jgourlay
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Interesting distallation result I can't explain
Back to the kiddie chemistry.....
My four year old has decided SHE wants to learn science just like her big brother. So I decided to show her the first demonstration I did for him.
You all may not remember, that was the one where the alchohol lamp cracked and sprayed flaming alchohol all over the homeschool materials on the
dining room table? Yeah....
Anyhoo, I have better equipment now: boiling flasks, butane heater, proper stands....
You know you have a lot of kids when you decide to use Chopin in your experiments because you simply have no time to drink anymore. Chopin goes into
the boiling flask and on goes the heat. Remember, the task here is to show two boiling points and that there are two "materials" in the "clear"
liquid.
It boils. I hold a lighter under the glass tube and as expected it sputters a bit and then ignites. So far so good. After some time of watching the
flame, she decides that's not interesting anymore and heads over to the jungle gym.
To get here back, I decide to show here how the boiling flask can "drink from a straw" just like she can. So I get a glass of cold water, and stick
it under the glass tube. She thinks it's neat because you can see the alchohol vapor immediately liquify into the cold water. I turn off the heat
and shortly thereafter the water starts to "suck" up the tube.
When the cold water hits the boiling flask there is a rapid temperature drop as expected and the flask really starts to suck water.
And here is where it get's interesting. It's sucking water fast--fast enough to shake the apparatus AND SIMULTANEOUSLY the liquid in the flask is
BOILING. And I mean, a ROLLING boil with huge splashy bubbles. This lasts for a good 5 seconds and is a huge hit--even the two year old starts
jumping up and down squealing.
But I am at a total loss to explain the "boil" simultaneous to the "pressure drop".
Also, briefly, once the boil stopped, the whole mixture went milky then cleared up. What gives?
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hissingnoise
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It's unlikely you used poor Frederick, so Chopin must be a liquid measure (looked it up!), but I was seriously nonplussed there for a while.
I think your liquid boiled because pressure was reduced---residual heat was enough to boil the liquid at low pressure.
the milkiness might be poor mixing of liquids of different density, och aye. . .
[Edited on 30-3-2009 by hissingnoise]
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jgourlay
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So it was the alchohol boiling out? It was wild because in addition to all that, the "air" on top of the liquid formed "fog" during the process.
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hissingnoise
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The other definition I got for Chopin was a Scottish quart, hence the "och aye" bit. . .
The fog BTW, would be precipitation of liquid from saturated air caused by the lowered pressure.
Met Office stuff. . .
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jgourlay
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Cool, so there was boiling and precipitation all at once. Love that!
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jgourlay
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Sorry, "Chopin" is a brand of vodka! I didn't know it was also a unit of measure.
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hissingnoise
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Vodka! Of course, how absentminded of me. . .
Cheersh!
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watson.fawkes
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The
milkiness is an emulsion. I would have to guess that's its all the stuff in the vodka that's neither ethanol nor water. It's soluble (because the
emulsion disappeared), but not instantly so (slow reaction kinetics). Therefore it forms a temporary emulsion. I would guess that it doesn't form with
just ethanol and water.
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PHILOU Zrealone
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Quote: Originally posted by watson.fawkes  | | The
milkiness is an emulsion. I would have to guess that's its all the stuff in the vodka that's neither ethanol nor water. It's soluble (because the
emulsion disappeared), but not instantly so (slow reaction kinetics). Therefore it forms a temporary emulsion. I would guess that it doesn't form with
just ethanol and water. |
Could be microbubbles from the cavitation...this happens sometimes with tap water just out of the tap into your glas...sudden pressure drop -->
gassing out
PH Z (PHILOU Zrealone)
"Physic is all what never works; Chemistry is all what stinks and explodes!"-"Life that deadly disease, sexually transmitted."(W.Allen)
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hissingnoise
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Yes w.f, in hindsight, it's obviously not the normal turbidity associated with mixing EtOH and water.
Tiny air bubbles being forced out of the water (again) by the lowered pressure would have been another theory. . .
PHILOU's, beaten me to it! Oh well. . .
[Edited on 31-3-2009 by hissingnoise]
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