can be reduced and surface energy of the bubble can be decreased. Bubbles perferentially form and grow on these locations.
 

Offline Seany

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What is happening at a nucleation site?
« Reply #8 on: 13/04/2007 10:47:52 »
You've been on this forum for 10 years micky? :o

Oh, btw that doesn't mean you're old :P Just that it was a long time ;)
 

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What is happening at a nucleation site?
« Reply #8 on: 13/04/2007 10:47:52 »

 

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