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Topic: Identification of aluminum mixture  (Read 2574 times)

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Offline kamikaze762x39

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Identification of aluminum mixture
« on: February 06, 2017, 08:40:25 PM »
I'm posting in the off chance that someone might know how to identify a mixture I made.  I searched to see what I ended up with and got as far as finding out that my initial reaction probably yielded aluminum chloride or hydroxide.  Beyond that, I am not sure.

I reacted aluminum metal (cans) with 20 baume hydrochloric acid (muriatic acid) in a stainless steel pot.  The compound, as expected, yielded a greyish pasty material I intended to boil this off and continue heating the compound to convert it to mostly oxides for a refractory material. 

I had the idea of adding some hydrogen peroxide just to see what it would produce, if anything, and I was very surprised at the results.  First off, it reacts immediately, giving off what I believe to be hydrogen and oxygen gases (it pops violently when exposed to flame).  At first I considered that the peroxide might simply be undergoing a decomposition reaction, but I also got a significant color change.  It turns immediately from greyish to extreme yellow.  After the reaction completes and it is allowed to settle, it separates into two layers, as pictured.  I believe the bottom layer might be mostly aluminum hydroxide, but I cannot even begin to guess what the top layer could be.  It is extremely brown, clear, non-flammable (as expected), thin as water, and mostly odorless.  Anyone have any idea what it could be?

Edit:  I also just discovered that it is immiscible with water, which really blows my mind.  The water forms a third layer atop the mystery material.  It may not be entirely immiscible as I have not tried to force it to mix, but it definitely does not mix easily.

« Last Edit: February 06, 2017, 08:55:51 PM by kamikaze762x39 »

Offline Hunter2

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Re: Identification of aluminum mixture
« Reply #1 on: February 07, 2017, 12:54:44 AM »
If you put hydrochloric in a stainless steel pot it will dissolve the metal also, beside your aluminium what cause colourless compounds you can find yellow to brown iron compounds. You add hydrogen peroxide what accelerates the reaction and get free chlorine what attacks more stronger.

Offline Arkcon

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Re: Identification of aluminum mixture
« Reply #2 on: February 07, 2017, 05:43:25 AM »
I used to play with HCl and aluminum too, and its hard to know what you get from the usual online resources.  ?However, ikts a pretty common experiment, and often mentioned on this board, for example: http://www.chemicalforums.com/index.php?topic=80732.msg294007#msg294007
Hey, I'm not judging.  I just like to shoot straight.  I'm a man of science.

Offline kamikaze762x39

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Re: Identification of aluminum mixture
« Reply #3 on: February 08, 2017, 07:00:07 PM »
Thanks for the responses.  Based on what I could tell from the other forum link, I most likely have a contaminated aqueous solution of aluminum chloride on top with aluminum hydroxide settling at the bottom.  Fascinating.

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