Question for the physics guys

Bozo Erectus

Bozo Erectus

Master Baker
Joined
Jan 22, 2003
Messages
22,389
When you boil water in the microwave, and then throw in teaspoon of sugar, it boils over like a volcano and spills all over the place. However, if instead of throwing a whole teaspoon, you drop in just a few sugar crystals, it fizzles a little, and then you can go ahead and safely add a whole teaspoon.

My question is: Where did all that energy (that would have erupted out of the water if you put a whole teaspoon) go? And why is the energy contained in the water untill sugar makes it escape?

edit: Damn! I should have called the thread 'My cup runneth over' :sad:
 
This is more a chemistry question imo.

Molecules of hot water are vibrating quicker than usual. Molecules of sugar disperse among them and replace molecules of gasses (such as oxygen) which were previously dissolved in the water.

Because of the extra vibrating, all molecules find somewhere to disolve very quickly and that releases many gasses in a short space of time.

Edit: I think ;)
 
Like for rain and other condensation, you need impurities for the boiling water to create the air bubbles that make it boil over rather than just steam away.
 
When you heat water in amicrowave, it creates a strange phenomenon called "superheating". It means that the water is at over 100 degrees, but has not evaporated. It is in a very fragile state-obviously it wants to evaporate. When you drop in a bunch of sugar, you mess up that fragile state, and the water spontaneously evaporates, throwing boiling hot water vapour all over the place, and then usually condesses, throwing hot water all over the place.
 
IglooDude said:
Like for rain and other condensation, you need impurities for the boiling water to create the air bubbles that make it boil over rather than just steam away.
Click to expand...

I duel good is onto something here. The impurities (sugar crystals) will help release (not create) gases from the water.
 
thetrooper said:
I duel good is onto something here. The impurities (sugar crystals) will help release (not create) gases from the water.
Click to expand...
That is what I said :crazyeye:
 
CoolioVonHoolio said:
oooo im going to try this!
Click to expand...

That is a very, very bad idea, seeing as spontaneous evaporation means boiling hot water goes everywhere, and sears skin off.
 
Try this: bottle of diet coke, penetrate the cork with a needle and place the bottle in ultrasonic water bath. :evil: Bring a mop too :D
 
nonconformist said:
That is a very, very bad idea, seeing as spontaneous evaporation means boiling hot water goes everywhere, and sears skin off.
Click to expand...
well too late now... it didnt burn me i was wearing stove gloves and was an arms lenth away...
another cool thing is get a can of pop empty it, and put a little bit of water in it. then put it over a stove until the water boils, right after it starts to boil pretty good take it and drop it in cold water (have the cold water ready)
the can will implode!
 
This is the basis of how bubble chambers work.The liquid used is liquid hydrogen.
The bubbles forming the track form on ion trails produced by high energy particles.

The original idea came to Glazer watching bubbles form in his beer in a pub ;)
 
Igloodude and thetrooper are right, I think, that the sugar provides nucleation sites for the formation of vapor bubbles in superheated water. So that explains the put-the-sugar-all-at-once experience.

What about the little-at-a-time experience, though? I can think of two reasons. One, adding sugar drives the boiling point up (but only by a little). Two, you give time for heat transfer to take place. Not so much the cooling off of the whole body of water, I suspect. More that the hot spots and cold spots get some time to even out. Microwave ovens are great devices if you like your food to simultaneously burn you and freeze you at different regions in a single large bite. ;) Waiting a minute does wonders to even out the temperature.
 
Sparta said:
Yeah, but you didn't include a clever anagram in your response!
Click to expand...

Her pet root certainly gets cool points for that. :goodjob:


Edit: Nucleation, that's the word I was searching for, thanks, Ayatollah So.
 
thetrooper said:
For stormbind?

This should be adequate: trim bonds.
Click to expand...
Whoosh! There was this big shadow and something flew over my head :confused:

I am utterly clueless. Does it refer to trimming hydrogen bonds?
 
For something to nucleate, doesn't it need to be supersaturated? :confused:

Maybe the small region is supersaturated but I would have thought the dissolved compounds were just replaced without supersaturation being observed.
 
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