Question

The products obtained when lithium burns in air are:

• A. $L{i}_{2}O,L{i}_2{O}_2$
• B. $L{i}_{2}O,L{i}_{3}N$
• C. $L{i}_{2}O$ only
• D. $L{i}_{3}N$ only

Answer 1

The correct option is B $L{i}_{2}O,L{i}_{3}N$

Lithium metal is quite easily cut with a knife. The result is a shiny silvery surface but this soon tarnishes because of reaction with oxygen and moisture from the air. When lithium is burned in air, the main product is the white oxide lithium oxide, Li${}_2$O.

4Li(s) + O${}_2$(g) → 2Li${}_2$O(s)

Lithium also reacts with nitrogen, N${}_2$, to form lithium nitride, Li${}_3$N. None of the other Gruop 1 elements do anything similar, but magnesium (Gruop 2) similarly forms a nitride.

6Li(s) + N${}_2$(g) → 2Li${}_3$N(s)

Hence, the correct option is $\text{B}$