Humor Depressurization of (super?)cooled cola

[Urwumpe]

Fascinating: Depressuring cola chilled to -3.0°C (opening the bottle) results in the rapid formation of tiny ice balls on the surface. Continue further research, maybe this can revolutionize spaceflight. :lol:

 

[RisingFury]

Actually... that IS very interesting! I wonder what causes it...

 

[tblaxland]

Fascinating: Depressuring cola chilled to -3.0°C (opening the bottle) results in the rapid formation of tiny ice balls on the surface.

Very interesting. By surface, do you mean at the cola/air interface within the neck of the bottle, or on the surface of the bottle itself. Also, what were the ambient air conditions like at the time of conducting this experiment (temp, humidity)?

 

[ex-orbinaut]

"Houston reports successful cola bottle separation..."

I might be wrong, but at first glance I would assume that, under and because of pressure, carbonated cola is supercooled (at -3 degrees); ie, still liquid below its "normal" ambient freeing point. Upon being decompressed, latent heat is allowed to dissipate, cools the surface of the bottle (is it plastic or glass?) and causes freezing of ambient moisture on the surface. That would be my guess... :shrug:

Edit: Have you ever used a modelling airbrush with those pressurized canisters? A similar thing happens with them.

 

[Urwumpe]

Very interesting. By surface, do you mean at the cola/air interface within the neck of the bottle, or on the surface of the bottle itself.

Only the air/liquid interface, I had not been able to spot other such ice spheres on the wall.

Also, what were the ambient air conditions like at the time of conducting this experiment (temp, humidity)?

Room temperature, about 40% relative humidity (it isn't especially dry here). Bottle taken out of the trunk of my car at about -3°C.

Was already established that Cola doesn't freeze at -8°C (contrary to bottles of soda), which is why I often leave the stuff inside the car over night.

 

[tblaxland]

I might be wrong, but at first glance I would assume that, under and because of pressure, carbonated cola is supercooled (at -3 degrees); ie, still liquid below its "normal" ambient freeing point. Upon being decompressed, latent heat is allowed to dissipate, cools the surface of the bottle (is it plastic or glass?) and causes freezing of ambient moisture on the surface. That would be my guess...

That was my thinking too, and explains why the ice forms only at the air/liquid interface. With a glass or metal bottle you might even expect to see some freezing of the condensation on the outside of the bottle upon de-pressurisation. I'm guessing the cola is not technically supercooled at -3°C since you would expect to see some slush form within the liquid when it is depressurised: http://en.wikipedia.org/wiki/Supercooling#Applications

 

[Andy44]

What brand and flavor of cola was this? Mythbusters tested the Diet Coke and Mentos myth and found it only works with Diet Coke.

 

[Urwumpe]

What brand and flavor of cola was this? Mythbusters tested the Diet Coke and Mentos myth and found it only works with Diet Coke.

I ain't gonna drink diet coke...standard Coca Cola, in 1.25 l PET bottle.

 

[Eccentrus]

I think this is related to superheating, take a glass of pure water (the distilled one) put it in microwave long enough that the usual water would be boiling, and then, without taking the glass out, put a fork in it, and poof, the whole glass of water would become vapour instantenously. The Answer would lie in the superstructure of water liquid and water ice.

 

[foxtrot]

It must get hot in space if they need cola that cold!

lol Joking! :lol:

 

[tblaxland]

I think this is related to superheating, take a glass of pure water (the distilled one) put it in microwave long enough that the usual water would be boiling, and then, without taking the glass out, put a fork in it, and poof, the whole glass of water would become vapour instantenously. The Answer would lie in the superstructure of water liquid and water ice.

Sounds like a dangerous experiment...

Why wouldn't distilled water boil in a microwave, and why would the fork make it boil?

 

[Eccentrus]

well ask the mythbusters for that (they actually put that in an episode) but to put a short answer, because a totally unpoluted water have stronger bonds between each other, putting a fork, or salt, or any other materials into it breaks the bonds so much suddenly it boils, or super-boils (take a note that boiling is the moment when the partial pressure of water is equal to the pressure of the ambient atmosphere)

 

[Quick_Nick]

VERY dangerous indeed.
Check out 1:12 to 1:17 at least.

 

[PhantomCruiser]

One of the worst scoldings I ever gave my daughter was from boiling water in a microwave and pouring hot chocolate power over it. I had to show here why such a thing was dangerous.
I wish I could see that clip, but they block youtube here at work. (rat bast*rds)

 

[RisingFury]

I might be wrong, but at first glance I would assume that, under and because of pressure, carbonated cola is supercooled (at -3 degrees);

I would be quicker to point the finger at the various stuff disolved in the cola. Keep in mind, salty sea water freezes at like -4°C at normal pressure.

Also, if Urwumpe's claim that Cola freezes at -8°C is correct, then I wouldn't put the freezing down to depressurization. I very much doubt that the little bit of air trapped at the top of the pocket would cool another 5 degrees when expanding. The pressure isn't really that high, is it?

I think it might have something to do with the bubbles being a more pure water, then before. If the concentration of whatever is keeping Cola from freezing drops when the bubble is created, then the thin layer of water, at -3°C might freeze.

---------- Post added at 05:35 PM ---------- Previous post was at 05:27 PM ----------

Also, I don't know how careful Urwumpe was when bringing the Cola back inside, but supercool liquids will only stay liquid if there is no disturbence in the liquid. If you nudge the bottle a little bit, the super cooled state will disappear.

Unless Urwumpe was really careful when bringing the Cola inside, I would throw supercooling out of the window.

 

[cjp]

Why wouldn't distilled water boil in a microwave, and why would the fork make it boil?

Water boils when bubbles of water vapor appear spontaneously. These bubbles start very small, and for water to really boil, these bubbles need to grow.

At the boiling point (100 degrees C), bubbles are in equilibrium, and they neither grow nor shrink. Above that temperature, bubbles grow, and at lower temperatures they shrink. Boiling water is actually a little bit above boiling point, but it is really only a tiny difference, because the growing of bubbles (which turns water into vapor) costs heat, so it effectively stops water from becoming a lot warmer than 100 degrees.

But this story is only really true for large bubbles. For small microscopic bubbles, the rules are a bit different, and they tend to shrink faster. As a result, a bubble needs to have a certain critical size to grow. If it is smaller, it will shrink and disappear. For higher temperatures, this critical size is smaller.

The critical size is much larger than a single water molecule, and as a result, bubbles don't really start out of nothing. There needs to be something in the water that makes it easier to form a bubble. That 'something' can be a variety of things, but rough surfaces and dust particles are quite effective.

In the absence of such 'nucleation sites', bubbles don't form, and the water will continue to heat up. It's quite possible to make liquid water of 110 degrees Celsius in this way. When you have water of that temperature, and you add 'nucleation sites' afterwards (a fork, powder or something else), all that built-up energy will suddenly release, and all the bubbles that appear simultaneously can together cause a sort of an explosion.

See also superheating.