Question

In the laboratory preparation of nitric acid, what is the name of reactants?
(A)- Conc sulphuric acid
(B)- Nitre or chile saltpetre
(C)- Conc hydrochloric acid
(D)- Both A and B

Answer 1

Hint: The nitric acid can be obtained by the thermal decomposition of a metal nitrate salt. This is followed by presence of a strong acid acting as a dehydrating agent to produce residual product of nitric acid.

Complete step by step answer:
The chile saltpetre is an alkali metal nitrate salt. That is, sodium nitrate, $NaN{{O}_{3}}$. One of its chief applications is in the nitric acid industry and as an agricultural source of nitrogen as fertilizer.
Sodium nitrate combined with sulfuric acid to produce nitric acid. The reaction is as follows: \[NaN{{O}_{3}}\text{ }+\text{ }{{H}_{2}}S{{O}_{4}}\text{ }\to NaHS{{O}_{4}}\text{ }+\text{ }HN{{O}_{3}}\]

This is a double displacement reaction as the reactants have cations as $N{{a}^{+}}$ and ${{H}^{+}}$,and the anions as $N{{O}_{3}}^{^{+}}$ and $HS{{O}_{4}}^{-}$. Since both of these ions are displaced in the reactant from the product.

In this extractive distillation process with dehydrating agent like concentrated sulphuric acid:
- The reactants are heated by the hot furnace gases due to which vapour of nitric acid is produced.
- The nitric acid vapours get collected in stoneware receivers, after they are cooled/condensed through the water-cooled silica pipes. This is the distillation step.
- The residual of sodium bisulphate solution formed during the reaction is removed by an outlet at the bottom of iron retort.
So, the correct answer is “Option D”.

Note: The nitric acid is a strong acid with highly nitrating, oxidizing, hydrolysing and activating ability making it essential in chemical production and fertilizer industry.
It has high solubility in water and efficiency to make some metals passive, making it commercially suitable.