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Totally Blowing Shit Up Tuesdays: Ice, Ice Baby

September 15, 2009

What's going on, everybody? Yeah, it's been a couple of weeks since our last installment of this lovely little series, but, you know, sometimes you need to take a moment from the explosive excitement and gather your thoughts. Hell, even Shakespeare took a little time after writing A Midsummer Night's Dream (I assume). That's right, I just likened myself to the Bard. Except, I have more hair. What? The Bard loved him a good explosion, as well, which is why his Globe theater burnt to the ground in 1613 after a cannon misfired during a performance of Henry VIII.

Did you see what I just did there? I combined several of my favorite things: Shakespeare, useless history lessons, explosions and Latin. Self-induced priapism is three, two, one...

Alright, let's get back on track. Originally, I saw this little piece of awesome on Brainiac, but since they've done the old bait and switch on explosions before, the "experiment" was repeated on Mythbusters. Satisfyingly, that smug grin was wiped off Adam and Jamie's faces (along with their so-called explosives expert) when they successfully caused a detonation by repeating the conditions previously reported.

The recipe for this explosion is easy: thermite + ice = explosion. Being that I'm not an expert, I'll let someone else tell you how to make thermite. Ice, I think, you can pretty much figure out where to get: water + cold = ice. Anyway, when you let the thermite reaction pour down onto a carefully constructed pile of ice blocks, it blows up. Don't believe me? Watch.



Now, why does this seemingly innocuous mixture of fire and ice result in explosive goodliness? Fuck if I know. Ask someone else in the field, and they'll give you some hand-waving explanation. My initial thoughts were that the ice sublimates under the extreme heat of the thermite reaction (up to 4500 degrees Fahrenheit), and such a rapid expansion of gas against a relatively solid wall of ice causes it to explode.

Another explanation is that the thermite induces the water which forms the ice to break down into its elemental units of oxygen and hydrogen. We've already seen the explosive nature of hydrogen a couple of times on here, and the mixture of the right amounts of hydrogen and oxygen form a really good explosion. My only problem with this is that hydrogen is very flammable. A curtain of molten metals burning down through a cloud of hydrogen should cause it to ignite fairly quickly. It doesn't seem like there would be an accumulation of sufficient amounts of hydrogen gas to cause an explosion like that.

Finally, a third explanation is that with the rapid sublimation of the ice into water vapor, it helps to aerosolize the thermite as it rains fire down through the ice blocks. Again, we've seen what happens when you mix fine powders and source of ignition. No one has definitively proved how this happens. In fact, I'm pretty sure that everyone who sets out to prove the mechanism of explosion ends up laughing and saying "What happens if we add more ice?"

The whole point of this is that, while the Brainiacs have been known to enhance their explosions, this is not one of those times. It's been repeated on Mythbusters with most satisfying results, AND it's been repeated several times by amateur scientists with video cameras and too much time on their hands. Not to mention a healthy love of explosions.

Now, if only other songs of ice and fire could finish so satisfyingly, I'd be happy. Or, better yet, maybe they could just, you know, finish.

16 comments:

Moooooog35 said...

I had Mexican* last night and did my own little explosion experiment this morning.

*Thermite not included.

Chemgeek said...

Thanks for the linky goodness.

I now plan on repeating this demo for my gen chem class. I'll probably have to wait until next semester though. I'll try to get video.

Cora said...

Awww, Mjenks, you brought TBSUT back. Thank you. Every TBSUT the five year old I take care of comes running for the 'puter to watch things go boom. This did not disappoint. :-)

~E said...

ooh! I loved that episode!

Soda and Candy said...

Explosiones!!!

Awesome. A triumphant return for the series.

Happy Hour...Somewhere said...

Thermite and Ice...you may have invented a new drink. I wonder what you would put in it?

Scope said...

I wonder what the reaction would be with dry ice?

My thought when seeing it originally, was that it was effectively a steam explosion / thermal shock sort of deal.

Eric said...

You know, James Taylor has seen fire and rain, but not sure about the ice.

Excellent post, If only there was a whole ice covered continent on which to give this a go.

BeckEye said...

I hope chemists do it periodically, and not while they're on their periods.

As for Mythbusters, again I say, "We need more Tory."

Raine said...

Mad cool!

Nej said...

THAT. WAS. AWESOME.

Jill Pilgrim said...

"My initial thoughts were that the ice sublimates under the extreme heat of the thermite reaction (up to 4500 degrees Fahrenheit), and such a rapid expansion of gas against a relatively solid wall of ice causes it to explode."

I love it when you talk chemistry.

Lisa-tastrophies said...

I love Tuesdays!! Worth every "bang" for my internet buck :-)

Lostinspace said...

I wonder if Homeland Security has you on their watch list.

Chaka said...

Mmmm......Thermite! It's good to see more explosions.

Cool as Folk said...

Whoa, whoa, whoa, I'm stuck on something you said. Water + cold = ice?

I just recently learned that if you throw a lighter from a high place, it will explode when it comes into contact with the ground. This I desperately want to try out.