Question

What is the action of conc. Nitric acid on,
a) Zinc metal
b) ${{P}_{4}}$ - molecule
c) ${{S}_{8}}$ - molecule?

Answer 1

Hint: The molecular formula of nitric acid is $HN{{O}_{3}}$. Generally metallic nitrate derivatives are going to be prepared by using concentrated nitric acid. By dissolving the metals in the nitric acid we can prepare metallic nitrates.

Complete Solution :
- In the question it is given what products are going to form when conc. Nitric acid reacts with the given metals.

a) Reaction of conc. Nitric acid with Zinc metal.
- Generally zinc metal is not going to react with conc. Nitric acid because when zinc metal is exposed to the environment it forms an oxide layer on the surface of zinc. The oxide layer won’t allow the zinc metal to react with conc. Nitric acid.
- But Zinc metal reacts with dilute nitric acid and forms zinc nitrate as the product.
- The chemical reaction of zinc with dil. Nitric acid is as follows.
\[Zn+2HN{{O}_{3}}\to Zn{{(N{{O}_{3}})}_{2}}+{{H}_{2}}\]

b) Reaction of conc. Nitric acid with ${{P}_{4}}$ - molecule.
- Conc. Nitric acid reacts with phosphorus and forms phosphoric acid and the chemical reaction is as follows.
\[{{P}_{4}}+20HN{{O}_{3}}\to 4{{H}_{3}}P{{O}_{4}}+20N{{O}_{2}}+4{{H}_{2}}O\]

c) Reaction of conc. Nitric acid with ${{S}_{8}}$ - molecule.
- Conc. Nitric acid reacts with sulphur and forms sulphuric acid and the chemical reaction is as follows.
\[{{S}_{8}}+48HN{{O}_{3}}\to 8{{H}_{2}}S{{O}_{4}}+48N{{O}_{2}}+16{{H}_{2}}O\]

Note: Generally metals reacts with concentrated acids and forms respective metallic acids as the products. Like that phosphorus reacts with nitric acid and forms phosphoric acid and sulphur reacts with nitric acid and forms sulphuric acid as the products.