Microscale Thermite Reaction

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Harvard Natural Sciences Lecture Demonstrations

Күн бұрын

Пікірлер: 40

@A3Kr0n 8 ай бұрын

I bought two large bearings at a farm rummage sale so I could do this. It took years to rust one bearing. I gave up and threw it into the wood stove. I took it out in the Spring with a good coat of rust forming. Sparks good!

@SusanSchmidt-fr9ym 3 күн бұрын

Quick rusting trick: put the iron bearings in salt water for several days, then take out, put them on a tray that you don't care about, and let them air dry. Don't wipe off any of the salt water before you let them dry.

@russellpurdie 8 ай бұрын

That's why in Australian coalmines they don't use alluminium underground in general.

@bataalexander9703 8 ай бұрын

I would have never come up with this idea, although it is so obvious watching from backwards, of course. Thank you!

@scambroselauntrellus3681 8 ай бұрын

"Where should we do the microscale thermite video?" "Let's do it in the gray experiment chamber" "Cool, should I wear gray?" "No, blue."

@Muonium1 8 ай бұрын

This is interesting, but is the mechanism truly the Fe2O3 + Al --> Fe + Al2O3 thermite reaction? I'm skeptical. If one takes two polished steel spheres, even smaller than those seen here in fact, and puts a plain piece of paper between them, then smacks the spheres together at even modest velocity, the paper literally pyrolyzes and explodes due simply to the conversion of kinetic energy into heat at the very small collision point. It's a type of energy focusing phenomenon similar but less dramatic to the kinds that Seth Putterman's lab explores at UCLA. So is there really a metathesis reaction going on here, or is the aluminum simply being heated, melted, and burning in air? If there are no small Fe particles left over on the ground, I suspect the latter. Have you checked with a magnet?

@Engineer_Stepanov 8 ай бұрын

Can be use spectrometer for light analyse.

@NatSciDemos 8 ай бұрын

Paper and aluminum foil are very different materials: paper is a carbon-based material that ignites at about 230 C, whereas aluminum foil available from the supermarket is an alloy (usually with iron and silicon) that has a melting temperature of 660 C at minimum. As @Engineer_Stepanov points out, one could analyze the emission spectrum of the sparks to see if it matches up with aluminum oxide. Another test one could do is to smash two aluminum spheres together to see if the same thing occurs as with rusty iron and aluminum foil.

@adrielburned6924 8 ай бұрын

@@NatSciDemosthere is a vid by Action Labs I think, he uses paper and then tin foil. The foil is "exploded" away with a micro shockwave ripple around the hole. I'm not making any claims either way, but just letting you know it works on foil too.

@camojoe83 7 ай бұрын

Hey, there's the magnet idea. Knew someone would pop in with it.

@ice_aspect5847 7 ай бұрын

My best guess here is the same mechanism here is used to ignite the reaction. And that's why this one makes sparks and paper doesn't.

@r0cketplumber 8 ай бұрын

How many students have smashed digits with a poorly-aimed blow? As for determining if it is actually a thermite reaction, I'd try using a couple lumps of a different oxidized metal, perhaps copper for a nice bright green flash, but the copper may not be hard enough to cause a reaction on impact at reasonable speeds.

@YunxiaoChu 8 ай бұрын

You could always electroplate

@bl0ccr4fter24 7 ай бұрын

I’m itching so bad to joke about them slapping balls together, but I’m going to resist it as best I can.

@sakelaine2953 7 ай бұрын

Rock banging based technology is the best

@mace8873 4 ай бұрын

If you don't inspire your students to be curious, and _wanting_ to learn more, you should resign as a teacher, I think you should view their unsupervised experiment as a badge of honor, well done!

@WXUZT 8 ай бұрын

Remarkable ! Thank you for your time.

@ariannasv22 7 ай бұрын

"More imaginative" thats a polite way of putting it lmao

@melissahamilton855 7 күн бұрын

Ideas of how to turn this demonstration into a jr. high science fair project? What variables should be changed?

@SusanSchmidt-fr9ym 3 күн бұрын

Hmmm... the first one that came to mind is to just drop one ball on top of the other from different heights and see how high you have to drop the ball from to get a spark. Would have to learn some physics to relate height to velocity of the ball when it strikes the other. However, it's a glancing blow that is used when the balls are struck, so I wonder if a pendulum holding one ball would be better, and letting it swing from different heights. I've never done either of these, so it'll be interesting to know if it works. Another idea suggested by a colleague is to try painting layers of iron oxide paint and aluminum paint on some substrate and seeing if you could set it off with an iron ball. Test the number of layers, different substrates, different geometries. If you have access to a fume hood and the supervision of a chemistry teacher, you could try setting it off with Mg ribbon. Hope that helps!

@memejeff 7 ай бұрын

Very cool idea. Really neat.

@ozlemelih 8 ай бұрын

She has balls

@ralanham76 8 ай бұрын

🎶 and knows how to 🎶 use them

@wisdomoftheshadows 7 ай бұрын

I remember chinese fireworks like this. They called them dragon balls. Hit them together theyd spark.

@camojoe83 7 ай бұрын

Yeah but they were covered in Armstrong mixture if I remember correctly.. at least it was easy to recreate them with Armstrong's and lacquer... I remember those from my childhood. They'd get worn out real good after a while and it would never fail that I'd pinch the hell out of a finger or something trying to slam the last pops out of em.

@wisdomoftheshadows 7 ай бұрын

@@camojoe83 They smelled nice.

@cHAOs9 7 ай бұрын

I dont know if that's actually a thermite reaction. I think it's not. Steel balls hitting each other will heat and compress the air between them, creating a shockwave. It works with clean balls and paper too. In this case, it very well may be simply burning the molten base aluminum in the oxygen in the air, and blowing off a tiny bit of iron oxide. Considering the velocities of air, i would be very surprised if the two had a chance to react with each other. Frankly, it would look about the same since either way oxygen is bonding to molten aluminum. In fact, the air oxygen would be MORE energetic since it doesn't have to rip off of an iron. Prove me wrong. I'd love it if this was actually a thermite reaction. Blowing up thermite doesn't usually make the thermite react.

@camojoe83 7 ай бұрын

Recreate this experiment over some clean butchers paper, then sweep the paper with a magnet when done. If you even get one microsphere of iron from it, then it thermited (it's a verb now, sorry)

@cHAOs9 7 ай бұрын

@@camojoe83 True. With possible exception of Fe3O4 magnetic oxide that could result from heated Fe2O3. But that should be easy to see the difference. Good idea.

@camojoe83 7 ай бұрын

@@cHAOs9 the other thing that might be happening here is an oxide detonation. If you watch Taofledermaus shoot those big aluminum blocks he has, there's almost always a good flash on the impact. Doesn't seem to matter what the slug is made of, either. So maybe the rust, the impact, and the foil being slightly oxidized (not sure that's possible? Maybe only on one side?) just makes a little blasting cap when you slam it all together.