Pyro - 12-5-2012 at 09:17
hi,
i recently bought some magnesium ribbon from ebay, it said 99.9% Mg, but when i lit a piece it didnt burn nearly as bright as i remember, and can be
extingiushed with water.
does anybody have any idea how i would find out how pure this is without using archimedes' way with volume and weight? besause i really dont feel like
getting my roll wet, and i don't have scales accurate enough for this.
thanks,
alex
99chemicals - 12-5-2012 at 10:20
There are two ways main ways to make magnesium metal commecialy.
1)Electolosis of molten magnesium chloride. If that is the method is used the primary contaminents would probably be magnesium oxide and carbon.
2)The chinese method. This is called the Pidgeon process. It is a silicothermic reaction where the magnesium is reduced from magnesium oxide via
silicon metal. This reaction is not very thermodynamicly favorable so the eqalibrium can be pushed to the right by removing some of the products. The
magnesium is distilled of and collected. This reaction is preformed a very high temperature. The contaminints here would probably be magnesium oxide
or calcium metal.
The problem with finding the contaminets that would be only .1% of the total mass which would be very difficult to isolate. If I was you I would just
use the magnesium as is and not test it.
If you were to test you should dissolve 5g of the Mg in very dilute HCl. Then if there is any insoluble matter left it will probably be carbon. Then
add some some sodium sulfate. Then wait over night. If there is any insoluble matter then there would have been calcium contamination in the
magnesium.
Sourced from Wikipedia on the Magnesium page and the article on the Pidgeon Process.
[Edited on 5-13-2012 by 99chemicals]
Pyro - 12-5-2012 at 11:04
thanks, ill try it.
but if there is Ca in it should burn well, no?
ill let you know what happens.
thanks.