nerosrevenge Posted October 11, 2004 Share Posted October 11, 2004 Hi all. First let me say that I am new to Chemistry and after viewing the fountains of knowledge on the subject I have ultimate faith that someone will be able to help me. I have recently seen these "Flameless Heaters" used by Military and the like to heat their MRE's. According to what research I have been able to do, the pads used Iron Powder, Magnesium, Salt and Water. Apparently they will heat up to 220 degrees! I have an idea for an emergency heater using the same principal. My question is this: What amounts of each of these materials (more specifically what ratios) would you anticipate I would need to used to cause the desired reaction? Thanks so much, I look forward to all posts! Steve. Link to comment Share on other sites More sharing options...
YT2095 Posted October 12, 2004 Share Posted October 12, 2004 it`s similar to a controled Thermite reaction. if I rem correctly, it`ll be 25% Mg powder and 75% Fe2O3 (iron oxide aka rust) powder, the salt water is used as the ion carrier for the displacement exchange. I`m not sure what concentration of salt water is needed however. Link to comment Share on other sites More sharing options...
nerosrevenge Posted October 13, 2004 Author Share Posted October 13, 2004 Thanks so much YT! I guess I could try several variations until I get the desired effect. I'll post the results! Steve. Link to comment Share on other sites More sharing options...
nerosrevenge Posted October 15, 2004 Author Share Posted October 15, 2004 Is there another metal I could use instead of the magnesium? I have seen quite a few thermite related posts indicating aluminum (although I think magnesium is also required?!). Is it oxidation we're after? If so how do you think the aluminum would peform?? I'm not sure where I can get magnesium powder here (I'm in Canada). Any ideas?? Thanks, Steve. Link to comment Share on other sites More sharing options...
boris_73 Posted October 15, 2004 Share Posted October 15, 2004 yes for a thermite reaction you can just use iron oxide(rust) and aluminium 75% rust 25% aluminium, but i must warn you must not mess around with thermite it throws molten iron around once ignited and can reach temperatures of upto 3000c and the only time magnesium is used is in the form of magnesium strip which is used to ignite the mixture but you could just use a hand held turbo lighter tie it to a long stick and turn the lighter on it will ignite the mixture at a safe distance Link to comment Share on other sites More sharing options...
nerosrevenge Posted October 16, 2004 Author Share Posted October 16, 2004 Thanks for the info. Boris. For the purposes of my experiment I'm not certain that Iron Oxide will work!? If I understand the reaction correctly, once the water is added it triggers the accelerated oxidation of both the magnesium and the iron powder (causing heat) according to YT2095's post the salt acts as the ion carrier for the reation. If the iron is already oxidised (sp?) then only the magnesium (or aluminum) would react (if at all) and may not cause the desired reaction. I'm still not clear on whether aluminum would work in lieu of the magnesium?? Link to comment Share on other sites More sharing options...
jsatan Posted October 16, 2004 Share Posted October 16, 2004 Ignore boris_73 post seems to have missed the point. Link to comment Share on other sites More sharing options...
boris_73 Posted October 16, 2004 Share Posted October 16, 2004 ahh yes do ignore my post i just quickly scanned through the older ones and came across the word thermite then you asking about aluminium which goes with thermite and so i thought you wanted a thermite reaction sorry about that Link to comment Share on other sites More sharing options...
boris_73 Posted October 16, 2004 Share Posted October 16, 2004 i see you are talking about a controlled heat experiment one eg where zinc powder reacts with water to generate a exothermic reaction which is not capable of welding steel Link to comment Share on other sites More sharing options...
YT2095 Posted October 16, 2004 Share Posted October 16, 2004 as I mentioned in a prior post, it`s SIMILAR to a thermite reaction, in the exchange mechanism, it however ISN`T a thermite reaction and yes Alu powder will work, but you may need a weak acid to trigger it rather than just salt water, Alu`s hard to "fire" in a wet reaction, I`de reccomend a weak HCl soln for an Alu mix Link to comment Share on other sites More sharing options...
nerosrevenge Posted October 16, 2004 Author Share Posted October 16, 2004 I think using the alu is getting a bit too complicated. I want to keep this as simple and practical as possible. So, any crafty ideas on obtaining magnesium powder? Link to comment Share on other sites More sharing options...
boris_73 Posted October 17, 2004 Share Posted October 17, 2004 if you go to a camping shop you can buy firelighters which is a bar of magnesium just file it down, if they dont know what they are tell them you scrape the bar with steel and it produces sparks. or if that costs about £8 you might as well buy 50g of magnesium powder from http://www.kno3.com Link to comment Share on other sites More sharing options...
Gilded Posted October 17, 2004 Share Posted October 17, 2004 50g of magnesium is quite a lot, come to think of it. It's not even twice as heavy as water. Link to comment Share on other sites More sharing options...
boris_73 Posted October 17, 2004 Share Posted October 17, 2004 well 1ml of water weighs 1g so your telling me about 1cm3 of magnesium weighs 0.5g i never new that, huh its is true you learn something new every day Link to comment Share on other sites More sharing options...
boris_73 Posted October 17, 2004 Share Posted October 17, 2004 thats pretty cheap then i might buy some Link to comment Share on other sites More sharing options...
Gilded Posted October 17, 2004 Share Posted October 17, 2004 I mean't that it's heavier than water, but not even twice as heavy. I think it's 1.74 when water is 1. Still, very light if you ask me. Edit: Lithium, on the other hand, weighs about the 0.5g / cc you mentioned. Link to comment Share on other sites More sharing options...
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