Nitrous acid is a conjugate acid of nitrogen that exists only in solution form. It is a weak and monoprotic acid known in the gas phase and in the form of nitrite salts. It is investigated for its applicability towards treatments for heart attacks, pulmonary hypertension in infants, and Pseudomonas aeruginosa infections. It is weak acid that can form water-soluble nitrites and stable esters.

Its appearance is a pale-blue solution. It is a nitrogen oxoacid which is when heated to decomposition it emits highly toxic fumes of nitroxides. This acid is unstable but decompose to nitric acid. Nitrous acid is the aqueous solution of nitrogen trioxide that is moderately strong. It is a rapid oxidizing and diazotizing agent. It oxidizes hydrogen sulfide to sulfur and forms ammonia. This oxidation is acidity dependent. This acid of nitrate has unpleasantly bitter odor.

It is extremely volatile and rises in thick fumes; boils at the low temperature. It has a specific gravity of 1.45. In gaseous state, nitrous acid remains unchanged. When mixed with water an effervescence takes place with the emission of nitrous gas. This monobasic acid supports the combustion of charcoal, when it is introduced into it in a state of combustion. It reacts with single-valent cations to form water-soluble salts. It is incompatible with anilines. It is flammable by chemical reactions. It may explode on contact with phosphorous compounds.

CAS NO :- 7782-77-6

USES AND APPLICATIONS FOR NITROUS ACID

• It is utilized in the preparation of diazonium salts from amines.
• It is used in the preparation of azo dyes in Sandmeyer reaction.
• It acts to remove the toxic nature in potentially explosive compound sodium azide.
• Nitrous acid functions as an oxidizer in liquid fuel rockets.

PHYSICAL PROPERTIES

It can behave as an oxidizing agent with Sulphur oxide and hydrogen Sulphide. But this happens in certain circumstances. Nitrous acid may be obtained by adding a strong acid such as hydrochloric acid to nitrite solution.