Sciencemadness Discussion Board

Li2CO3 + Mg metal blows content out of retort

metalresearcher - 28-9-2011 at 11:30

Trying to make Li metal after Na (succesful) and K (not yet succesful) I put Mg drillings and Lithium carbonate (from aceramics shop) in a steel tube and heated it and then it nearle exploded out of the tube. Very spectacular but no Li metal yet....
I have to redesign te retort ...

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barley81 - 28-9-2011 at 12:27

Maybe using lithium hydroxide instead of lithium carbonate would make the reaction a bit more calm. Also, I'm not sure that lithium can be made from Mg because lithium is a stronger reductor than Na or K. Just speculating...
Wikipedia says that lithium hydroxide can be made by reacting (maybe boiling for a long time) hydrated lime and lithium carbonate. The filtered solution can be evaporated to give the monohydrate, which can be dehydrated at 180C (also from Wikipedia). The materials are very cheap.
Awesome flare, I like that the blowtorch flame turned red from the lithium after the reaction.

Off topic: I am now a hazard to others!

AndersHoveland - 28-9-2011 at 12:46

Probably stating the obvious, but the reaction is probably something like:

Li2CO3 + (2)Mg --> Li2O + (2)MgO + C

where the carbon could also be in the form of carbon monoxide or magnesium sesquicarbide (Mg2C3), depending on the ratio of magnesium used.

As you no doubt already know, both magnesium and lithium can burn in nitrogen or carbon dioxide. Potassium and sodium, however, can only burn in carbon dioxide, not nitrogen. Despite being more "reactive" metals, the nitrides of sodium and potassium are surprisingly unstable. This is likely due to both crystal lattice energies (+1 and -3 ions are not held together as strongly) and the much more ionic character of the bonding, since it is less favorable for 3 extra electrons to occupy the relatively small atomic orbital in a nitrogen atom. The bonding character of Li-N, Mg-N, and Ca-N bonds is more covalent.

BromicAcid - 28-9-2011 at 15:00

Research before you experiment!

http://www.sciencemadness.org/talk/viewthread.php?tid=1974

As with most everything here, we're still doing chemistry from 50-100 years ago and in essence 'it's all been done', we're just re-discovering things.

Quote:
Reduction of LiOH or Li2CO3 or LiCl with magnesium as stated in Complete Treatise on Inorganic Chemistry is explosive but 40% magnesium oxide can be added to moderate the reaction.


Sometimes it can take awhile to find what you're looking for, but what's the quote... ten minutes in the library can save ten hours in the lab? (or something like that) Or better yet it can save a trip to the hospital.

metalresearcher - 29-9-2011 at 09:15

Before trying it, I filled in the parameters in this site:

http://www.crct.polymtl.ca/equiweb.php

2Li2CO3 + 6Mg -> 6MgO + Li2C2 + 2Li

That is why I expected Li metal.....