Chemistry is COOL!

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#1 Post by **gator** » Sun Jun 03, 2007 8:18 pm

http://www.youtube.com/watch?v=jwRro4mXfKs

Really a 'cool' video ... any chemical engineers here can explain why it happens? Is it because of supersaturation?

Bonus marks for people who can tell me what song is playing in the background ...

furrycute · #2 Post by **furrycute** » Sun Jun 03, 2007 10:00 pm

It probably is because of super saturation. When the solution is super saturated, even a single extra molecule (theoretically) can bring the whole solute out of solution.

#3 Post by **Kyocera** » Sun Jun 03, 2007 10:15 pm

You sure their not making meth

brentpresley · #4 Post by **brentpresley** » Mon Jun 04, 2007 7:19 am

Yes, that is a supersaturation crystallization.

(and yes, I have a Chem degree).

#5 Post by **gator** » Mon Jun 04, 2007 1:12 pm

Thanks Brent ... one more question for you: If this is supersaturation, it should work with any salt (like NaCl) right? Or is this some sodium acetate specific property? I have forgotten most of my high school chemistry, so please be gentle and don't kill me if this question is stupid

Temetka · #6 Post by **Temetka** » Mon Jun 04, 2007 1:15 pm

So why does touching it set it off then?

furrycute · #7 Post by **furrycute** » Mon Jun 04, 2007 1:18 pm

Your hands contain lots of impurities (microscopic). By touching the supersaturated solution, those microscopic impurities on your hands get transferred to the solution.

#8 Post by **gator** » Mon Jun 04, 2007 1:19 pm

Temetka, this is a good read:
http://en.wikipedia.org/wiki/Supersaturation

From the article:

Small particles (seeds) can trigger the separation of the dissolved material from the solvent or condensation of the vapor. In the solid form these seeds can lead to the formation of crystallites or even large single crystals. Supersaturation is a measure of the deviation of a dissolved sodium chloride crystal from its equilibrium value.

Purcy · #9 Post by **Purcy** » Mon Jun 04, 2007 1:52 pm

gator wrote: I have forgotten most of my high school chemistry, so please be gentle and don't kill me if this question is stupid

That's not a stupid question, and if anyone thinks YOU'RE stupid, I'd hate to know what they think of me

#10 Post by **gator** » Mon Jun 04, 2007 2:09 pm

Purcy wrote: That's not a stupid question, and if anyone thinks YOU'RE stupid, I'd hate to know what they think of me

Pattye, you over-estimate my skull capacity!

brentpresley · #11 Post by **brentpresley** » Mon Jun 04, 2007 4:57 pm

gator wrote:Thanks Brent ... one more question for you: If this is supersaturation, it should work with any salt (like NaCl) right? Or is this some sodium acetate specific property? I have forgotten most of my high school chemistry, so please be gentle and don't kill me if this question is stupid

Different salts have different concentrations that they must reach to become super-saturated. Sugar, sodium acetate, etc. require much lower concentrations than small molecules (i.e. 2 atoms) like NaCl.

Sodium Acetate is also a pretty extreme example. Most super-saturated solutions do not crystalize nearly as quickly. Hence the WOW FACTOR.

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