Question

What is the formula of lithium imide?

• A. $\mathrm{LiNO_3}$
• B. $\mathrm{Li_2NH}$
• C. $\mathrm{Li_3N}$
• D. $\mathrm{LiNH_2}$

Hint:

Imides contain the $\mathrm{NH^{2-}}$ ion, while amides contain the $\mathrm{NH_2^-}$ ion.

Answer 1

The Correct Option is B

Step 1: Understanding imide ion.
Imide ion has the formula $\mathrm{NH^{2-}}$. It contains nitrogen bonded to one hydrogen atom with a charge of $-2$.

Step 2: Charge balance with lithium.
Lithium forms $\mathrm{Li^+}$ ions. Two lithium ions are required to balance the $-2$ charge of the imide ion.

Step 3: Formation of lithium imide.
Combining two $\mathrm{Li^+}$ ions with one $\mathrm{NH^{2-}}$ ion gives the formula $\mathrm{Li_2NH}$.

Step 4: Conclusion.
Hence, the correct formula of lithium imide is $\mathrm{Li_2NH$}.