Questions on thermite.

[DDavisF22]

My chemistry teacher is helping me make thermite and he is the type that asks a lot of questions and gives out very few answers. so ive still got a lot of questions left before he will okay me to make thermite.

 

i read that thermite used in welding is 25% Al and 75% Fe2O3, is that true and should i use this ratio? i also came across this ratio: 2 mols of Al is equal to 1 mol of Fe. True?

 

know any good ways to make iron oxide (Fe2O3) quick? i found one that sugests taking steel wool and dipping it in vinigear and leaving it in a jar for roughly 15 minutes. good idea?

Edited January 14, 2009 by DDavisF22

[iNow]

If you're chemistry teacher is helping you, a student, to make thermite then he's a total moron who should be locked up. No, much more likely you're trying to make it yourself and are looking for a hazmat violation.

[DDavisF22]

Thanks for the help. my science teacher okayed it becasue once im done testing this i plan on entering it to a science fair for review.

 

anyways this is me double checking what ive learned, help would be nice.

Edited January 14, 2009 by DDavisF22

[iNow]

Hi DDavis,

 

Please just continue working with your teacher, then. I must be honest, it disturbs me deeply that you have such a shakey understanding of basic chemistry (at least, it certainly appears so by your two posts here), yet you're trying to make such a hazardous material on your own. Maybe your physics teacher has "okay'd" you to make a fission reaction, too... Doesn't mean you're not going to hurt yourself and others very very badly.

 

Just be careful, and try to use your head on this type of stuff. I don't mean to sound like a jerk, by my concern is genuine and I do distrust the authenticity of what you've told us here.

[hermanntrude]

inow has a point. Thermite is an extremely dangerous substance. I'm a chemistry instructor at a college and i'm too scared to try it yet. I've been thinking about doing it for a year now and still haven't convinced myself it's safe enough to do, even in the parking lot when it's empty.

[DrP]

Our chemistry teachers used to demonstrate the reaction behind a blast pannel. (With a sand bucket and fire extinguisher at hand). This was in the 80's.

[DDavisF22]

thanks for all the concern. you are right, my background in chemistry isnt very much. thats why im here. trying to learn more. ive done almost everything i can do on paper w/ thermite and i thought id try to get an outside opnion before my science teacher makes it.

[inuhbad]

Hermanntrude & INOW's concern is very well grounded in reality...

 

That said, DrP is right in that many teachers in the past have not always been so 'Reserved' in what they taught to their students! They were very truthful in their teachings to their students, and if a certain student showed great aptitude in Chemistry they would often pull them aside & tutor them further in more 'risque' areas of chemistry.

 

At least that was what happened to myself and two of my friends when we were in school in the early/mid 90's...

 

I was the president of an adolescent 'Model Rocketry Club' that we created, and the things we learned from our teacher will forever be remembered with fondness, and unrestrained appreciation.

 

In the 1980's and early 1990's, in the days before 'Zero Tolerance' (also known as ZERO THOUGHT) policies being adopted across America's public school system, the teachers were given infinitely more freedom in their lesson plans. Some took advantage of that freedom in order to draw students' attention by presenting more FUN, and EXCITING aspects of their courses at the beginning of the school year at time of registration.

 

I still to this day remember the day of registration, my Chemistry teacher was putting on a display to boost people's interest in chemistry (to get more people to sign up for his class), he had a few of his students from the previous year displaying a giant 2'x4' tubular balloon filled with Acetylene, and 'Gold Pennies' laid out on his registration sign-up table... They lit the balloon which quickly burned up in the gymnasium, and he laughed as every student that walked up to his sign-up table was hopping, skipping, and bouncing around while the floor made loud *POP*POP*POP* noises and little puffs of smoke!

 

Later when in his course he taught us how to produce Acetylene-filled balloons, Turn copper pennies & Nails into Brass (not 'Gold' as was the common misconception), and he showed us how to make the ever wonderful, popping, Ammonium Triiodide Crystals which he had strewn about on the floor in front of his table during the sign-up!

 

(The Janitor didn't think the purple stains on the floor were too cool though!)

 

Thermite, on the other hand is incredibly dangerous! And although there was a 'Zero Tolerance' policy prohibiting the instruction of 'Dangerous' things, we were also taught how to make it. We, ourselves, were not allowed to do so, but the instructor gave a demonstration of it, nonetheless. It was certainly impressive to see it burn through steel... IIRC, it was a small amount, probably ~50grams, but still cool. We all stood about 50' away as he lit a magnesium strip and we watched it burn with welding goggles (the little Acetylene gas welding goggles, not the full face shields which are much darker)...

 

Later the next year, the teacher had to change his lesson plans to a 'Tame' one because a student of his later tried to make some himself to burn a hole through the principal's car, and in his frustrations with getting it to light, he got closer, it lit, and fried nearly half his face off and he also lost an eye. Luckily the school didn't get sued.

 

I had already learned what I needed to since I had already finished my AP Chem course, and being one of the top-3 in class he also taught me many other, more 'dangerous' things which involve my model rocketry club, but that's a bit off-topic. Let's just say we stopped buying model rocket engines, and our rockets' performance went waaaaaaay up!

 

I'll have to agree with INow & Hermanntrude though. I'd avoid this, and if your teacher IS working on this in-class, continue to learn from him/her, but make sure you talk with your teacher after class. Stay after class to discuss things, or even after school. If your chemistry knowledge is a bit lacking, it is important that you learn these things, and learn them well.

 

There is nothing more dangerous in chemistry than only having a little bit of knowledge as that 'Little Bit' of knowledge is usually more than enough to get yourself into a WORLD OF HURT.

 

That little bit of knowledge can get people into a lot of trouble as they don't yet realize just how much they don't understand about chemistry. I know enough to humbly know that I don't know enough to do certain things I'd like to do so back to the books I go... I'll ask questions on here, but I suggest you ask your Chemistry Teacher to take some spare time after school or during a lunch or study hall period to tutor you more, and you'll be surprised at the things you may learn!

[DDavisF22]

haha, thats the problem. this is an all after class "assignment". and the more he teaches the more i notice how little i actually know.

[hermanntrude]

thanks for all the concern. you are right, my background in chemistry isnt very much. thats why im here. trying to learn more. ive done almost everything i can do on paper w/ thermite and i thought id try to get an outside opnion before my science teacher makes it.

 

your science teacher is going to make it now, eh? wasnt it originally going to be you?

 

All i'm saying is be extremely careful If you DO do this, then your science teacher must be a very experienced person and hopefully he/she will be the one setting the experiment up and overseeing the safety issues. If anything goes wrong due to any advice given on this forum, we cannot take any responsibility.

 

However, I salute your courage and wish you luck if you do this.

 

DrP, what kind of fire extinguisher did the instructors use? it'd have to be a damn good one... even the ones designed for metal fires are going to have a hard tim putting out thermite. basically once it's started it won't stop till it's finished. And to do it behind a demonstration screen indoors is downright irresponsible, in my opinion. if you're gonna do this it should be done outdoors.

[inuhbad]

Hermanntrude, you're totally right about the extinguishers...

 

The thing with Thermite is that, I seriously doubt that ANY extinguisher can put it out... DrP mentioned the use of a bucket of sand, but, in my opinion, that's not going to be enough. Once burning, there really is no way to put it out that I know of, you have to simply wait for the whole batch to burn itself out completely...

 

When I witnessed thermite back around 1995, the instructor did this outside by the metalworking (machining, foundary/casting, & welding) shops outside a good 30+ yards away from anything else. It was setup on top of a steel plate sitting on a large sand pile ~6' high and 40 feet in diameter. The welding shop uses the sand pile to allow some larger structural welds to properly cool slowly by burying the welds in sand and leaving them sit overnight. THus there was always a large sand pile back there pretty far from anything else (on the far end of the parking lot outside the shops).

 

Once the burning reaction was completed, and you had nothing but a large pile of red-hot burning metal/slag, and various burning sparks/bits of metal that showered around nearby, the teacher and two of us used shovels to shovel sand on top of all the burning red-hot particles/chunks. That took care of the 'little' burning bits carefully around the MAIN molten metal area.

 

Then we (from a distance) threw more & more sand on top of the molten chunk of slag that had melted clean thru the steel plate! We buried it in the sand, and the next day it had rained pretty good, so then 2 days after we lit the thermite, the teacher went back with a shovel, thick insulated welding gloves, & bucket of water. He dug up the larger chunks of molten metal, and just as a precaution, he put them all in the 5-gallon bucket of water (really filled only ~2-3 gallons). Surprisingly he said some of the chunks were still pretty warm!

 

I asked my teacher if I could take a chunk home, and although that was a number of years ago, I probably still have it somewhere in a cardboard box in my parents' garage back home.

 

There WAS a fire extinguisher nearby when I saw it lit, but that was mostly to hopefully stop any secondary fires from lighting up or spreading (if for some reason a molten bit of metal flew far enough to ignite the grass a good ~40 yards away. It wasn't likely to happen, but just incase.

[hermanntrude]

your instructor made a dangerous mistake. Putting chunks of metal into water can cause them to crack and explode, sending hot chunks of metal flying around. Any attempt to cool the sand and metal could cause either the chunks of metal or the glass made from the melted sand to explode.

 

This reaction is fraught with dangers

[DrP]

DrP, what kind of fire extinguisher did the instructors use? it'd have to be a damn good one... even the ones designed for metal fires are going to have a hard tim putting out thermite. basically once it's started it won't stop till it's finished. And to do it behind a demonstration screen indoors is downright irresponsible, in my opinion. if you're gonna do this it should be done outdoors.

 

OK - She had a large clear desk. A large 2 inch deep tray filled with sand (about 1.5m x 0.75m from memory). In the middle of the sand tray she had a large ceramic tile/plate. She had a small pile of the Al and Fe2O3 with a pinch of KMn04 on top with a Mg ribbon sticking out of the top as a fuse. There were blast shilds accross the front and angled to the sides of her demo. I don't know what extinguisher she had, but she always had one near her desk anyway.

 

The reaction, although very hot and unstoppable - didn't last that long due to the amounts of material she was using. I think it was safe the way she carried it out - although it was about 1986. She lit the fuse (wearing all her safety gear) and legged it back round to the front so she could watch it from behind the shielding with the rest of us.

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PS - this was the same teacher who let me try burning Mg ribbon in pure oxygen. That was a bit scarey - but quite cool. Was suppose to be purely a teacher demo - we got to burn it in air and the teacher then demonstrated it an oxygen gas jar (with one of those long metal spoons with a cymbol shapped guard round the handle which closes off the gas jar). I asked if I could have a go and she said "alright". I'm ashamed to say that I bottled it a bit and was a bit shakey, but won some cool points for doing it iin front of the class.

[jdurg]

your instructor made a dangerous mistake. Putting chunks of metal into water can cause them to crack and explode, sending hot chunks of metal flying around. Any attempt to cool the sand and metal could cause either the chunks of metal or the glass made from the melted sand to explode.

 

This reaction is fraught with dangers

 

Not really that dangerous. After two or three days in the sand with the rain that came down, the metal would not have any potential to explode. If he did this shortly after it had solidified, then yes, it would be quite dangerous.