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m1tanker78
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Neil, to answer your question, I didn't use chloride flux in the melt. In fact, I didn't add anything at all except Al bits of high purity. These high
purity ingots will be used to make 'designer' alloys at a later date so I accepted a slight loss of Al in the slag.
That's also the reason I chose this lot for this experiment. I wanted to remove as many ?'s as possible. The surfactants they add to household ammonia
drive me up the wall (almost as much as the smell). Also, Al foil is far from pure and has tricked me in the past.
I'm trying to digest everything since Al chemistry is mostly new to me. I have a clear solution that has turned somewhat viscous (not gelatinous). If
I filter the bits out and heat the solution, NH3 will escape along with water. Eventually, Al(OH)3 will lose water, first forming AlO(OH), and
finally, Al2O3. If that's correct then why can't this be exploited as a path to quantifying the amount of Al present in slag or in AJOKER's
case, burnt aluminum? I don't believe Al2O3 reacts appreciably (if at all) with NH4OH or NH3 in aqueous solution. I know that stronger
alkalis could be used but the attractive side of ammonia is that it completely evaporates, allowing a sample to be dried and weighed without
significant influence from other ionic salts.
One thing that's bugged me for a while...
Wiki's Al2O3 page says alumina is insoluble in water - OK. It also says Al2O3 is 'very hygroscopic'. Is this a typo? I've always been
under the impression that alumina is extremely stable in air and moisture.
Tank
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Neil
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Quote: Originally posted by AJKOER  | Actually, I find fascinating the tenacity of theorists!
I agree with the safety of Al container storage for NH3. However, this is not the case for NH3+H2O (I read on a NASA site once of a NH3/Al tubing
system that also mentioned in the event of moisture entering the system, a corrosive reaction could occur).
The sad truth is that anyone who ever has owned anything Aluminum knows (and a 2 minute internet search more than confirms) you cannot clean Aluminum
products with household ammonia (it causes pits).
As a chemist, you should know that this means that household ammonia (or its detergents? really) therefore dissolves/attacks the protective Al2O3
coating (or the 2% impurities which vary from Si, Fe, Mg and Mn?). This most likely means a chemical reaction given the resistance of protective
layer. One model (the least complex given the near entirely with which Al eventually dissolves) is the formation of an Aluminum ammonium complex that
exposes the underlying Al which readily reacts with H2O to produce H2 (Source: See "Concise Encyclopedia Chemistry" by deGruyter or search the web).
An undisclosed source on another forum states that the NH3 acts as a catalyst in the dissolving of Al with NH4OH with the release of H2 (which was
confirmed by the forum's author). I will see if I can obtain the actual source, but I am not expecting more than a casual reference.
I would advise you read the google book's entire section on Al2O3 and the other article that dates from 1940, good stuff!
[Edited on 21-6-2011 by AJKOER] |
Your condescending attitude is very much appreciated, thank you.
Household ammonia should not be used to clean aluminum ergo Ammonia causes pitting to Aluminum by removing its oxide coat is absurd. That is a logical
fallacy based on far to little knowledge.
Cleaning implies you are removing a unwanted substance, what are the chances that 100% of the time that an aluminum surface, which is in need of
cleaning, will have no traces of halites or phosphates on it?
What are the chances that relatively crude cleaning ammonia is free of any contaminates or do you clean your counters with analytical grade ammonia?
To be trite, I will now preform an experiment following your methodology. I saw a man who resembled Elvis, to verify that this is Elvis I will now
Google "Elvis is alive, proof, pictures" I now have have proof Elvis is alive.
The undisclosed forum to which you refer, and to which you post the entries you post here verbatim, does not by mystical fortune confer objectivity or
legitimacy to your claims in and of its self.
As a student of the Humanities and of Science I know that anything can appear true if you solely look for validation.
As a Student of Chemistry I know that chemists are individuals who have well studied and examined many reactions in many situations. I know from
experience that Gert is exceptionally good with his mathematical analytical skills. I also know that he is not right 100% of the time and that he does
not know everything, who does? While he may deliver his opinions with a sledge hammer, as a student of chemistry I know that they carry far more
weight then my own deductions by virtue of his experience and education.
I refer you to this
http://books.google.ca/books?id=0CYdprLzfMoC&pg=PA611&am...
This
http://www.usmotors.com/Products/ProFacts/tableof.htm
This
http://www.springerlink.com/content/jj5t8210k44g1u33/
This
http://www.dynonobel.com/files/2010/04/1130-Aqua-Ammonia-09-... (what aluminum is not an incompatible?)
This
http://home.comcast.net/~pchristou/docs/silhoutes.pdf
and so on.
Here is a test, take aluminum foil and blow torch it with an oxidizing butane flame and then test for residual Al with NaOH.
No matter how much fuel you waste you will never get all of the aluminum to convert to an oxide. The Aluminum has to high of a boiling point to fume
out and burn, and the alumina has to high of a melting point to let the aluminum out to oxidize. if you use Draino, the reaction with Al will produce
some ammonia gas which you can test for with litmus paper.
So, lets say that Al2O3 may have nothing to do with the observed reaction. What happens if we rough up some Al foil and toss it in Ammonia and heat
the ammonia? Nothing. What about if we take the sand paper and rub off some of the garnet sand and add that? Nothing. so aluminum and ammonia did not
react, nor did garnet and ammonia. Ladies fear not, Windex will not dissolve your rubies.
What if we add some KCl? slow gas production is observed originating from the scratches on the Al foil. increased heat causes an
increase in reactions.
Now, I did test the gas from the burnt Al foil. I washed it with HCl, which did not become cloudy and did not dissolve any of the gas. A flame test
gave a very energetic fire ball, which suggests Hydrogen.
I got the exact same reaction for plain aluminum foil in the same ammonia solution with KCl.
So where does that leave us?
http://proj3.sinica.edu.tw/~chem/servxx6/files/paper_7425_12...
From above:
"The complex characteristics and mechanisms of aluminum pitting corrosion in a solar heating system
were studied by the chemical immersion method and electrochemical techniques as well as fractal theory.
The results showed that pitting corrosion of Al occurred in a tap water environment due to the local enrichment
of Cl- ions."
There are many routes to pitting Al that do not involve digesting its oxide. Without making an effort to determine if any of these are active the
assumption that the ammonium is somehow reacting with the oxide is baseless and poor science.
What is interesting is that using pure ingredients m1tanker78 has what is at least a very similar reaction. (One last grasp for a straw, did you use a
de-gassing agent?)
I did not observe any cloudy formations when the captured gas was brought near HCl, which suggests that it was ether consumed or otherwise diverted
from the captured gas.
What seems more likely to me is that when Al is heated to generate a thick oxide skin, the skin is more vulnerable to cracking which exposes fresh
metal. The fresh metal would be able to react with the water producing hydrogen and possibly a complex as it transitions to becoming an insoluble
hydroxide which could form a gel.
As to Al2O3 my understanding is that it's hygroscopic tendencies disappear once it has been calcined similar to the tendency of CaSO4 to cease
absorbing water once it has been calcined at more then 450F. Both substances experience crystal phase changes which create a more water resistant
form.
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m1tanker78
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| Quote: | | What seems more likely to me is that when Al is heated to generate a thick oxide skin, the skin is more vulnerable to cracking which exposes fresh
metal. The fresh metal would be able to react with the water producing hydrogen and possibly a complex as it transitions to becoming an insoluble
hydroxide which could form a gel. |
This could certainly be the case. However, my belief is that the solvent (aq. ammonia) is simply migrating through the porous oxide - very slowly.
After all, heavy Al anodizing is performed in this way but usually in acidic solution. Regardless, the liquid must migrate through the pores somehow.
This probably also contributes to the observation of near equal rates of reaction in dilute ammonia water and concentrated ammonia water.
Neil, it's worth mentioning that Al foil manufacturers usually coat the foil in a protective wax (or other similar substance). Other than that, I
don't have a good explanation of why your foil didn't produce any bubbles. My observations are identical to what AJOKER described in the OP. Try
tearing the foil into small pieces and look for bubbling at the edges.
Tank
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AJKOER
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I found an interesting reference on one of the slides titled "Presence of Aluminum Nitride in Salt Cake" presented by the Global Symposium on
Recycling, Waste Treatment and Clean Technology in Ocober 2008, Cancun, Mexico. In essence, the dissolving of AlN produces ammonia that raises the pH
which "dissolves the alumina film on unrecovered Aluminum particles surface, thereby exposing the Al surface to the reaction Al + H2O -->
Al(OH)3 + H2"
One could read this as the NH3 is directly responsible for dissolving the Al2O3 as the pH is raised, or as the salt cake has NaCl, KCl, MgAl2O4 and
oxides of Fe, Si and Zn, these in the presence of a higher pH are responsible.
Link: http://www.es.anl.gov/Energy_systems/docs/process_tech/indus...
As a sidebar, I also observed that leaving Al foil in vinegar for a few hours, even if apparently unreacted, does speed up the speed of the reaction
after the Al foil has been wash and placed into NH4OH. I got this trick from an Al Foil Coating manufacture article that lamented the power of acetic
acid to pierce through all their efforts to make the Al foil unreactive.
Here is the link on the NASA use of anhydrous NH3 with Al piping:
http://www.nasa.gov/offices/oce/llis/0698.html
Also from the cited reference: "Corrosion resistant materials handbook By D. J. De Renzo, Ibert Mellan", page 611, it appears with respect to the
reaction of NH4OH on Al Alloys that "ammonium hydroxide has a rapid initial reaction on aluminum alloys which decreases dramatically as pH and
concentration increase". Some reasons given relating to Al film formation.
For those rejecting a direct NH4OH and Al2O3 reaction, a conjecture is a possible reaction path with NH3 facilitating the creation of say, FeAl2O3
(or other impurity). See "Alumina as a textural promoter of iron synthetic ammonia catalysts" by H. Topsøe, J. A. Dumesic and M. Boudart. However,
reaction with Aluminum free of Fe impurity would nullify this hypothesis (which, by the way, I rate as unlikely).
[Edited on 21-6-2011 by AJKOER]
[Edited on 22-6-2011 by AJKOER]
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Neil
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| Quote: Originally posted by m1tanker78 |
Neil, it's worth mentioning that Al foil manufacturers usually coat the foil in a protective wax (or other similar substance). Other than that, I
don't have a good explanation of why your foil didn't produce any bubbles. My observations are identical to what AJOKER described in the OP. Try
tearing the foil into small pieces and look for bubbling at the edges.
Tank |
The wax is a very good point but I didn't observe any reaction with the "burnt" aluminum or the roughed aluminum until I added the salt. It looks like
the fractures in the "burnt" foil seem to produce the most bubbles.
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blogfast25
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| Quote: Originally posted by AJKOER | Actually, I find fascinating the tenacity of theorists!
I agree with the safety of Al container storage for NH3. However, this is not the case for NH3+H2O (I read on a NASA site once of a NH3/Al tubing
system that also mentioned in the event of moisture entering the system, a corrosive reaction could occur).
The sad truth is that anyone who ever has owned anything Aluminum knows (and a 2 minute internet search more than confirms) you cannot clean Aluminum
products with household ammonia (it causes pits).
As a chemist, you should know that this means that household ammonia (or its detergents? really) therefore dissolves/attacks the protective Al2O3
coating (or the 2% impurities which vary from Si, Fe, Mg and Mn?). This most likely means a chemical reaction given the resistance of protective
layer. One model (the least complex given the near entirely with which Al eventually dissolves) is the formation of an Aluminum ammonium complex that
exposes the underlying Al which readily reacts with H2O to produce H2 (Source: See "Concise Encyclopedia Chemistry" by deGruyter or search the web).
An undisclosed source on another forum states that the NH3 acts as a catalyst in the dissolving of Al with NH4OH with the release of H2 (which was
confirmed by the forum's author). I will see if I can obtain the actual source, but I am not expecting more than a casual reference.
I would advise you read the google book's entire section on Al2O3 and the other article that dates from 1940, good stuff!
[Edited on 21-6-2011 by AJKOER] |
AJKOER:
When in a hole stop digging.
You call me a ‘theorist’, yet you the ‘experimentalist’ have yet to provide the first shred of evidence for your wild theories, never mind the
ill digested sources which you keep rolling out, the latest one: ‘An undisclosed source on another forum states that the NH3 acts as a catalyst
in the dissolving of Al with NH4OH with the release of H2 (which was confirmed by the forum's author). I will see if I can obtain the actual source,
but I am not expecting more than a casual reference’.
This is also priceless: “One model (the least complex given the near entirely with which Al eventually dissolves) is the formation of an Aluminum
ammonium complex”.
So someone who is unable to prove what the observed gas really is now comes up with another corker: an ‘aluminium ammonia complex’. There is no
such thing but that never stops you, does it?
I could go on but I’ll limit myself to: ‘and what Neil said…’
You remind me of those ‘inventors’ of perpetual motion machines who say: “yeah, I know about the Second Law of Thermodynamics but I feel my
latest design will probably work anyway’.
[Edited on 21-6-2011 by blogfast25]
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AJKOER
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Hi:
Please see my revised note above that could support my argument that NH3 is dissolving the Al2O3 (although, to be fair, it is the added NH3 from the
AlN that is alluded to), or it is the chlorides and other components in the Salt Cake, in a higher pH environment, that are responsible. Interesting,
these are the two hypothesis currently on the table (a direct NH3 on Al2O3 path, or a corrosive Chloride activated reaction on the Al2O3, both in the
presence of an elevated pH.
I would like to amend my statement that the dissolving of Al2O3 in the presence of NH3 (one possible path), does not necessarily means the creation of
NH4[Al(OH)4], it may be that other unknown mechanisms are at work. I can also accept the Chloride activation path as the cause of the weakening of
the Al2O3 coat.
[Edited on 21-6-2011 by AJKOER]
[Edited on 22-6-2011 by AJKOER]
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Neil
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| Quote: Originally posted by AJKOER | I found an interesting reference on one of the slides titled "Presence of Aluminum Nitride in Salt Cake" presented by the Global Symposium on
Recycling, Waste Treatment and Clean Technology in Ocober 2008, Cancun, Mexico. In essence, the dissolving of AlN produces ammonia that raises the pH
which "dissolves the alumina film on unrecovered Aluminum particles surface, thereby exposing the Al surface to the reaction Al + H2O -->
Al(OH)3 + H2"
One could read this as the NH3 is reputedly directly dissolving the Al2O3 as the pH is raised.
Link: http://www.es.anl.gov/Energy_systems/docs/process_tech/indus...
As a sidebar, I also observed that leaving Al foil in vinegar for a few hours, even if apparently unreacted, does speed up the speed of the reaction
after the Al foil has been wash and placed into NH4OH. I got this trick from an Al Foil Coating manufacture article that lamented the power of acetic
acid to pierce through all their efforts to make the Al foil unreactive.
Here is the link on the NASA use of anhydrous NH3 with Al piping:
http://www.nasa.gov/offices/oce/llis/0698.html
Also from the cited reference: "Corrosion resistant materials handbook By D. J. De Renzo, Ibert Mellan", page 611, it appears with respect to the
reaction of NH4OH on Al Alloys that "ammonium hydroxide has a rapid initial reaction on aluminum alloys which decreases dramatically as pH and
concentration increase". Some reasons given relating to Al film formation.
For those rejecting a direct NH4OH and Al2O3 reaction, a conjecture is a possible reaction path with NH3 facilitating the creation of say, FeAl2O3
(or other impurity). See "Alumina as a textural promoter of iron synthetic ammonia catalysts" by H. Topsøe, J. A. Dumesic and M. Boudart. However,
reaction with Aluminum free of Fe impurity would nullify this hypothesis (which, by the way, I rate as unlikely).
[Edited on 21-6-2011 by AJKOER] |
| Quote: |
In essence, the dissolving of AlN produces ammonia that raises the pH which "dissolves the alumina film on unrecovered Aluminum particles surface,
thereby exposing the Al surface to the reaction Al + H2O --> Al(OH)3 + H2" One could read this as the NH3 is reputedly directly dissolving the
Al2O3 as the pH is raised. |
YES! EXACTLY! One could read it as that, if one wants to imagine chemical reactions, completely ignore the scientific process, misquote and
misrepresent a source and generally make up information to satisfy a theory which has no basis.
What it actually says is that the production of ammonia contributes to a rise in pH which aids in the digestion of aluminum still trapped in the
salt cake which was extracted from aluminum slag which is riddled with Chlorides.....
Here is the quote
| Quote: |
"Presence of aluminum nitride in salt cake
•
Reactivity with water
–
AlN + H2O Al2O3 + NH3
–
NH3 + H2O NH4OH (pH increases)
–
High pH dissolves alumina film on un-recovered aluminum particle surface
•
Exposes aluminum surface to reaction
–
Al + H2O Al(OH)3 + H2 (+ heat)
–
Hot H2 + O2 (air) + combustibles fire"
|
He is specifically talking about material which he described on the previous page:
| Quote: |
"Why recycle salt cake?
•
Recover residual aluminum (4-8%)
–
Economic and environmental benefit
–
Recover more that half of residual Al
•
>50% Al energy content (break-even at 2-3% Al)
•
Perceived environmental hazard related to salt cake composition
–
Reactive, pyrophoric
–
Noxious ammonia odor
–Leachable chloride content
" |
Bold added for emphasis.
 if your household ammonia sounds like the above mixture you may want to call
HazMAt and get a lawyer. Chlorides are long established as eating Al for breakfast - nothing in that presentation backs up anything you've claimed.
Suggesting that the author of the paper, who it seems is a noted expert on aluminum and magnesium chemistry, is saying that ammonia dissolves alumina
when he suggests no such thing is rather... bad form
| Quote: Originally posted by AJKOER | | Also from the cited reference: "Corrosion resistant materials handbook By D. J. De Renzo, Ibert Mellan", page 611, it appears with respect to the
reaction of NH4OH on Al Alloys that "ammonium hydroxide has a rapid initial reaction on aluminum alloys which decreases dramatically as pH and
concentration increase". Some reasons given relating to Al film formation. |
"decreases dramatically as pH and concentration increase"
From the NASA page you linked on heat exchangers, under a graph in which they delineate water and aluminum as being incompatible for the
purposes of aluminum heat exchangers is this sole mention:
"trace amounts of water in ammonia can lead to a reaction with the aluminum container and the formation of hydrogen gas."
Hey what is this? http://www.thescienceforum.com/viewtopic.php?t=16168&pos...
Relivance? You consider someone, who thinks dipping Al metal into "90% H2O, 10% NH3" creates AlN, as a credentialed source?
And this?
http://www.sciencemadness.org/talk/viewthread.php?action=pri...
| Quote: | | AJKOER here yet again. My personal observation is that freshly burned Al foil is more reactive than the original foil with respect to action by NH4OH.
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So burnt aluminum reacts better then unburnt aluminum?
Nope wait a sec
| Quote: | | Also, only the edges of torn foil are producing bubbles with NH4OH and after time, not all the foil is dissolving (some foil strips remain resistance
and are untouched). |
So freshly exposed aluminum which would likely have little oxide cover reacts faster, therefore alumina is dissolved by ammonia?
You change your story, forget data as it becomes evident that it contradicts you and ether intentionally or unintentionally misrepresent sources and
make spurious claims which are not only impossible but are down right ignorant and then you have the gall to patronize and insult others because you
are unwilling to admit you may be mistaken?
You've dug so deep you hit bull shit. You may find this helpful
http://www.envirochem.co.nz/pdfs/cowmate_techdata.pdf
Still interesting are the results m1tanker78 produced. The only aluminum I have access to is all alloyed, I'd like to know more and am trying to find
a source of low alloy Al to repeat your reaction.
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AJKOER
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Yes, upon re-reading the whole slide presentation, I independently revised my statement, because I wanted to be fair in the event someone else did not
pay attention to the other slides.
Sorry for the delay. I am basically in agreement with a two hypothesis scenario.
One of my problems is rejecting the observation that two different household ammonia actually do dissolve both Al and Al2O3. Neither of these NH4OH
solutions leave any salt residues! Please note that if you have read the tread, at least one other person has confirmed some of my observations and at
least one person has mentioned that the NH3 may be invading the porous Al2O3.
By the way, I noted that vinegar treated Al foil and Al2O3 both dissolved in NH4OH at about the same rate. This makes sense in that burning the Al
removes plastic coatings, oils and the annealing of the Al, all of which increases Al resistance to acids and the like.
[Edited on 22-6-2011 by AJKOER]
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Neil
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You can do this at home;
http://apps.caes.uga.edu/sbof/main/lessonPlan/BasicSynthesis...
This would also serve you well:
http://library.thinkquest.org/2923/tests.html
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AJKOER
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I think we close to a resolution.
First, here is an important reaction (I have performed it myself) that used in the mining of Copper ore:
CuO + 4 NH4OH -- Ammonium carbonate---> Cu(OH)2.(NH3)4 + 3 H2O
That is, the CuO is commercially successfully dissolved by aqueous ammonia in the presence of a weak acid or ammonium carbonate. Interestingly,
Concise Encyclopedia Chemistry by DeGruyter notes that (NH4)2CO3 solution dissolves CuO.
Second, assume we have a general consensus that Al2O3 and NH4OH dissolve in the presence of a NaCl or KCl (we have a reference and direct observations
on this).
So per our Copper ore example, what compound would you think is produced from the reaction of Al2O3 in excess NH4OH in the presence of NaCl?
[Edited on 22-6-2011 by AJKOER]
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Fleaker
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What reaction?
Al2O3 has different modifications. Some are easier to digest than others. Ammonia won't do the job well at all.
Neither flask nor beaker.
"Kid, you don't even know just what you don't know. "
--The Dark Lord Sauron
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AJKOER
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The Al203/AlN/Al prepared from burning Al with traces of Si and Fe, for example.
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blogfast25
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Neil:
Excellent debunking but you won’t really catch AJKOER: he moves the goal posts al the time. Take this for example:
“Please note that if you have read the tread, at least one other person has confirmed some of my observations and at least one person has
mentioned that the NH3 may be invading the porous Al2O3.”
Regards the latter part of that statement, it was Tank who correctly pointed to diffusion of NH3 through the Al2O3 based passivation layer. That is
indeed very likely to be the case. Take titanium for example: like Al it passivates to a TiO2 layer of only a few atoms thick. TiO2 is COMPLETELY
insoluble in HCl, no matter how concentrated or hot (with the exception of very freshly prepared Ti(OH)4), yet hot, strong HCl attacks titanium metal
readily, so vigorously that the acid is used to make Ti<sup>3+</sup> solutions (I’ve done this many times). Obviously the acid (like NH3
a small molecule) can penetrate the oxide layer w/o actually dissolving it.
Yet the partial acceptance of Tank’s claim is now presented as if it confirms the reaction between “NH4OH” (sic) and alumina.
With regards to the dissolution of Al2O3, I suggest AJKOER reacts some Al powder with KClO3: 2 Al + KClO3 === > Al2O3 + KCl. This runs so hot you
obtain annealed alumina (the KCl get blown off because the temperature exceeds its boiling point). I suggest he then tries to dissolve the
alumina in the alkali of his choice: whether “NH4OH”, NaOH or KOH. Alternatively look up ‘Bayer process dissolution Bauxite’ to grasp just how
difficult the digestion of alumina with strong alkalis really is. It might just about shut him up about “NH4OH” in this context.
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AJKOER
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Thanks for the interesting points blogfast25, but the question does not relate to the dissolving of Alumina by NH4OH at this time, but Alumina + Salt
+ NH4OH, with the clear understanding that it is the burnt Al contaminated with AlN and Al (that is, the one we have been experimenting with) in play.
Also, there is no time limit on this game (forgive the sport analogy, but blogfast25 started it), so a boring game (you may have seen one) with a
point on the scoreboard taking forever (meaning that no one would be likely to sell this game commercially) still counts.
Still waiting for an answer.
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blogfast25
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To what question? You’ve changed the story that many times hardly anyone here still knows what you’re talking about! It’s certainly been quite
an arc: from alumina cracking NH3 into nitrogen and hydrogen to mixtures of Al2O3 and AlN giving rise to NH3 and the latter assisting in the
dissolution of residual Al.
So when, instead of trying to unsuccessfully dodge every bullet, will you present some actual observations, followed up perhaps with some real
evidence for what you observed, huh? How about that?
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m1tanker78
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| Quote: Originally posted by blogfast25 | [...]present some actual observations, followed up perhaps with some real
evidence for what you observed, huh? How about that?
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I agree. AJOKER, what is it you're after? I second Blog's suggestion to look into the Bayer Process. Set up some meaningful experiments and get some
rewarding 'hands-on' time. As you can see, it's a tough crowd!  I, myself,
learned that the hard way with some sloppy experiments and bad assumptions.
Tank
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LanthanumK
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Aluminium is still a metal; although its oxide is amphoteric it does not have the acidic character of a nonmetal oxide such as sulfur trioxide.
Ammonia is a weak base, not a strong base. There is a difference between a strong and a weak base. Ammonia is not basic enough to dissolve Al2O3.
Copper oxide forms an ammine complex with NH3 ions. I don't know if this has been brought up before, but here is a thread about aluminium ammine ions:
http://www.sciencemadness.org/talk/viewthread.php?tid=10977. Is this what you mean when you are referring to aluminium ammonia complexes?
hibernating...
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PHILOU Zrealone
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Maybe this observation will help?
Al does dissolve into NH4NO3.
Normally Al is said to be resistant to concentrated HNO3 and I wanted to test if I could make some Al(NO3)3 or a Al(NO3)3.xNH3 complex from Al and
NH4NO3 solution... so I have put some Al foil into a glass jarr with a plastic screewcap and some concentrated NH4NO3 water solution.
At normal ambiant temperature nothing seemed to happen for days...
But about a few weeks later I thought back to that forgotten experiment bottle...and all the silvery Aluminium metal had dissappeared into a fine
white mud...the cap was deformed and had tiny cracks on the side...I unscreewed the cap to allow somme gas to come out.
To my understanding ammonium/ammonia salts eather:
1°)Free some ammonia that allow partial or total dissolution of the Aluminium oxyd/hydroxyd layer in a reversible fashion.
2°)Make a soluble complex of the type NH4Al(OH)3(NO3)
3°)Make a transient (NH4)3AlO3 aluminate
The process seems slow but naked Al is produced because of gas generation and silvery foil dissappearing.
Al + 3H2O --> Al(OH)3 + 3/2 H2
I'm quite sure that NH4Cl will do even better (see my answer in the other tread on Cu(2+) and Al).
Reaction of NH4Cl + CuSO4 + Al must be even faster than with NaCl + CuSO4 + Al.
To add to the joy of the mix NH3 will complexate some Cu(2+) and CuO protective layer
and dissolve (with help of oxygen from the air) the just precipitated Cu powder.
PH Z (PHILOU Zrealone)
"Physic is all what never works; Chemistry is all what stinks and explodes!"-"Life that deadly disease, sexually transmitted."(W.Allen)
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AJKOER
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With respect to "sloppy" experiments, I am not alluding to any of my work here, but to others in this thread using pure ingredients, better lab
equipment and undoubtedly more seasoned lab procedures (thanks for the educational threads, I am sure many may benefit from them). Also, it was not
also my suggested route of using KCl as a reaction catalyst for Alumina and NH4OH, so any criticism of "my" reaction or "my" sloppiness are not
relevant.
The question has already been very clearly presented. If you have issues with the possible answer, or just don't know, please do not respond. I would
respectfully ask you to display courtesy in allowing new or existing participants to contribute.
After receiving replies, I will revise my current views, or may just present the consensus view, and post to allow for final comments. Note,
non-responses (including requests for time-outs, instant replays and/or attacks on the referee) will not contribute to the consensus view (or modify
mine).
I sincerely wish to thank those who expended their time and lab resources to add to this tread.
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AJKOER
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PH Z (PHILOU Zrealone)
Thanks for prior experimental results that interestingly mirror my cited CuO + NH4OH which also proceeds in the presence of dilute acids (think HNO3)
as I noted.
In the current case, think of Al2O3 + NH4OH ----in dilute HNO3-->
I like all of your answers, and I believed (despite some claims of my sloppiness), have witness the reversibility phenomena.
Thanks again.
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Neil
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| Quote: Originally posted by AJKOER | With respect to "sloppy" experiments, I am not alluding to any of my work here, but to others in this thread using pure ingredients, better lab
equipment and undoubtedly more seasoned lab procedures (thanks for the educational threads, I am sure many may benefit from them). Also, it was not
also my suggested route of using KCl as a reaction catalyst for Alumina and NH4OH, so any criticism of "my" reaction or "my" sloppiness are not
relevant.
The question has already been very clearly presented. If you have issues with the possible answer, or just don't know, please do not respond. I
would respectfully ask you to display courtesy in allowing new or existing participants to contribute.
After receiving replies, I will revise my current views, or may just present the consensus view, and post to allow for final comments. Note,
non-responses (including requests for time-outs, instant replays and/or attacks on the referee) will not contribute to the consensus view (or modify
mine).
I sincerely wish to thank those who expended their time and lab resources to add to this tread.
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Thank you Gert.
AJKOER
Please do not suggest that I used KCl in an attempt to dissolve Alumina, I did no such thing. The problem is not that you are theorizing or attempting
to further your understanding it is that you are making fallacious claims.
There are no scores in science, because ultimately there is only reality. Chemistry is nothing more or less then the study of the material which makes
up your reality, matter. Scientist who decide there is a score cease being scientists in the same moment, for example Dr. Hwang Woo-Suk.
Contribution implies offering information, quid pro quo, ideally.
Do you have HCl, the ability to get red cabbage, Al foil, NaCl, household ammonia and distilled water?
What glassware do you have access to? Do you have a scale? Do you want a answer that you can verify on your own?
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m1tanker78
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ajoker: get it together! Go back and read my post a little more carefully. Now, tell me who I accused of performing sloppy experiments. I'll be
damned, I incriminated... myself.
For the record (and without double meanings, score keeping or any BS), I will say that you should perform and VERIFY some of YOUR OWN
experiments when a theory flies into your head or when you read something that interests you. Feedback is good but don't expect everyone to drop what
they're doing so they can pull the weight...
Tank
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AJKOER
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Neil:
Points well taken.
However, should I refer to the use of a catalyst (KCl) in the reaction of NH4OH on Alumina as your "reaction"?
Or, joint ownership? Or, product of thread participants work?
Or if you wish, I will, by default, assume full responsibility for it as I am aware of the Ammonium carbonate catalyst in the dissolving copper ore,
and my dated reference does note the significance of dilute NH4Cl on Al(OH)3 precipitation, so I am comfortable with the concept.
Your choice, I would not want to ascribe any research to you without your consent if it was unintentional on your part.
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Neil
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"What color is the house on that hill?"
"Yellow!"
No!
"It appears yellow on this side!"
Yes!
Do you see the difference? In one instance I make an assumption, in the other I make an observation.
I observed nothing which suggests a reaction along the lines you are attributing.
I knew from experience that CuSO4 and Al react in water but need a Cl- source, normally I use NaCl.
Based on this knowledge I added a Cl- source. Why did I use KCl? Because I had no NaCl at hand.
What did I observe? A reaction occurred which produces a gas.
So to re-phrase:
The reason I added the Cl- source was because I hypothesized that it would allow the aluminum to react in a manner similar to the observations you
described and that Cl- contamination in household ammonia was a not unlikely possibility.
What did I learn and observe?
The gas tested positive as being at least partially hydrogen. It tested negative for being ammonia. To be very fair, it tested positive for being a
buoyant flammable gas. The KCl did in fact seem to trigger a reaction.
Did the KCl trigger the reaction? I do not know that for certain. The KCl came from NoSalt which contains anti caking agents which include tartrates
and silicates IIRC. Could they have been responsible? Strictly speaking - I do not know.
If you wish to form a hypothesis that the observed reaction involved the Al2O3, which we assume to be present, then you need to find a way to measure
any changes to the Al2O3 skin.
What about AlN? Do we know there is any present? Do we know if it is statistically significant? Do we know if it's formation is even plausible?
There are two sides to the scientific method. One is that it produces research which can be referred to and the other is that it can keep you alive.
For example, the post by AquaRegia where he detailed a very devastating event which occurred because he made a single assumption. You can never
assume. In chemistry assuming doesn't just make an ass out of U it can also make you bleed or die.
I bring this up because based on other threads where you have posted it seems you have an interest in energetics. Based on what you've said and done
in this thread, I strongly suggest you put in some textbook time. If you want to learn chemistry you have to be willing to trash a theory when it is
undercut and you have to be open to being 100% wrong, otherwise you will end up being ether 100% ignored or worse, 100% dead.
If you wish to stop assuming, then start testing out what you suspect in a safe and scientific manner. If not, I suggest you take up Magic cards.
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