Talk:Thermite

Stating the temperature of a thermite reaction is scientifically incorrect

Technically a reaction releases energy, which in turn can be used to change the state of the reactants. To say that a reaction has a certain "temperature" is misleading: the actual temperature depends on the ambient temperature, rate of heat loss, etc. Nonetheless, it is nice to put in some numbers for average conditions so Mr.Layperson gets a feel for how powerful this reaction is without doing any math.

dictionary.com claims that it is thermit (without final e)

I spell checked the article of aluminium and the word thermite was non existing. To find out whether it was correctly spelled I looked it up at http://www.dictionary.com . This is the info dictionary.com gives:

"Thermit

A trademark used for a welding and incendiary mixture of fine aluminum powder with a metallic oxide, usually iron, that when ignited yields an intense heat."

So nothing about thermit as a name for certain chemical reactions, just that a brand name of such an chemical mixture is "thermit", without final e. Is dictionary.com wrong or Wikipedia? Or is the brand name "thermit" and the name of the chemical reactions "thermite"? If you'd find out that dictionary.com is wrong please leave a note saying so on this talk page. Tx in advance for looking this up. --Paulus/laudaka (add me to your YIM/AIM/ICQ/M$N M contact list if you like!) Laudaka's talk page 21:30, 12 May 2004 (UTC)

Merriam-Webster Online lists a substance called 'thermite' and a trademark called 'Thermit'. Issue resolved? --Smack 21:07, 20 Aug 2004 (UTC)

Thermite/Thermit discussion

"Or is the brand name "thermit" and the name of the chemical reactions "thermite""

Yes, the brand name is 'thermit' and the reaction is a 'thermite' reaction. --Anon.

Other Thermites

Is this a forum sorta thing? i am not sure... someone correct me please... well my question is could one make a thermit mix from aluminium and some other oxide...like howabout copper oxychloride?

Yes, a thermite reaction is simply a reaction involving a reactive metal and the oxide of a less reactive metal. Basically you can use any reactive metal, and any less reactive metal compound containing oxygen. Aluminum and rust are simply the most used, since they are more readily available.

And as I understand it, they release quite a bit of energy. I hear that copper/aluminum thermites are used in armor-piercing missiles though, so perhaps they have a greater ionization energy (is that the right phrase?). --Maru (talk) Contribs 23:15, 26 October 2005 (UTC)

Yes, cupric oxide/aluminum thermites typically attain a temperature that is above the boiling point of copper, which results in a gaseous product and an explosion. For this reason, such thermites with low boiling point metals involved are used less. Other mixes that will explode include ones that use zinc as the reducing agent or lead oxide (Pb₃O₄ or PbO) as the oxidizer. These mixtures also have high enthalpies of reaction.

Thermite Process (Ames Process)

So is the thermite process just the function of using thermite? Or, as I think, something different (but involving aluminium...)? This is not clear from the article, but the redirect from Thermite process is indicative that it might be. -- ~ender 2005-03-14 02:34:MST

Making Thermite

Should there be a section included on making thermite? I've performed small reactions myself, and they've always been very exciting to do. If the correct measures are taken, it's a very safe procedure because the material won't explode under normal conditions and it is nearly impossible to accidently ignite it. Further more, powdered iron oxide and aluminum are easily and legally obtained from online retailers like ebay. --Daveswagon 00:36, 17 Jun 2005 (UTC)

The article already mentions the weight percentages for mixing thermite from powders, but that information could be moved to a ==Production== section or something like that. As far as making the raw ingredients yourself (with household items), I tried and failed, but it may be possible. I would tend to leave out any instructions about getting rust from nails/rulers/etc unless someone has first hand experience and it does in fact work. --SCEhardt 04:11, 17 Jun 2005 (UTC)

I'd just like to point out thermite does indeed have quite a few dangers. True, there is basically no chance at all of it igniting unintentionally, but when it does ignite it is a powerful energetic material that can easily harm the unwary. A few particular points:

1. Explosions are in fact possible. The two main ways these can occur are due to pockets of moisture in either the ingredients, the crucible or anything the melt spills onto; or contamination of the ingredients with relatively volatile metals (e.g. zinc or zinc oxides). In the first case you get a steam explosion, in the second case the thermite reaction reduces the metal oxide but the metal is produced as a gas rather than a liquid. Either way, you get gobs of molten iron being thrown violently out. To avoid this, you need to be sure your ingredients are scrupulously dry, and at least moderately pure (a problem if you are making it from scrap metal). If it is going to spill onto the ground, make sure the ground is also very dry.
2. Even with some care taken to avoid volatiles, it is not uncommon for "spattering" to occur, small amounts of molten iron being thrown by traces of volatile contaminants. (In foundry and welding operations, much more severe, but still nonexplosive, spatter is also caused by overheated apparatus collapsing or dropping weights into the melt.) Consequently all flammable materials should be removed for a radius of several metres, and spectators should watch either from a safe distance or through a lucite screen.
3. Speaking of spectators, the high temperatures involved can produce quite a bit of UV light. To avoid retinal damage observers should either be placed so that they cannot directly view the core of the reaction, or else should wear welding goggles. Other useful accoutrements for the demonstrator are elbow length heavy leather gloves, and a heavy leather apron which goes down below your boot tops. If the apron doesn't cover your boot tops then leggings are a good idea too. (The last thing you want is some molten iron getting into your boots.)
4. Never do this demonstration above anything you would not risk igniting. I saw a demonstration years ago where the melt ran into a crucible embedded in a sand filled terra cotta flower pot sitting on an asbestos sheet on top of a lab bench. This may have seemed like adequate precautions but it was not. Due to some miscalculation the crucible overflowed, the iron somehow found its way through a crack in the baked sand to direct contact with the pot, from thermal shock the pot cracked, and collapsed, overturning the crucible, and there was enough iron present to run right off the asbestos sheet and set fire to the bench. Oops.
5. No-one should ever attempt a dangerous demonstration without a plan for what to do if it goes wrong. In this case, that means fire-fighting and first aid. However, unless you have access to Class D fire extinguisher, the only safe fire-fighting material is very dry sand, applied with a longhandled shovel. Obviously it will not extinguish the thermite but it will stop fire spreading into surrounding material until the thermite burns itself out. If you do get a thermite fire going and don't have any sand available, do not attempt to fight it. Just get everyone to safety and when the fire brigade arrives, make sure they know there's burning metal involved. --Securiger 09:08, 17 Jun 2005 (UTC)

This information should be added to Wikibooks: Thermite synthesis. --Yannick Gingras 06:52, August 28, 2005 (UTC)

Yeah, I was aware of the risk from moisture. I've heard that thermite can supposedly dissociate the hydrogen from water and ignite it- not an ideal scenario. As for making the materials from household items, I'd say that's an exercice in futility. Getting a fine, dry, pure powder from rusty nails/steel wool or filed pop cans is unlikely. I learned that the hard way. --Daveswagon 00:51, 19 Jun 2005 (UTC)

Oh trust me it works. Made it in 8th grade off the Anarchists cookbook. Tore up the sidewalk like hell. Used a DC trainset transformer, salt water, etc - Anon

It does burn very hot; when I made some, the dirt where it had been ignited remained burning for a few seconds after the thermite had gone out. The dirt had been turned to charcoal by the heat. As to making it with household materials, one source of fine aluminum powder is silver spray paint. The aluminum powder can be washed from the paint with acetone or paint thinner. As the above user mentioned, iron oxide can be prepared electrolytically (and then dried in an oven). As to thermite separating hydrogen from water, the aluminum does this. It's actually a kind of incomplete thermite reaction. The equation is: 2Al + 6H₂0 => 2Al(OH)₃ + 3H₂ -- Anon

Aluminium and Rust?

The ingredients I have noticed is aluminium and rust, a reactive metal and a metal oxide. But how would you keep the aluminium staying just that and not oxidizing itself because aluminium is so reactive and oxidizes. So wouldnt the reaction really be aluminium oxide and iron oxide? --Anon.

No, aluminium oxide and iron oxide would not react at all. As already mentioned in the article, a key point is that aluminium forms a passivation layer, so even though it is highly reactive it remains inert until melted. --Securiger 07:56, 4 October 2005 (UTC)

Atmospheric oxidation is sometimes a disadvantage of using very fine aluminum powders in thermites, but this oxidation only occurs at high temperatures after the thermite has been ignited and then only in areas where the thermite can contact air. Also, rust is not the best ingredient for thermite because it contains a mixture of iron oxides and hydroxides (Fe₂O₃, FeO(OH), Fe(OH)₃, etc).

Cleanup tag

I just added the clanup tag because it looks to me like it could be better worded.

I just changed it from Iron(II) oxide to Iron(III) oxide. Now I'm trying to document this and having trouble. Can someone find a reliable source for whther it shouldbe ferric or ferrous? (Sorry if I changed soemthing that was correct). RJFJR 14:29, 24 December 2005 (UTC)

I suppose ferric oxide could be used in a thermite reaction, but ferric oxide (rust) is much more commonly used. Iron (II, III) oxide (Fe₃O₄, magnetite) can also be used. A source is at http://chemed.chem.purdue.edu/demos/moviesheets/5.3.html, this seems fairly reliable and backs up ferric oxide.

Melt through concrete? is that possible?--XAdHominemx 21:37, 1 January 2006 (UTC)

I think this is an appropriate section for this discussion.--XAdHominemx 02:09, 2 January 2006 (UTC)

Yes, it's quite possible for concrete to melt, as was discovered during the investigation of the Chernobyl accident. Alphax ^τεχ 06:15, 21 January 2006 (UTC)