Question

The brownish yellow color of nitric acid is removed by:
A.Bubbling air through warm acid
B.Bubbling acid
C.Passing ammonia through acid
D.Adding little Mg powder

Answer 1

Hint: We can prepare nitric acid from nitrogen oxide in water. Nitrogen dioxide gets absorbed in water to yield nitric acid. The remaining solution of acid-in-water is dehydrated by distilling it with sulfuric acid. We can use nitric acid in the formation of ammonium nitrate for fertilizers, and in dyes production.

Complete step by step answer:
We can write the chemical formula of nitric acid as $HN{O_3}.$ it is a mineral acid and is highly corrosive. The pure compound of nitric acid does not have any colour. We can call nitric acid as fuming nitric acid, when the solution has more than 86% nitric acid.
Based on the amount of nitrogen dioxide, we can classify fuming nitric acid as,
Red fuming nitric acid-Nitric acid concentration is more than 86%.
White fuming nitric acid-Nitric acid concentration is more than 95%.
We can use nitric acid as nitrating agent in the nitration process of an organic molecule. We can also use nitric acid as oxidizing agent.
We can react sodium nitrate (or) any nitrate salts with sulfuric acid, distill the mixture at the boiling point of nitric acid, which is ${83^ \circ }C.$ We can find a nonvolatile residue of the metal remaining in the distillation vessel. We can also convert the obtained red fuming nitric acid to white fuming nitric acid.
We can write the chemical reaction as,
$NaN{O_3} + {H_2}S{O_4}\xrightarrow{{}}HN{O_3} + NaHS{O_4}$
Nitric acid, which is produced in the laboratory, is yellow because of the dissolution of nitrogen dioxide that is produced from thermal decomposition.
$4HN{O_3}\xrightarrow{{}}4{H_2}O + 4N{O_2} + {O_2}$
When we bubble carbon dioxide through the acid, it changes colourless, as it drives out nitrogen dioxide from warm acid that is oxidized to get nitric acid.
$\therefore $Option A is the correct answer.

Note:
We can also prepare nitric acid from Ostwald’s process. We could use nitric acid as rocket propellant, as oxidant, in woodworking, in liquid-fueled rockets as an oxidizer. The pure form of nitric acid is used to remove warts. In electrochemistry, nitric acid is employed as a chemical doping agent.