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Specialty Chemistry Forums => Citizen Chemist => Topic started by: Sophia7X on November 08, 2012, 10:13:00 PM

Title: Yellow solution?
Post by: Sophia7X on November 08, 2012, 10:13:00 PM

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?

Title: Re: Yellow solution?
Post by: billnotgatez on November 09, 2012, 05:27:23 AM

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.

Title: Re: Yellow solution?
Post by: Arkcon on November 09, 2012, 06:45:30 AM

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.

Title: Re: Yellow solution?
Post by: Borek on November 09, 2012, 12:04:12 PM

Stopper would be my first guess.

Title: Re: Yellow solution?
Post by: Sophia7X on November 09, 2012, 04:44:41 PM

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?

Title: Re: Yellow solution?
Post by: Borek on November 09, 2012, 05:35:11 PM

Something could be leached out of the material.

Unless it was a glass stopper.