Sciencemadness Discussion Board
Not logged in [Login ]
Go To Bottom

Printable Version  
 Pages:  1  ..  3    5
Author: Subject: Isolation of Boron from Borax (Sodium Tetraborate)
elementcollector1
International Hazard
*****




Posts: 2684
Registered: 28-12-2011
Location: The Known Universe
Member Is Offline

Mood: Molten

[*] posted on 7-1-2014 at 14:40


Quote: Originally posted by eidolonicaurum  


Having tried to do this myself, it is almost impossible to light an aluminium/boric oxide mixture easily. I gave up on aluminium and used magnesium instead. It worked that time. I then chucked the products into dilute acid, which dissolves away everything except the boron. I got an amorphous brown powder.

Curious... I watched MrHomeScientist's video and he obtained the black, crystalline allotrope. There is an amorphous brown allotrope, but it is not stated how this is prepared as opposed to the crystalline black.
Assuming the above is amorphous boron, what gave rise to the different allotropy?




Elements Collected:52/87
Latest Acquired: Cl
Next in Line: Nd
View user's profile View All Posts By User
blogfast25
Thought-provoking Teacher
*****




Posts: 10464
Registered: 3-2-2008
Location: Neverland
Member Is Offline

Mood: No Mood

[*] posted on 8-1-2014 at 06:32


Quote: Originally posted by elementcollector1  
Curious... I watched MrHomeScientist's video and he obtained the black, crystalline allotrope. There is an amorphous brown allotrope, but it is not stated how this is prepared as opposed to the crystalline black.
Assuming the above is amorphous boron, what gave rise to the different allotropy?


To get a crystalline product the melting point of the boron must at least be reached (that is a necessary but not necessarily sufficient condition). So perhaps it was just a question of end-temperature of the reaction.

What makes you conclude his product was crystalline though? The naked eye does not do XRD very well! ;)




View user's profile View All Posts By User
mkurek
Harmless
*




Posts: 8
Registered: 23-12-2013
Member Is Offline

Mood: No Mood

[*] posted on 8-1-2014 at 08:25


Quote: Originally posted by bismuthate  
i have a idea! i can put the crucible of borax on a Al/MnO2 thermite mixture which will run for quite a while. will that work?


Definitely would not do that with thermite.




View user's profile Visit user's homepage View All Posts By User
blogfast25
Thought-provoking Teacher
*****




Posts: 10464
Registered: 3-2-2008
Location: Neverland
Member Is Offline

Mood: No Mood

[*] posted on 8-1-2014 at 09:05


Quote: Originally posted by mkurek  

Definitely would not do that with thermite.


Definitely not with MnO2 thermite.

With other thermites it becomes a question of heat transfer from the thermite to the boron reaction and of what kind of crucible could withstand such a thermal shock.




View user's profile View All Posts By User
 Pages:  1  ..  3    5

  Go To Top