I now have a habit
of being a bullshitter, because in the pub one day, to my work mates, I told them of the fact its very difficult to heat ice in a microwave.
Because the ice isnt liquid - the microwaves dont have any effect on the ice cube.

It ended up being a massive argument, because everyone thought i had just made it up.

I watched this one day on TV (one of the science satallite channels I think) but to this day, cant remember where I saw it, nor any links on the internet.

Did i dream this?

Can anyone back me up?
(Dan dan dan They tik urh jerbs!!!, Fri 14 Jan 2011, 10:20, 16 replies)

Yes I'll back you up - YouTube the video.
Something to do with microwaves working on fats in liquids as well, innit? But yes - there was a documentary/science bitz piece on it where they banged a bowl of ice in a microbe and zapped it for about a minute, I think, and fuck all happened - the only water in there was expected from the ice being out in somewhere room temperature.
( Je suis un vagabond is an unfunny, up your own arse middle class knob, Fri 14 Jan 2011, 10:28, closed)

Hmmm...
I'm guessing ice on it's own would take longer to melt in a microwave than ice in a little bit of water, but I'm not that technical...I know the defrost setting on a microwave never seems to work so you may well have something here...
( snee held his breath since, Fri 14 Jan 2011, 10:30, closed)

I'm off to microwave an ice cube.
Will let you know in a minute.
( monkeyboyalpha jumping on the bandwagon since, Fri 14 Jan 2011, 10:33, closed)

Well
the icecubes pretty much all melted in a minute, that's seems to be that theory fucked.
( monkeyboyalpha jumping on the bandwagon since, Fri 14 Jan 2011, 10:38, closed)

but was your huose warm?
we need to figure out what made the ice cubes melt.

You neglect to tell us your microwave is in a smelting plant.. etc
(Dan dan dan They tik urh jerbs!!!, Fri 14 Jan 2011, 10:49, closed)

alright,
two identical ice cubes out of freezer, one on a plate on the worktop, other on plate in microwave.
one minute later.
plate is full of warm water,
Unless I'm heating ice wrong, your theory is bollocks.
( Filthy narwhal titty titty tits tits tits, Fri 14 Jan 2011, 11:15, closed)

You want a technical answer?
Water molecules are bi-polar, meaning that they have a slight negative charge at one end and positive at the other. H2O is shaped like a boomerang, with the oxygen in the middle and the hydrogen making and angle of about 120 degrees, as I recall, so the two hydrogens (stripped of their electrons by the oxygen) have a positive charge while the oxygen, with its two extra electrons, has a negative charge. (By the way, this is why ice expands- the molecules start forming crystalline lattices in hexagonal arrays, which take up more space than when they're all just jumbled together. Kind of like fitting together K'nex results in something larger than a pile of parts.)

Microwave energy heats water by taking the water molecules and rotating them back and forth. Molecular motion is what we register as heat, as I'm sure you remember from childhood science classes, so yanking the water molecules back and forth makes whatever they're in heat up. (The microwaves similarly affect other polar molecules, of course, which is why sugars and fats also respond to them.) So yes, microwaved ice melts just fine.

The fun part is when you put something metallic in there. The microwaves induce electric currents in metals, resulting in the fireworks show we've all seen. But if you put in a ceramic mug of water that happens to have a fair bit of iron in it (red clay) or other metals (I think white clay has manganese in it, but can't remember for certain), you induce currents in the metals mixed into the ceramic. The huge electrical resistance results in the ceramic heating, and the microwaves are absorbed by the ceramic instead of whatever's inside it. The result: you burn the fuck out of your hand taking the mug out of the microwave, but the stuff inside is still cold.

Now, you want something freaky with ice? Mythbusters did an episode where they replicated a video showing a couple of guys igniting a bucket of thermite in top of ice blocks, resulting in a huge explosion. The result? A huge fucking explosion. Why? Beats the hell out of me.

Thus endeth the science lesson for now. And if you think the above was bullshit- well, Google is your friend. Go see for yourself.
( Wanderer, Fri 14 Jan 2011, 11:15, closed)

But what was the result?

(TheColonel, Fri 14 Jan 2011, 11:26, closed)

The thermite reaction produces molten iron...
... at just under the boiling point of aluminium (around 2,500'C).

If you put a bucket-load of shit-hot molten iron onto a block of ice the result is likely to be a massive burst of super-heated steam propelling bits of semi-molten iron at varyingly scalding temperatures in every direction.

Not hard to see why it might explode. Also quite easy to see why you might prefer to do this from a concrete bunker half a mile distant.
( Ugi , it's a game of give and cake, Fri 14 Jan 2011, 11:28, closed)

Mythbusters
www.youtube.com/watch?v=BnHR4cMXiyM Mythbusters at least didn't invent their own science to account for it like Brainiac did.
( 0nyx, Fri 14 Jan 2011, 11:47, closed)

"The result: you burn the fuck out of your hand taking the mug out of the microwave, but the stuff inside is still cold."
I was going to say I learnt this one the hard way, but the truth is that I didn't learn - I keep heating the same mugs in the microwave despite the horrible burn I got a couple of months ago.
(xanthine, Sat 15 Jan 2011, 4:50, closed)

Nearly right
But... water is not bi-polar, it is dipolar. Water molecules do not suffer from bouts of mania and depression.

Microwaves will only induce rotational transitions in liquid or gaseous water and so will only heat it in these states. At zero degrees water is at its triple point and exists as solid, liquid and gas. Unless the air temperature is below zero small amounts of the water present will be in its liquid form, absorb the microwaves and increase in temperature. This in turn will heat the bulk solid and cause it to melt.

At lower temperatures it *could* be possible to see this effect but you would have to control the conditions very carefully.
(el perro grande, Sun 16 Jan 2011, 23:37, closed)

I wrote that in the wee hours of the morning, in a bout of insomnia.
I couldn't come up with the term dipolar. I knew that bi-polar wasn't quite right, but went with it anyway.

So, any idea why a lit candle in a running microwave will produce ball lightning and make it look like Gozer has moved from the fridge to the microwave?
( Wanderer, Mon 17 Jan 2011, 1:12, closed)

Short answer...
no idea.

Ugi: I have to agree with your explanation and don't understand why the mythbusters guys say that it's not clear why it explodes etc. They do mention that the thermite reaction produces around 4000 C and I don't have a problem seeing why that would explode in contact with water!
(el perro grande, Mon 17 Jan 2011, 10:06, closed)

If you watch the link he gave
there's a vid of someone lighting thermite on a frozen lake, and there's no explosion. I notice that they're using a much smaller amount of thermite than they did on Mythbusters. Jamie speculated that the flash of steam may have aerosolized the thermite, so perhaps you need to burn a large enough quantity of it to have some unburned when it flashes?
( The Resident Loon Not a demographic. Do not measure., Mon 17 Jan 2011, 15:29, closed)

Yep
makes perfect sense to me.
(el perro grande, Wed 19 Jan 2011, 23:23, closed)