Sciencemadness Discussion Board

Lithium and nitrogen

vmelkon - 4-8-2012 at 04:40

Simple question :
According to http://en.wikipedia.org/wiki/Lithium
Lithium is the only metal which reacts with nitrogen under normal conditions.

So, it can't be stored in pure N2 otherwise it forms a layer on nitride on its own?

Kalium - 4-8-2012 at 05:14

"Crystalline lithium nitride, stable in air, characterized by a sodium content of less than 5×10^-2 weight-percent, a potassium content of less than 10^-2 weight-percent, a magnesium content of less than 1×10^-2 weight-percent, and a silicon and iron content of 10^-2 to 10^-3 weight-percent each; is obtained by heating lithium having a purity of at least 99.9% in a vessel made of tungsten, niobium, ruthenium or tantalum in a nitrogen atmosphere at a pressure of at least 250 mm Hg in the absence of oxygen and water at a temperature of from 300° C. to the melting point of lithium nitride."
Under room temperature, I think only a negligible amount of lithium nitride will form.

Nicodem - 4-8-2012 at 10:34

It can be stored under nitrogen, but such storage is of no use, because the nitrogen will react with lithium in few days. You need to use argon if you want it clean from the nitride and oxides.

vmelkon - 4-8-2012 at 11:12

Quote: Originally posted by Nicodem  
It can be stored under nitrogen, but such storage is of no use, because the nitrogen will react with lithium in few days. You need to use argon if you want it clean from the nitride and oxides.


Thanks.

Vargouille - 4-8-2012 at 11:18

There's a video where a piece of cut lithium begins to darken fairly quickly from reaction with nitrogen.

[Edited on 4-8-2012 by Vargouille]

vmelkon - 5-8-2012 at 04:26

That is odd. I assume it forms a mixture of oxide (white) and nitride (red purple?).
According to wikipedia, the nitride is red purple but on the video, it seems brown.