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EX3
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Al + HNO3
Al + HNO3 = ....?
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vulture
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Oh for christ sake. Can't you really figure this out yourself?
One shouldn't accept or resort to the mutilation of science to appease the mentally impaired.
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EX3
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?
wat i get
Al(NO3)3 or smting alse
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Madog
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HNO3 doesnt attack Al, at least not with any ease
Most people outgrow their pyro tendencies, we are the ones who\'s tendencies outgrew us.
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vulture
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Highly concentrated HNO3 will not attack Al, 70% and below will.
One shouldn't accept or resort to the mutilation of science to appease the mentally impaired.
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gritty_cryst
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what is the explanation for that?
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a_bab
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Well gritty_cryst, that's a MUCH better question than the whole topic, so I'll reply.
As you know, HNO3 is an acid with strong oxidant properties. It will attack copper very easy, even if copper is less reactive than H. It does this by
first oxidising the copper, then reacting with the oxide to form the copper nitrate.
The general idea is that if the nitric acid is concentrated enough, it'll attack the metal to form the correspondent oxide, rather than the
nitrate. Of course, the oxide will be later converted to the nitrate, so you'll be left in the end with water and the nitrate salt. The process
is done layer by layer until all the metal gets consumed.
BUT the Al2O3 is notorious unreactive. Very hard to fuse. The toughness is close to the diamond one (ruby). The crystaline structure is a very compact
one. So, the nitric acid (if concentrated enough as Vulture said) will not be able to penetrate the Al oxide layer. In other words, the Al gets
"passive".
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Madog
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wow. i never knew that 
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vulture
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That's not really the correct explanation.
Metals that are to the left of hydrogen in the electrochemistry row, that means they are stronger reducers than hydrogen, will evolve hydrogen gas
with nitric acid, because H+ then acts as an oxidizer.
With metals less reactive than hydrogen, the nitrate ion will act as an oxidizer, being reduced to NO.
The reason Al and other reactive metals are not easily attacked by concentrated acid is because concentrated acid does not contain free H+ and because
Al compounds tend to get imbedded in the metal structure. This phenomenon is also known with Iron. Except for Iron oxide ofcourse.
BTW, pure SiO2, quarz, is the second "strongest" material next to diamond.
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a_bab
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Yes Vulture, you are right. But having he's level of knowledge, I tried to be as simple as possible 
As about the diamond, I'm sorry but your affirmation is not true at all. SiO2 hardness is a degree bigger than glass; that is only about 7 at the
Mohs scale of hardness. There are lots of other compounds much harder than the diamond (end even harder, like the borazone)
Mohs scale
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vulture
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Sorry, my mistake. I meant to say SiC, which has a scale of 9,6. It scratches steel and ruby.
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a_bab
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Yeah, carborundum or silicon carbide. Extremly hard, hard to fuse, innert to the most agressive chemicals... (of course, HF will do the job).
Still, borazone is the hardest, so SiC would be the third.
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EX3
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?????????
how can i make Al(NO3)3 ?????
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chemoleo
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lol... i guess dissolve Al in hNo3 and dry it. but you wont get H2O-free Al(NO3)3, it will be a hexahydrate or sumthing. If you heat it up too much ,
it's going to decompose, just as aluminium chloride hydrate does.
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vulture
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Try using 100% HNO3 and very pure Al powder. Then add a drop of Hg and duck for cover....
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Mumbles
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Try mixing solutions of Aluminum Sulfate and Calcium Nitrate. Theoretically the Calcium Sulfate should precipitate out of the solution, leaving you
with a Aluminum Nitrate solution. Upon drying you will get a hydrated form.
If its necesary to have the anhydrous form fuse Aluminum Sulfate and Potassium Nitrate together. Crush up the product. Dissolve as much product as
you can in Acetone or anhydrous alcohol. Aluminum Nitrate is quite soluble in both. As far as I can find any other products are not soluble in those
solvents.
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vulture
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If your reagents aren't soluble in your solvent, the fact that your product is, is absolutely of no use, since it won't form!
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chemoleo
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Another idea of mine hehe
yo, as AlCl3 (anhydrous) is an extremely useful compound (esp. in org. syntheses, and for dehydration) I thought of this:
3 CuCl2 (anhydr) (or FeCl3 etc) + 2 Al --> ignition with sparkling candles/Mg ribbon --> 2 AlCl3 + 3 Cu
I dont see why this shouldnt work! Normal aluminothermic reaction! Sweet ey?
PS probably would be hard to seperate this from the Cu, but dont think it would be a problem. Will try this soon!
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Polverone
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yes
That reaction does work. It's not especially vigorous, compared to oxide-based mixtures, but it works well enough. It'll go if you put CuCl2
powder in Al foil and roll it up into a little tube. Only a few seconds of match flame exposure is needed to start the reaction. I haven't
figured out how to separate pure, anhydrous AlCl3 from the reaction products, though.
Edit:
Whoops, I know how to purify it: sublimation! Unlike AlCl3, Al (s) and CuCl2 aren't very particularly volatile. Avoiding moisture exposure may be
tough unless you're careful with the sublimation setup. I think Vogel may have something to say about purifying AlCl3 by sublimation.
[Edited on 9-4-2003 by Polverone]
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chemoleo
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purification of AlCl3
yes, I just checked Mercks Chemdat.
AlCl3 sublimes at 181 deg C, and decomposes (into what?) at 262 deg C.
However there is a better way 
It is soluble in various organic solvents! I.e soluble in anhydrous ethanol (I wonder tho whether it would react with it to form an alcoholate), as
well as chloroform (but only 0.72g/l). There wasnt info on other solvents tho. Anyone know more?
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Polverone
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Is that easier?
It depends on what you have available, I suppose. For sublimation you only need enough glassware to sublime the AlCl3. For organic solvents you need
completely dry liquids plus enough glassware to distill the solvent off while still protetcting the AlCl3 from air. Hmm, actually, for the really
rough and cheap chemist: what about putting the CuCl2/Al reaction products in a previously oven/flame dried glass bottle with a narrow neck (like a
wine vinegar bottle), sealing the bottle, heating the bottom and cooling the neck, and rapidly scraping out the sublimed material into a dry bottle
with a tight seal when the sublimation is complete? "Mostly anhydrous" should be good enough for most applications anyway
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chemoleo
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yah, I guess both methods have their merits.
I wouldnt use a wine bottle tho as it is unlikely to bear the temperature differences across the bottle if u heat the bottom and cool the top. Shit I
wish I had access to my lab right now, and I would try it.
Also, do you think AlCl3 would react with EtOH (or any other alcohol) to form Al(OC2H5)3??
This would be a nice route for synthesis of a lot of very very interesting compounds! I seem to recollect that Napalms (!!) are aluminium alcoholates,
so here we go!!
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Polverone
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that's a hard way to alcoholates
If it works, it still sounds like a lot of effort! Can't you just use a bit of Hg or an Hg salt to form an amalgam on the surface of Al, then
react that with your alcohol? Of course, if you can't get Hg or its salts, that's another problem.
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chemoleo
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yeah, for me its hard to get Hg.. they dont have this in a biochem lab.... 
Are u sure that the Hg trick would work however? I know it exposes atomic Al (as opposed to Al2o3 rendering the underlying Al inaccessible). But does
it then react with alcohols or are u speculating? Nice idea, anyhow
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Nick F
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It should react.
I think Al amalgam will form alcoholates. IIRC Marvin said over at Roguesci that Mg turnings in excess anh. alcohol, with some chlorocarbon solvent to
start the reaction (how's it do that?) will go to completion...
It didn't work when I tried it, however I didn't use much care at all. Mg scraped from 96% Mg, 3% Al, 1% Zn scrap were put into some meths
and I added some paint stripper that I knew contained DCM. Pretty ghetto-style  .
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