Decomposition of LiNO3

Question

I have a doubt about decomposition of alkali metals. Why does $\ce{LiNO3}$ decompose to give $\ce{Li2O}$ and $\ce{NO2}$ where as other alkali metals decompose to give corresponding nitrite and oxygen?

Answer 1

Have you checked Wikipedia?

Upon thermal decomposition, $\ce{LiNO3}$ gives lithium oxide ($\ce{Li2O}$), nitrogen dioxide, and oxygen:

$$\ce{4 LiNO3 → 2 Li2O + 4 NO2 + O2}$$

Other group I nitrates decompose differently, forming the nitrite salt and oxygen. Because of its relatively small size, the lithium cation is very polarizing, which favors the formation of the oxide.

Answer 2

You actually can get lithium nitrite from the nitrate by controlling the decomposition temperature around 500°C. But yes, as Nilay points out the nitrite is more prone to decomposing further than sodium nitrite because of the polarizing power of the lithium cation.