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Topic: Aluminum Precipitation  (Read 5114 times)

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Offline angeloposteraro

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Aluminum Precipitation
« on: June 18, 2010, 02:49:40 AM »
Hello all,

I was wondering if it is possible to make an HCl solution and react aluminum (either from foil or the lab) and then after neutralizing the solution add magnesium flake in order to precipitate the aluminum.

Secondly I was wondering what would best neutralize the acid before the magnesium, would sodium bicarbonate be best? It was my first choice as the sodium salts formed would not be displaced with the magnesium.

the end result of course being precipitated aluminum powder in very fine particles.

This powder would be mixed with varying levels of oxidizers, KNO3, KClO4, etc to show the 12th grade class I teach the effects of powerful oxidizers, and to finish our unit on the chemistry of fireworks.

Offline Donaldson Tan

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Re: Aluminum Precipitation
« Reply #1 on: June 19, 2010, 01:53:20 AM »
Doesn't sound like a good idea considering the safety aspect of adding Magnesium to water.
"Say you're in a [chemical] plant and there's a snake on the floor. What are you going to do? Call a consultant? Get a meeting together to talk about which color is the snake? Employees should do one thing: walk over there and you step on the friggin� snake." - Jean-Pierre Garnier, CEO of Glaxosmithkline, June 2006

Offline angeloposteraro

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Re: Aluminum Precipitation
« Reply #2 on: June 20, 2010, 04:27:31 AM »
     Magnesium hardly reacts with water at any reasonable temperature, also, adding aluminum to Hydrochloric acid is much more vigorous.

     I tried this reaction and the main problem I have is neutralizing the solution so that the Magnesium will displace the aluminum and merely react with the acid

So, what combination of aluminum salt and neutralizer should I use for ease and efficiency ? I have contemplated drying the AlCl3 mixture and re-adding it to water thereby driving off the HCl bu this would waste a lot of time.

Offline tamim83

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Re: Aluminum Precipitation
« Reply #3 on: June 20, 2010, 10:48:29 PM »
How much Al powder do you intend to make?  It seems like you can use some stoichiometry to figure this out.  You may need to either use the stoichiometric equivalent or a slight excess of HCl solution.  In this way there is less HCl to react with the neutralizer and you will know exactly how much sodium bicarbonate to add to completely neutralize the acid.  On top of the calculations, I would test the pH of the solution after adding the sodium bicarbonate to be sure it is neutral. 

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