kazaa81
Hazard to Others
Posts: 368
Registered: 30-4-2004
Member Is Offline
Mood: ok
|
|
AlCl3 experiments...
Hallo to all,
I was trying to make some AlCl3 but, something wrong has occurred.
I've dissolved Al foils in 10% HCl and then wait the H2 evolving.
After a while, I've put the colorless liquid in a beaker and put all in a bath of hot water. The water of AlCl3 solution doesn't seem to
evaporate, but the solution has becomed yellow.
Because the hot wasn't sufficient to evaporate the water, I've put the solution in a steel container and then put it on a flame heat source.
The solution was boiling, becoming green, and nasty fumes has evolved....I've tried to evaporate almost all the liquid, except a small quantity,
but only nasty fumes evolved and any solid has come out of the green solution.
Can anyone explain what has occurred and in what way can I obtain solid crystalline AlCl3?
Thanks at all for help 
|
|
|
BromicAcid
International Hazard
Posts: 3227
Registered: 13-7-2003
Location: Wisconsin
Member Is Offline
Mood: Rock n' Roll
|
|
If you are trying to get anhydrous AlCl3 you won't be able to do it by this method, AlCl3*6H2O is possible, but this decomposes on heating past
100C to water, hydrogen chloride, and aluminum oxychloride products.
Your mixture probably started eating your steel container and since you were heating it originally on a bath of hot water and AlCl3(aq) is a boiling
point elevator it's no wonder your solution didn't appear to be shrinking in volume. If you keep it pure (well, you're using aluminum
foil, that might be a problem) then you might be able to get AlCl3*6H2O to crystallize out, but then again my handbook of chemistry and physics
doesn't even say how soluble AlCl3*6H2O is, it only says very soluble, it itself it disquecent and decomposes @100 so it looks difficult,
AlCl3*6H2O is normally made by recrystalizing anhydrous AlCl3 from concentrated HCl solutions.
There are a few interesting posts on this from sci.chem avalible by searching the google groups for aluminum chloride decomposition.
|
|
|
kazaa81
Hazard to Others
Posts: 368
Registered: 30-4-2004
Member Is Offline
Mood: ok
|
|
Questions...
Hallo Bromic,
thanks for help!
Why aliminium foils are a problem? They're used for food and, for this, has a purity of 99+%.....
Then, how can I obtain solid AlCl3 from dissolved Al in 30% HCl?
And, very important, I've some CuCl2*H2O (green hydrated copper chloride) solution, how can I let it to evaporate with having the green crystals
as final product.
Does the two carefully evaporation processes has any similar thing?
Thanks for help very much!
|
|
|
BromicAcid
International Hazard
Posts: 3227
Registered: 13-7-2003
Location: Wisconsin
Member Is Offline
Mood: Rock n' Roll
|
|
| Quote: | | Why aliminium foils are a problem? |
As has been said many times before, you ever notice how one side of the
foil is shiny and the other somewhat dull? If it were pure foil both sides would have equal luster, as it is most companies treat one side with
polymers or by strictly chemical means to protect the foil more and hold it together better so it contains a minor impurity.
Assuming you are talking about obtaining the hydrated chlorides (I already said making anhydrous AlCl3 from aluminum chloride solutions is next to
impossible and copperic chloride also decomposes somewhat on dehydrating) then they could probably be obtained by placing the solution in a
desiccator, or by prolonged heating below their decomposition point.
With CuCl2 solutoins you could just heat and heat and heat the solution and drive off the water they CuCl2*2H2O decomposes but not considerably during
the dehydration, but with the AlCl3 solutions it's either careful prolonged heating or in a desiccator.
Plus a thread on this already exists, HCl and Al, AlCl3? please use the search function more in the future.
[Edited on 12/5/2004 by BromicAcid]
|
|
|
garage chemist
chemical wizard
Posts: 1803
Registered: 16-8-2004
Location: Germany
Member Is Offline
Mood: No Mood
|
|
Aluminium foil is nearly pure aluminium (98%+), the dull and shiny side have another cause:
Aluminium foil is made by flattening out sheet aluminium in several phases, each reducing the thickness.
It is passed through pairs of rotating steel wheels with reducing distances, this makes it flat.
During the last phase, where the final product is produced, two sheets are passed through the wheels at the same time.
The side where the aluminium touches the wheels becomes shiny, the sides where the two aluminium foils touch each other become dull, because they have
the same hardness and become pressed "into each other" a bit.
Aluminium foil can be regarded as a source of reasonably pure aluminium for the hobby chemist.
It only contains a few tenths of percents of alloy metals, which increase its strength.
Pure aluminium has no use as a construction metal.
|
|
|
BromicAcid
International Hazard
Posts: 3227
Registered: 13-7-2003
Location: Wisconsin
Member Is Offline
Mood: Rock n' Roll
|
|
I thought that aluminum had a coating, whenver I used to dissolve large quantites of it in dillute HCl and left it undisturbed there would be a
structure in the place where the aluminum was, like a sheaded skin of a snake, I guess it could be other metals or oxides or impurities in the foil
that leave the 'ghost' shape of the aluminum behind but I assumed it was some sort of coating. My steel wool for sanding paint does the
same thing to a greater degree.
I have seen people say there is no coating, and others say there is, personally it's never been an issue with me.
|
|
|
garage chemist
chemical wizard
Posts: 1803
Registered: 16-8-2004
Location: Germany
Member Is Offline
Mood: No Mood
|
|
It's possible that your aluminium foil has a plastic coating, my aluminium foil has none, but that entirely depends on the brand.
Just hold a piece of the foil into a flame, if it burns/chars, there's a coating.
Maybe switch to another brand?
|
|
|
kazaa81
Hazard to Others
Posts: 368
Registered: 30-4-2004
Member Is Offline
Mood: ok
|
|
White cake...
Hallo to all,
I've dissolved some Al in hot 30% HCl and, this time, the reaction between Al and HCl has started soon, due to the temp. of HCl which was higher
than the previous time.
But, after very much Al has dissolved and H2 formed, a white cake in the bottom of the beaker has formed.
Is it an hydride or AlCl3 undissolved due to the minor H2O present in the solution?
Thanks at all for help
|
|
|
Tweenk
Harmless
Posts: 15
Registered: 7-12-2004
Location: Poland
Member Is Offline
Mood: safety-consciou
|
|
I think this is aluminium hydroxide. By dissolving a protective layer of Al2O3 (which always exists on Al) in HCl, you allowed water to react with
metallic aluminium, which turned into Al(OH)3 (This also liberates hydrogen). This precipitate should disappear (dissolve) when excess acid is added
if I'm right. You had too much water present in the HCl for AlCl3 not to dissolve.
And now we add powdered sugar to the previously liquefied chlorine dioxide...
|
|
|
kazaa81
Hazard to Others
Posts: 368
Registered: 30-4-2004
Member Is Offline
Mood: ok
|
|
Disappoint....
Thanks for help,
but I'm not full sure of what you've sayed.
The 'possible' Al(OH)3 is very much for be derived from the thin Al oxide layer.....what is the soluble data of AlCl3 and Al(OH)3? This will
help for this questions!
Thanks for help
|
|
|
BromicAcid
International Hazard
Posts: 3227
Registered: 13-7-2003
Location: Wisconsin
Member Is Offline
Mood: Rock n' Roll
|
|
Please don't ask for solubilities, they can usually be easily found with google.
Aluminum chloride hexahydrate though seems to be difficult to find a solubility on, my old CRC doesn't give a number for the solubility, just
states that it's very soluble.
ChemDAT says 44.9 g / 100 ml
This solubility chart claims 70 g / 100 ml although it doesn't state if it is the hydrate or the anhydride, however the anhydride would react
so it's probably the hydrate.
This site states that 100 ml of water could dissolve over 100 g aluminum chloride.
MSDS for aluminum chloride hexahydrate listing the solubility as 45.6 g / 100 ml @ 20C
Never the less, looking up solubilities is usually easy on google, give it a shot next time.
[Edited on 12/8/2004 by BromicAcid]
|
|
|
alchemie
Harmless
Posts: 36
Registered: 4-6-2003
Member Is Offline
Mood: variational
|
|
AlCl3*6H2O is not very soluble in concentrated HCl.
I have seen a procedure somewhere in wich they say to dissolve the Al in the minimum amount of conc. HCl and pass HCl gas to precipitate the
AlCl3*6H2O.
I´ll try and find the procedure again and post it.
|
|
|
JohnWW
International Hazard
Posts: 2849
Registered: 27-7-2004
Location: New Zealand
Member Is Offline
Mood: No Mood
|
|
"Pure aluminium has no use as a construction material" (Garage Chemist).
This is not quite correct. Pure Al is much less susceptible to electrolytic corrosion than Al alloys, although is not as strong as commercial Al
alloys with Si and Mg etc. So, articles made of Al alloys are sometimes clad in pure Al, either by dipping in molten pure Al, or by resistance-welding
sheets of pure Al onto them.
|
|
|
kazaa81
Hazard to Others
Posts: 368
Registered: 30-4-2004
Member Is Offline
Mood: ok
|
|
What Al compound.......?
Hallo to all,
what compound is obtained if i put a solution of an Al water soluble salt in aqueous NH3? I've obtained a strange thick gel. I've filtered
some of it.
What compound is this, what propreties has and what can made from it?
Thanks at all and merry Christmas
|
|
|
FloridaAlchemist
Hazard to Self
Posts: 76
Registered: 8-6-2003
Location: USA
Member Is Offline
Mood: No Mood
|
|
Possible Aluminum Chloride Synthesis
Might want to try combining saturated hot solutions of Aluminum Sulfate and Calcium Chloride.
This should give you Aluminum Chloride Solution and Calcium Sulfate precipitate.
Filter while still hot to get rid of the Calcium Sulfate then immerse the hot saturated Aluminum Chloride Solution in a ice bath to force
crystallization of the Aluminum Chloride.
|
|
|
FloridaAlchemist
Hazard to Self
Posts: 76
Registered: 8-6-2003
Location: USA
Member Is Offline
Mood: No Mood
|
|
Aluminum Chloride Synthesis
The preceding synthesis is for the hydrated form of Aluminum Chloride.
If its the anhydrous Aluminum Chloride you need a different method is reqiured.
|
|
|
kazaa81
Hazard to Others
Posts: 368
Registered: 30-4-2004
Member Is Offline
Mood: ok
|
|
Ok...
Ok, good.
But the last question wasn't how to made anhydrous AlCl3......
Have a good day...
|
|
|
FloridaAlchemist
Hazard to Self
Posts: 76
Registered: 8-6-2003
Location: USA
Member Is Offline
Mood: No Mood
|
|
| Quote: | Originally posted by kazaa81
Hallo to all,
what compound is obtained if i put a solution of an Al water soluble salt in aqueous NH3? I've obtained a strange thick gel. I've filtered
some of it.
What compound is this, what propreties has and what can made from it?
Thanks at all and merry Christmas |
If you 1st boil the aluminum salt with Ammonia then precipitate the product and dry it at 100'C you will have hydrated aluminum oxide Al2O3 . H20
If this is then heated to dull redness, aluminum oxide is left.
|
|
|
Pyridinium
Hazard to Others
Posts: 258
Registered: 18-5-2005
Location: USA
Member Is Offline
Mood: cupric
|
|
| Quote: | Originally posted by BromicAcid
it itself it disquecent and decomposes @100 so it looks difficult, AlCl3*6H2O is normally made by recrystalizing anhydrous AlCl3 from concentrated HCl
solutions.
There are a few interesting posts on this from sci.chem avalible by searching the google groups for aluminum chloride decomposition.
|
Deliquescent AND unstable... that's a tough one. Evaporate under reduced pressure at room temperature, probably. Once you got the volume down
enough, you could try chilling it to make crystals form.
I noticed putting the solution in the sun will even cause it to turn deep yellow. No good.
I prepared some of the aluminium oxychloride by evaporating the AlCl3 solution to dryness. The residue doesn't come out of the glassware too
well... actually it doesn't come out at all.
I think the powder I collected is a chemical mess with no definite formula.
I did read somewhere that it could be used as a coagulant, but for what I don't yet know.
The oxychloride will produce the hydroxide when treated with strong NaOH. Probably NaCl is formed, not sure.
Not sure what use the oxychloride would have for experiments.
|
|
|
govinda
Unregistered
Posts: N/A
Registered: N/A
Member Is Offline
|
|
recrystallization of AlCl3.6H2O
[How can i prepare the hexa hydrated aluminium chloride from it's solution ? reply soon.i am confusing here that it is again decompose at 100degree
centigrade.]Originally posted by govinda
|
|
|
chloric1
International Hazard
Posts: 1070
Registered: 8-10-2003
Location: GroupVII of the periodic table
Member Is Offline
Mood: Stoichiometrically Balanced
|
|
Reduce solubility
Reduced pressure might work out but If I am not mistaken HCl lowers AlCl3-6H2O solubility. I remember 12 years ago I dissolved aluminum picture
hanging wire in fairly strong HCl but not fuming HCl. I poured the solution in a shallow dish and a week later I had wet prismatic needleshaped
crystals. A dessicator at reduced pressure may help you obtain a less damp product.
Fellow molecular manipulator
|
|
|
![[*]](images/xpblue/default_icon.gif){kind=icon}
