Hi there! Got this in an email a little while ago, and can’t find anything on Snopes. It’s about boiling water in a microwave. Can anyone confirm or deny the truth of this? Thanks!
“The quickest way to a man’s heart is through his ribcage.” --anonymous redhead
Cristi,
This passed through here within the last two weeks; I think the thread is in GQ.
Anyway, in a smooth vessel that does not offer any nucleation sites (which would be irregularities) on its surface, water can become superheated and commence boiling when something, such as a spoon, powdered beverage mix or some such is introduced. The story in the email is a little overblown.
Sounds loke this thing was started by a tea kettle manufacturer.
I’ve boiled water in the microvave a gazillion time and I’m still alive. (sort of).
Oh, phooey! 
Water can’t be “superheated” in the environment of a microwave oven! That’s why Wally is still perkin’!
This “buildup of energy” crap makes me tired. Water is no better a repository of energy than any other substance. Water, being prone as it is to boiling and so on at easily produced temperatures is less an example of being “energy-retentive” than many other substances.
Boiling temperatures (the points on a temperature scale where given liquids become gases) can be modified, but only through the manipulation of pressure. Since your average microwave oven is quite well-ventilated (ever wonder why you can SMELL what you’re nuking?), no diddling with pressure is taking place.
Maybe there should be a “DUL” website? One for “DUMB urban legends?”
I don’t know why fortune smiles on some and lets the rest go free…
T
Yes, it can. And it is a not rare occurence. I, as have many, have witnessed the superheating/nucleation-boiling phenomenon. It’s really not that unusual, but, as I said, the email is overblown. I’m not sure what environmental variables the posited idiot starring in the email could have manipulated such that this event gave him a poached face, but the superheating phenomenon occurs often.
Someone 'splain to me how water can be ‘superheated’…that is, heated beyond its boiling temperature, without increasing pressure.
Water can’t get above 212 (100 for you centi-freaks) at standard pressure. And, at that temperature, a splash of one cup of water would give a scald, but certainly not second-degree burns, unless the kid’s reflexes operate on a five-minute delay.
Fake letter, says I.
http://www.straightdope.com/ubb/Forum3/HTML/003452.html
Don’t understand the physics myself, but this should help out.
The upshot is, boiling requires sites for gas bubbles to form. Boiling something on a stove usually involves an old metallic vessel with plenty of pores, oxidation, scratches, etc. which thus become nucleation sites.
Microwavers often use more “perfect” vessels - glass and ceramic containers which lack the sorts of crud which provide 100 degree C water molecules the opportunity to band together and form gaseous escape committees which make a run for the surface. Sure, water can evaporate from this kind of vessel, but it won’t boil off, since there is no place to start the committees. Okay, so I’m drawing out the metaphor a bit much.
So when you pull out your brand new smooth ceramic mug full of 102 degree C water out of the microw, a little bit of lint drops off you forehead into it, and poof, lots of nucleation. Probably a very rare occurence since who really keeps lint on their foreheads?
Any similarity in the above text to an English word or phrase is purely coincidental.
I used to rock and roll all night and party every day. Then it was every other day. Now I’m lucky if I can find a half an hour a week in which to get funky.
Oh TBone2, you’re so wrong.
and Oh, Beatle You’re so right. Dig:
Water can be superheated, especially in microwaves.
A portion of the water in the cup is becoming superheated, i.e.the liquid temperature is actually slightly above the boiling point, where it would normally form a gas. In this case, the boiling is hindered by a lack of nucleation sites needed to form the bubbles. This never occurs when boiling a kettle, for example, because the presence of the rough surface of the element, as well as the convective stirring from rising hot water, are sufficient to produce proper boiling. Turbulence in liquids is known to provide enhanced nucleation in other cases: when you pour a cola drink, for example. In some cases, the addition of a tea bag (and, in the other case, simple movement–such as taking a cup o’ soup out of the microwave) suffices to allow bubble formation. Even with a large proportion of the water superheated, only a little will convert to steam, as the amount of latent heat required for this phase change is very large. I imagine that by keeping the cup still and microwaving for a long time, one could blow the entire contents of the cup into the interior of the microwave as soon as you introduced any nucleation sites. It is this sometimes explosive rate of steam production that means you should take great care when using a microwave oven.
And that’s the Straight Dope. Noonch.
“And on the eighth day, God Created beer
to prevent the Irish from taking over
the Earth.”
~SNOOGANS~
SmickD
what does “noonch” mean?
I don’t think that would happen… The way a microwave works so I’m told is that it heats up the water molecules in the food. That why yer food is always soggy if you use the microwave.
ants spend 20% of their day working…
The Neo-Comintern
Wow. Thanks guys! This was one of those “might be credible but I’m not sure so I’ll ask” deals. Thanks for the Snopes link, Alphagene. Don’t know why I couldn’t find it yesterday!
“The quickest way to a man’s heart is through his ribcage.” --anonymous redhead
I did a test the other night. Ran water in a cup for two minutes, then poured sugar in. Yep, it bubbled. Didn’t blow up in my face and scald me for life.
Hope that confuses the matter.