Have you ever had an explosion in your microwave?

[Monique]

Did any experience that before? I was in the lab, luckily, microwaving 100 ml of water in an *open, no lid* 500 ml erlenmeyer flask. All of a sudden there was this big *boom* in the microwave like an explosion, when I open it.. water is dripping from the sides and about 25 ml were missing I was like: wtf

I actually experienced boiling delay with microwaves before, but not quite this spectacular - or dangerous -

 

[LURCH]

That kind of thing can result if you sue very clean water in a very clean container with very smooth sides. There are not sufficient points of veriation on which gass bubbles can form. So the water passes the boiling point by quite a bit before it can actually start to boil. Once a single bubble forms and creates a disturbance, the rest can flash transition to a gasseous state, expanding violently.

For this reason, many microwave ovens come with a warning not to boit water ni them. People have been injured by water that passed the boiling point but did not boil. A victim will continue heating the water, observing that is not yet boiling. Then, in an attempt to check the temp, they will remove the cup from the oven and look directly into it. The movement sets off the the transition process, and the cup acts like a guyser, spraying superheated water into the face.

It's been mentioned in the Forums before, but I thought it worth repeating to anyone who didn't catch it the other times. Important safety tip!

 

[Evo]

Thanks Lurch!

 

[kat]

Originally posted by LURCH


It's been mentioned in the Forums before, but I thought it worth repeating to anyone who didn't catch it the other times. Important safety tip!

Ouch, really...thanks for the warning!

 

[DarkAnt]

great...now I fear my microwave.

 

[cookiemonster]

Think I'll stick with the toaster from now on.

cookiemonster

 

[LURCH]

Originally posted by cookiemonster
Think I'll stick with the toaster from now on.

cookiemonster

Dude, DO NOT attempt to boil water in your toaster! Don't ask how I know, but it's a bad scene and you don't want to go there.

 

[motai]

Wouldn't it just be safer to take some wood, go outside, and build a fire? Or you could resort to a bunsen burner to do your cooking hehe.

 

[cookiemonster]

Originally posted by LURCH
Dude, DO NOT attempt to boil water in your toaster! Don't ask how I know, but it's a bad scene and you don't want to go there.

Good point.

But you know I have to ask... How do you know?

Edit: Ooh, looky me. I get a title. Don't I feel special.

cookiemonster

 

[Monique]

Originally posted by LURCH
For this reason, many microwave ovens come with a warning not to boil water in them.

Yes, or know how long to microwave it.

In the lab we always use the microwave to make agarose gels. Even though we add a powder that turns into a gel when heated, you still get a boiling delay. But since the liquid is very viscous, it doesn't really overboil. At this event I wanted to clean the flask, since some of the gel had cooled in it.

The microwave is very clean now

 

[ShawnD]

I've never had an explosion in my microwave but I have made huge fireballs in it . Put some rubbing alcohol in the microwave and nuke it for 15 seconds. Open the door use your light to ignite the vapours (wear leather gloves and a jacket).
It's lots of fun.

 

[Monique]

A classical example of: *don't try that at home*

 

[ShawnD]

If it makes you feel any better, I was doing it outside.
Microwaves are awesome.

 

[recon]

I've never actually microwaved water before, but I HAVE seen a video clip of it online. Just a small disturbance of the water would set the water boiling madly. I think there is a term for this called superboiling/superheating (can't remember which).

Anyway, why use the microwave? There's always the good-old kettle...

 

[rathma]

MythBusters?

Monique,

Have you ever seen the show "MythBusters" on the Discovery Channel? It's a great show about disproving common misconceptions about everything; like on this one episode tha I watched they were trying to discover any truth to the idea that if you drop a penny from the Empire State Building and it hits someone on the head, their head will explode and they'll die. They found out how tall the Empire State was exactly and crafted this tube to drop a penny down. They have this dummy that is exactly like a human in every physical way, and so they put one end of the tube on the dummy's head and dropped the penny into the other end, and, well... Let's just say that that particular "myth" is very much true. Yuck. Anyway, they often treat themselves to the pleasure of watching things melt, explode, and other such enjoyable things in one of their several reinforced microwaves. Your story reminded me of this as soon as I read it. You should try to see the show sometime. The hosts are complete psychopaths, but they're geniuses as well. Good show!

 

[Loren Booda]

Explosion in microwave

I didn't know what to expect from this thread - the epoch of decoupling or a bursting potato?

 

[Evo]

and don't microwave whole eggs still in their shell

 

[Dissident Dan]

Does it have to be in a microwave for this to happen? I didn't see anything in Lurch's explanation that seemed specific to microwaves.

 

[eagleone]

Originally posted by Dissident Dan
Does it have to be in a microwave for this to happen? I didn't see anything in Lurch's explanation that seemed specific to microwaves.

I think it has to be in microwave.
Microwave gives you uniform heating and temperature increase of complete water volume. If you use, for example, kettle and stove, you’ll have temperature gradient with hotter bottom and colder top – creating currents inside the kettle (no effect).
+ There’s question about pressure inside microwave oven (is it hermetically closed?).[/color]

 

[motai]

Originally posted by Evo
and don't microwave whole eggs still in their shell

Good idea, and also don't put in aluminum foil unless you want to see pretty blue flashes of radiant energy.

 

[Loren Booda]

How much do a microwave oven's peaks and troughs of energy vary, and over what distance? While defrosting meat in a microwave, I try to move it around asymmetrically to avoid on average what might be a "cold" zone. Even a rotating platter tends to provide an thermally unbalanced center.

-A hopeless physicist

 

[Monique]

Inteference takes place in a microwave, so there ARE 'hot and cold' spots. The microwave I used had a rotating disk, it wasn't until the time was up and the disk stopped turning that the thing unleashed :P

 

[Peter Pan]

"Super Heating" only happens with distilled water. The imperfections with tap water allow the water to boil at normal temps. You only need to be cautious when boiling distilled water.

 

[Monique]

When did you get that memo? I've never stuck a thermometer in a cup of water while microwaving it (can't be good :P), but superheating definitely occurs with ordinary water. How else would you explain the phenomenon of delayed boiling?

 

[jimmy p]

i thought microwaves only penetrated the first couple of milimetres of substances...how does that make them bery good at cooking?

 

[Loren Booda]

The microwave wavelength, .3 to 30 cm, may denote their typical penetration in a nonconductor. Heating occurs mainly by excitation of water molecules within the object.

 

[LURCH]

Originally posted by Dissident Dan
Does it have to be in a microwave for this to happen? I didn't see anything in Lurch's explanation that seemed specific to microwaves.

It is only likely to happen in a microwave, because it is heating the water rapidly that allows it to get well above the boiling point before something happens to set it boiling. Another heating method with similar speed would probably do it.

 

[Monique]

Actually, boiling water in a microwave takes slightly longer than on a stove. The thing is that there is no convection (am I saying that right?) in the water when you are microwaving it, on the stove there ís (warm water rises from the bottom, while cold water sinks down).

 

[timejim]

Originally posted by Monique
Did any experience that before? I was in the lab, luckily, microwaving 100 ml of water in an *open, no lid* 500 ml erlenmeyer flask. All of a sudden there was this big *boom* in the microwave like an explosion, when I open it.. water is dripping from the sides and about 25 ml were missing I was like: wtf

I actually experienced boiling delay with microwaves before, but not quite this spectacular - or dangerous -

Once I made the mistake of putting a cup of water in the mw using a cup that had a small, gold plated rim at the top. No explosion but immediately got a spectacular "lightning" storm inside. It scared me.

 

[Monique]

And everyone must already have tried to microwave an egg, I imagine :P