Chemical Forums
Specialty Chemistry Forums => Citizen Chemist => Topic started by: Sophia7X on November 08, 2012, 10:13:00 PM
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I was making H2 gas in a flask with a stopper and tubing connected to a balloon. I used HCl and Al, when the reaction proceeded, the mixture was grey. Then the next day, it was a clear, bright yellow. I left the stopper on... wondering what could have caused this?
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From WIKI
Aluminium chloride (AlCl3)
Appearance white or pale yellow solid, hygroscopic
It is white, but samples are often contaminated with iron trichloride, giving it a yellow colour.
My Side Comments
Remember that you initially had AL, HCl, some Air, Water (can we assume pure) in your flask.
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This really depends on how pure you aluminum was. If you bought pellets from a chemical supplier, fine. But if you wadded up household aluminum foil (this post is in Citizen chemist,) then the aluminum is very impure. Also, I'd notice, when I was playing with muriatic acid that I'd purchased from the hardware store, that it is likewise impure, and yellows on exposure to air.
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Stopper would be my first guess.
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Not sure about the aluminum being the reason since it took a while for the color to change to yellow... maybe it was the HCl.
How would a stopper turn something yellow?
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Something could be leached out of the material.
Unless it was a glass stopper.