Chemical Forums

Chemistry Forums for Students => Inorganic Chemistry Forum => Topic started by: quantboy on September 14, 2013, 12:31:08 PM

Title: Gallium - unexplained state change
Post by: quantboy on September 14, 2013, 12:31:08 PM

I purchased 20g of Gallium (99.9% purity).  After demonstrating it's unique properties of being solid at room temperature, and melting at body temperature several times, the sample started to collect some "lint" or other solid debris that didn't melt at elevated temperatures (90-120F).  I had the bright idea to take a clean beaker, put the gallium in the bottom of the beaker, and run how tap water into the center of the gallium.  The gallium being heaver stayed in the bottom, debris was able to be scooped out with a pipette, and the water then dumped off.

The problem is now the gallium wont change back to a solid even at 50F!  Can anyone explain what might have happened?  How can I re-purify my sample?

Thanks in advance for any advice/thoughts.

Title: Re: Gallium - unexplained state change
Post by: magician4 on September 16, 2013, 08:30:32 AM

my best guess is:

gallium tends to need some initial crystalls (or even rough surfaces, impurities) before solidifying, else it might take a lot of time / significant more cooling to solidify

 :rarrow: put it in a fridge and wait some days: it might have become "too clean" by your purification, and now needs to take it's time

regards

Ingo

Title: Re: Gallium - unexplained state change
Post by: codairem on September 27, 2013, 10:09:50 PM

Another possibility is that there were metallic impurities (e.g., Al dust) among the debris that didn't float but instead amalgamated with the Ga, thus depressing its melting point.  In any case refrigerating it to 0C or so should do the trick. 

Please let us know the result!