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Allassonic/Hot Chocolate Effect
SFOGuyNow I'm wondering if the powder has anything at all to do with it; or it's just the entrained air bubbles from the stirring being released and disappearing...although your statement about "equilibrium" seems to indicate the powder (until full dissolved) holds onto the air bubbles/supplies a surface for nucleation (I think I used that correctly).
So: would talcum powder work? hmmm
Works with most hot liquids with powders, I think I first noticed it in a mug of instant hot cider......
https://en.m.wikipedia.org/wiki/Hot_chocolate_effect
The hot chocolate effect, also known as the allassonic effect, is a phenomenon of wave mechanics first documented in 1982 by Frank Crawford, where the pitch heard from tapping a cup of hot liquid rises after the addition of a soluble powder. It was first observed in the making of hot chocolate or instant coffee, but also occurs in other situations such as adding salt to supersaturated hot water or cold beer. Recent research has found many more substances which create the effect, even in initially non-supersaturated liquids.
It can be observed by pouring hot milk into a mug, stirring in chocolate powder, and tapping the bottom of the mug with a spoon while the milk is still in motion. The pitch of the taps will increase progressively with no relation to the speed or force of tapping. Subsequent stirring of the same solution (without adding more chocolate powder) will gradually decrease the pitch again, followed by another increase. This process can be repeated a number of times, until equilibrium has been reached. Upon initial stirring, entrained gas bubbles reduce the speed of sound in the liquid, lowering the frequency. As the bubbles clear, sound travels faster in the liquid and the frequency increases
Self-Freezing Coke
kceaton1>> ^spoco2:
Cool. I was initially concerned that it'd have to have something nasty in it to do this, but what it seems is actually happening is that because the coke is stored under pressure, it can be kept below its normal freezing temperature without it actually freezing. Then when you open it and mix it around, you've released the pressure and it can now freeze.
The taking a swig is presumably just to make room for the expansion on freezing.
At lease this seems to be the explanation.
Along with this it may be a form of supercooling and when the bottle is open, nucleation (the bubbles formed by the CO2, for everyone that doesn't know what I'm saying) begins to allow ice crystals to form in the water that is already below freezing in the storage machine.
Exploding Superheated Water
Friesian says...Would this be something to do with the lack of a nucleation point? So because there are no impurites there's nothing for a bubble to form on, and thus there's less way for the water to expend the energy to the surroundings? Then when you drop a dirty penny in there's lots of places for the bubbles to form, and thus suddenly all the energy is unleashed at once - hence the kaboom effect. Is that what's happening here?
zero gravity water-bubble: waves and alka-seltzer experiment
Memorarenext mission: Mentos and Diet Coke.
Heterogeneous nucleation ftw.
Freeze a Beer in 2 Seconds
pho3n1xi hope i'm not wrong, otherwise i'll get run over by the sift bus, but i'm pretty sure the explanation is incorrect. i do this with my Smart Water daily at work, and as far as i know, there's no CO2 in my water, releasing pressure.
the real reason this happens is nucleation. though i don't get why the initial rise of CO2 when the bottle is opened does not provide that nucleation. with water, all that is required is a bubble, and the supercooled water will start to form ice crystals on that seed. in the beer's case, this was the sudden formation of CO2 bubbles at the bottom due to the violation of Man-Law (beer tapping). this formed a seed where nucleation occurs. leaving the bottle closed, and simply giving it a quick shake (as i do with my water) should provide the same results.
( http://en.wikipedia.org/wiki/Supercooling )
water example: http://www.youtube.com/watch?v=YuPfsAdEG2E
supercooled water - instant ice
messengerWiki says: If cooled at a rate of the order of 1 million kelvins per second, the crystal nucleation can be avoided and water becomes a glass.
Now there's a vid I want to see.
Myth Busters: The Diet Coke & Mentos Fountain Secrets!!!
bamdrewhmm... they didn't go into how the caffeine and aspartame could be aiding in the nucleation... thats the only thing I wanted to know...
Diet Coke+Mentos=Human experiment: Do you think his reaction is faked?
joedirtThe idea is that he explodes and they threw blood on the wall. and then he is laying on the ground.
I voted down because he chewed up the mentos. The idea behind mentos is the increased surface area allows more bubbles. I think MythBusters credits nucleation sites. So by chewing the things, he just got a mouthful of foamy diet coke.
I'm half convinced all the internet vids are put there by Coca-Cola. Do you have any idea how many 2-liters have been wasted in the last month. I should buy coke stock.