Nitric Acid Chemical Formula
Nitric acid (chemical formula HNO3) is one of the most widely uses in heavy chemicals like acidic fertilizer production plant and explosives manufacture process and storage million tonnes of each year. Pure nitric acid is a colorless liquid, freezing point -41.6°C, and boiling point 82.6°C and concentrated water solution have properties to photochemical dissociation and turn brown by liberating nitric oxide with very low pH level. Nitric acid manufacture by catalytic oxidation of ammonia by Oswald process and laboratory preparation find by distillation of reagent sodium or potassium nitrate with concentrated sulfuric acid. Commercially available HNO3 has a concentration of about 98 percent and fuming yellow HNO3 get by dissolving extra NO2.
Structural Formula of Nitrate Ion
The HNO3 gas molecule has a planner structure and the same structure probably holds for crystal solid. The N-O chemical bond distance in nitrogen dioxide are equal. The third N-O polar bond distance longer than the corresponding single bond. Therefore, the structures consist of roughly SP2 hybridization at the nitrogen atom involving resonance hybrids. The nitrate ion symmetrical planner with N-O bond distance 1.22, consist bond order of 1 and 1/3.
Nitric Acid Production Process
Manufacture of pure nitric acid done by catalytic oxidation of ammonia (Ostwald process). But ammonia undergoes different types of oxidation reactions under various conditions.
- In the air, NH3 reacts but little to form nitrogen but in pure oxygen, it burns to form nitrogen and water.
4NH3 + 3O2 → 2N2 + 6H2O
- When hot platinum gauze catalyst use, the mixture of NH3 and air (1:7) oxidized mostly to NO.
4NH3 + 5O2 → 4NO + 6H2O
- The liberated heat keeps the catalyst hot. Therefore, NO cooled and mixed with oxygen to give dioxide. When the product passed into warm water under pressure to give HNO3.
4NO2 + 2H2O + O2 → 4HNO3
Chemical Activities of HNO3
Chemical activities of nitric acid discussed under neutralization reaction, oxidation reaction, and nitrating reagent. In water solution, HNO3 shows strong acid properties. Concentrated HNO3 in the presence of H2SO4 attack aromatic hydrocarbon and thair derivatives to form nitro compounds. Some oxidizing activities are shown in the following reactions.
Cu + 4HNO3(conc) → 3Cu(NO3)2 + 2NO2 + 2H2O
Cu + 8HNO3(diluted) → 3Cu(NO3)2 + 2NO + 2H2O
Uses of Nitric Acid (HNO3)
The main storge consumption about 80% of nitric acid uses in the manufacture of ammonium nitrate (NH4NO3) which chiefly used as an acidic fertilizer plant but also use as an explosive in mining.
- It also uses (5 -10%) in making cyclohexanone and caprolactam as a route to nylon.
- HNO3 confined to nitration chemical reaction to produce nitroglycerine, nitrocellulose, and trinitrotoluene (TNT).
- These acids also used in the pickling of metals surface, oxidizer in rocket fuel, and in the manufacture of various nitrate.
Red fuming nitric acid finds by dissolving N2O4, which is a superior nitrating reagent. A mixture of concentrated nitric acid and sulfuric acid also uses as a nitrating reagent by the storage of nitronium ion (NO2+).