Question

Which metal nitrate would give the respective metal, $N{{O}_{2}}$ and ${{O}_{2}}$ on heating?
A. $AgN{{O}_{3}}$
B. $Cu{{\left( N{{O}_{3}} \right)}_{2}}$
C. $Pb{{\left( N{{O}_{3}} \right)}_{2}}$
D. $KN{{O}_{3}}$

Answer 1

Hint: The metal combines with nitrate and forms metal nitrates. All the metal nitrates won’t produce respective metal $N{{O}_{2}}$ and ${{O}_{2}}$ on heating. Few metal nitrates undergo decomposition on heating and form metal oxide, $N{{O}_{2}}$ and ${{O}_{2}}$ as the products.

Complete step by step answer:
- In the question it is given which metal nitrate gives a respective metal, $N{{O}_{2}}$ and ${{O}_{2}}$ on heating among the given options.
- All group-1A metal nitrates except lithium nitrate gives metal nitrite and oxygen on heating.
- Among the given options, Option D. Potassium nitrate belongs to group-1A nitrates.
- Potassium nitrate on heating decomposes and forms potassium nitrite and oxygen as the products.
- The decomposition of potassium nitrite is as follows.
\[KN{{O}_{3}}\xrightarrow{\Delta }KN{{O}_{2}}+\frac{1}{2}{{O}_{2}}\]
- All divalent metal nitrates expect mercury nitrate to decompose and form respective metal oxide, $N{{O}_{2}}$ and ${{O}_{2}}$ on heating.
- Among the given options, option B and C. Copper nitrate and lead nitrate are bivalent nitrates decomposes and forms respective metal oxides, $N{{O}_{2}}$ and ${{O}_{2}}$ on heating.
- The decomposition of divalent metal nitrates is as follows.
\[\begin{align}
  & Cu{{(N{{O}_{3}})}_{2}}\xrightarrow{\Delta }CuO+N{{O}_{2}}+{{O}_{2}} \\
 & Pb{{(N{{O}_{3}})}_{2}}\xrightarrow{\Delta }PbO+N{{O}_{2}}+{{O}_{2}} \\
\end{align}\]
- The monovalent metal nitrates decomposes and produces respective metal $N{{O}_{2}}$ and ${{O}_{2}}$ on heating.
- Among the given options, option A. Silver nitrate decomposes and forms respective metal, $N{{O}_{2}}$ and ${{O}_{2}}$ on heating.
- The decomposition of monovalent metal nitrate (silver nitrate) is as follows.
\[2AgN{{o}_{3}}\xrightarrow{\Delta }2Ag+2N{{O}_{2}}+{{O}_{2}}\]
- Therefore monovalent nitrates decomposes and forms respective metal, $N{{O}_{2}}$ and ${{O}_{2}}$ on heating.

- So, the correct option is A.

Note: Two moles of silver nitrate decomposes and forms 2 moles of silver metal and 2 moles of nitrogen dioxide and one mole of oxygen as the products on heating. Trivalent metal oxides like aluminum nitrate decompose and form aluminium oxide, nitrogen dioxide and oxygen as the products on heating.