Oh for christ sake. Can't you really figure this out yourself?
?
EX3 - 24-8-2003 at 03:25
wat i get
Al(NO3)3 or smting alseMadog - 24-8-2003 at 07:38
HNO3 doesnt attack Al, at least not with any easevulture - 24-8-2003 at 12:06
Highly concentrated HNO3 will not attack Al, 70% and below will.gritty_cryst - 24-8-2003 at 23:42
what is the explanation for that?a_bab - 25-8-2003 at 07:45
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".Madog - 25-8-2003 at 08:42
wow. i never knew that vulture - 25-8-2003 at 08:50
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.a_bab - 25-8-2003 at 11:28
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)
Sorry, my mistake. I meant to say SiC, which has a scale of 9,6. It scratches steel and ruby.a_bab - 25-8-2003 at 13:54
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.
?????????
EX3 - 28-8-2003 at 11:28
how can i make Al(NO3)3 ?????chemoleo - 28-8-2003 at 12:00
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.vulture - 28-8-2003 at 12:17
Try using 100% HNO3 and very pure Al powder. Then add a drop of Hg and duck for cover....Mumbles - 28-8-2003 at 14:42
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.vulture - 29-8-2003 at 09:55
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!
Another idea of mine hehe
chemoleo - 4-9-2003 at 11:53
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!
yes
Polverone - 4-9-2003 at 14:42
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]
purification of AlCl3
chemoleo - 4-9-2003 at 14:57
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?
Is that easier?
Polverone - 4-9-2003 at 15:08
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 chemoleo - 4-9-2003 at 15:22
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!!
that's a hard way to alcoholates
Polverone - 4-9-2003 at 16:42
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.chemoleo - 4-9-2003 at 17:30
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
It should react.
Nick F - 5-9-2003 at 03:07
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 .Polverone - 5-9-2003 at 08:24
When I added a few bits of magnesium sheet to plain dry methanol (no halogenated compounds) it reacted completely within a few hours at room
temperature, forming hydrogen and a sort of gel that I presume was magnesium methoxide.chemoleo - 5-9-2003 at 09:22
very nice how about Mg plus nitroethanol/methanol? should make an interesting
compound IPN - 5-9-2003 at 10:04
Add nitromethane to the magnesium methoxide, magnesium nitronate will precipitate and is easily filtered and dried.
Should be a interesting compound!!
forgot to mention
Polverone - 8-9-2003 at 14:29
For the AlCl3 creation, you're going to lose most of it as smoke if you just ignite CuCl2 with aluminum in the open! Sublimation is friend
and foe .chemoleo - 8-9-2003 at 14:47
yepp, I realised that later too.... so the whole thermite reaction got to be done in a closed container --> i.e. a little ceramic plate with the
mixture on top, and this whole thing plus fuse being in a large glass with lid + a tiny hole to allow hot air to escape of course Quite neat really, the AlCl3 is purified during the course of the reaction!verode - 1-1-2007 at 13:51
Quote:
Originally posted by EX3
Al + HNO3 = ....?
because the oxyde layer there's not reaction
but try to put some CuCl2 on it, you'll see ...
.