Question

Consider the following compounds
1. $(NH_4)_2Cr_2O_7$
2. $NH_4NO_2$
3. $NH_4 VO_3$
4. $NH_4 NO_3$
Which compound(s) yield nitrogen gas upon heating?

• A. 1 and 2
• B. 2 and 3
• C. 3 and 4
• D. 1 and 4
• E. All

Answer 1

Answer: (A)

Only $\left( NH _{4}\right)_{2} Cr _{2} O _{7}$ and $NH _{4} NO _{2}$ give $N _{2}$ on
heating.
(i) $\left( NH _{4}\right)_{2} Cr _{2} O _{7} \xrightarrow{\Delta} Cr _{2} O _{3}+4 H _{2} O + N _{2}$
(ii) $NH_4NO_2 \xrightarrow[\Delta]{\text{Thermal decomposition}} 2 H_2O +N_2$