FeroAluminum Thermite

[jdurg]

cool' date=' thnx for the link.

 

U got your urianium turnings then? [/quote']

 

Yup. The stuff is so neat. Hard to believe that it's decaying right as we speak. So many times people talk about Uranium, but never really grasp that it's just a metal like most other metals. The fact that it's radioactive seems to outshine every other aspect of it. To compare its density, I took another vial of the same size and put similar sized magnesium ribbon strips in there. (Since the turnings are approximately the same size as the Mg ribbon I have). I couldn't believe how much heavier the Uranium was! I had to put a LOT more turnings in the Mg side to balance my makeshift 'balance'. (A ruler balanced on top of a rolling pin of sorts. If the two masses on either end are equal, it stays level. If not, it tilts). So this Uranium is indeed pretty danged dense.

[Lance]

Yup. The stuff is so neat. Hard to believe that it's decaying right as we speak. So many times people talk about Uranium, but never really grasp that it's just a metal like most other metals. The fact that it's radioactive seems to outshine every other aspect of it.

 

You have it all wrong, Uranium is a green solid or goo.

[d22k]

is the uranium denser than the precious metals/lead?

 

You have it all wrong, Uranium is a green solid or goo.

Tis true!! i saw it in the movieeess!

 

heh, i didnt end up doing any more tests last nite, my gf needed some attention, i should be able to tonight tho.

[YT2095]

heh, i didnt end up doing any more tests last nite, my gf needed some attention.

 

I`m disapointed in you, tell her who`s Boss and that Science comes 1`st

 

and yes, it is green, there`s a great picture of the stuff in the Simsons!

[d22k]

well i tried that, then she beat me up

[YT2095]

aha! hence the need for Thermite!

 

Good Man

[d22k]

SHHHH!!! if she hears that my carefully laid plans will go to waste!

[jdurg]

The Uranium has a density of about 19 g/cc, so it's about as dense as gold and tungsten are.

[d22k]

tungsten ay?

learn something new every day ;0

[Gilded]

"and yes, it is green, there`s a great picture of the stuff in the Simsons!"

 

It's not uranium in the Simpsons, it's plutonium! A man of your age should know his Simpsons.

 

Btw jdurg, ever thought about founding Element Collectors' Association?

[David_8956]

Update:

At this point' date=' i thought, 'What have i got to loose?' and decided to go the other way, so i mixed it up as 8:3 That being 8 parts IronOxide, to 3 parts aluminium.

The results were, needless to say, spectacular, and the reaction was many times brighter and more violent than the prvious attempts, even though i was using about 1/2 the amount of thermite.

 

Can anyone shed any light as to why this is? when all reason would suggest it should have been the other way around....

James[/quote']

 

Because theorey actually suggests 3:8 (Al:Fe2O3) is the correct ratio, not the other way round. YT2095 obviously does not know what he is talking about or maybe he just made a mistake. I will explain how you can calculate the correct ratio.

 

Firstly write down the chemical equation as follows:

 

Al + Fe2O3 = Al2O3 + Fe

 

You can work out the equation because you know the reactants and then the products are obvious because you know the iron oxide acts as an oxidiser and oxidises the aluminium to form aluminium oxide. Also the aluminium reduces the iron oxide to produce molton iron. If you do not know the formula of aluminium oxide you can work this out using oxidation states. The formula for aluminium oxide is Al2O3 because the oxidation state of aluminium in all it's compounds is +3, and the oxidation state of Oxygen is -2. You just need to balance these and you should get the formula Al2O3.

 

Next you need to balace the chemical equation:

 

2Al + Fe2O3 = Al2O3 + 2Fe

 

So you know that 2 moles of aluminium will react with 1 mole of iron oxide, next you need to work out how much 1 mole of each weighs.

 

1 mole of aluminium = 27.0g (from periodic table)

1 mole of Fe2O3 = 159.6g (55.8*2) + (16*3) (from periodic table)

 

So you have 2 moles of aluminium (54g) reacting with 1 mole of Fe2O3 (159.6g)

 

You can now work out the percentage of aluminium by dividing 54g by the total weight 213.6 (54+159.6) and then multiplying by 100, to get 25.28%

 

So the percentage of aluminium in the thermite composition is 25.28%, and the percentage of Iron (III) Oxide is 74.72%. This approximates to a ratio of 3:8

[rthmjohn]

Hey, d22k. How accurate is the scale you're using? A more accurate ratio is 2.89 parts of Fe2O3 to 1 part of Al... with a good scale, you can way out more precise amounts of ingredients and thus make better mixtures of thermite.

[rthmjohn]

This guy on ebay claims that his aluminum powder is 99.5% pure and 1000 mesh. He's selling ONE POUND for eight dollars... Does that sound like a scam to you? Another guy is selling his supposed 3000 mesh for $35.99/lb. He claims it's the best for pyrotechnic formulas. Would I get unwanted attention from homeland security if i bought some of his stuff?

[rthmjohn]

btw, what is the minimum mesh of aluminum for a successful thermite reaction?

[David_8956]

btw, what is the minimum mesh of aluminum for a successful thermite reaction?

 

I've managed to get a succesful thermite reaction from some quite course aluminium powder, i'm not sure on the exact mesh but i believe it was about 250.

 

If you are using aluminium powder of this mesh you will reallly need to have a layer of magnesium powder over the top of all the thermite just to make sure the temperature is hot enough for all the thermite to react. If you are using aluminium powder of 350 mesh or higher it will work fine, and you can easily ignite it with magnesium ribbon or a sparkler.

 

I have used 2000 mesh aluminium in thermite before but i think the courser stuff is a lot better (350-450) because it lasts longer and so the target is in contact with the thermite for much longer so more heat is transfered to it, rather than to the surroundings. Also if you have aluminium of a high mesh it is a waste using it in thermite there are far better uses for 2000 mesh aluminium powder.

[rthmjohn]

Damn... I've used almost all my 3000 mesh on thermite, what a waste... I plan on buying some 625 mesh though and maybe I can use the rest of my 3000 in flash compositions. Btw, I made a mixture of about 2.5 parts Al to 1 part KMnO4 (a flash mixture I presume) and after I lit it examined the products. I found this bluish green stuff that dissolved in water. Also, my gloves were stained by a brown compound when I retrieved the sample. What were these compounds?

[David_8956]

Damn... I've used almost all my 3000 mesh on thermite, what a waste... I plan on buying some 625 mesh though and maybe I can use the rest of my 3000 in flash compositions. Btw, I made a mixture of about 2.5 parts Al to 1 part KMnO4 (a flash mixture I presume) and after I lit it examined the products. I found this bluish green stuff that dissolved in water. Also, my gloves were stained by a brown compound when I retrieved the sample. What were these compounds?

 

The 625 mesh aluminium should be good for making thermite with, i'd definatly save your 3000 mesh aluminium for flash compositions though, it will not be wasted using it in flash comps.

 

I'm not totally sure on this but i'm fairly confident that the bluish green stuff that is soluble in water you describe is potassium manganate (K2MnO4). The compound that stained your gloves brown is most likley manganese(IV) oxide (MnO2). KMnO4 is very easily oxidised to MnO2 if it comes in contact with your skin or other surfaces which is why it stains everything brown so it could have also been unreacted KMnO4 or simply KMnO4 that you got on your gloves when mixing the chemicals.

 

If you are using the remains of your 3000 mesh aluminium to make flash comps, i would recommend you use potassium perchlorate if this available to you. In my experience it makes far superior flash to permanganate based stuff and is quite a bit more powerfull. I also prefer to work with perchlorate since it is a lot less messy than permanganate and doesn't stain everything brown.

[rthmjohn]

I believe the equation is as follows: 6 KMnO4 + 14 Al --> 3K2O + 7Al2O3 + 6 Mn. I don't think the blue stuff is permanganate though...