Qualitative Analysis - Result Question 59
####62. A colourless inorganic salt $(A)$ decomposes completely at about $250^{\circ} C$ to give only two products $(B)$ and $(C)$, leaving no residue. The oxide $(C)$ is a liquid at room temperature and neutral to moist litmus paper, while the gas $(B)$ is a neutral oxide.
White phosphorus burns in excess of $(B)$ to produce a strong white dehydrating agent. Write balanced equations for the reactions involved in the above process.
(1996, 3M)
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Solution:
$$ \underset{\text { Inorganic salt }}{A} \stackrel{250^{\circ} C}{\longrightarrow} \underset{\begin{array}{c} \text { Neutral } \\ \text { oxide } \end{array}}{B}+\underset{\begin{array}{c} \text { Neutral oxide } \\ \text { (liquid) } \end{array}}{C} $$
Oxide $C$ is liquid and neutral to litmus, so it is $H _2 O$. White phosphorus burns in excess of $B$ to give $P _4 O _{10}$.
Therefore, $B$ is $N _2 O$.
$$ \begin{gathered} NH _4 NO _3(A) \stackrel{\Delta}{\longrightarrow} N _2 O+2 H _2 O(l) \\ P _4+10 N _2 O \longrightarrow P _4 O _{10}+10 N _2 \end{gathered} $$
