Nitric Acid (HNO3) [Definition, physical characteristics, & uses]

Nitric acid is a hydrogen oxoacid with a chemical formula of HNO₃. It appears as a colourless liquid in its pure form. Its synonyms include hydrogen nitrate, aqua fortis, Acidum nitricum, nitryl hydroxide, spirit of nitre, azotic acid, nitryl hydroxide, engraver’s acid, acido nitrico and nitricum acidum just to mention a few. It is referred to as red fuming nitric acid when its concentration is above 86% and white fuming nitric acid when its concentration is above 95%.  Red fuming nitric acid appears as a pale yellow to a reddish-brown liquid that generates red-brown fumes and has a suffocating odour. Adverse health effects may come as a result of exposure to high concentrations of the chemical for short periods and prolonged exposure for long periods. The chemical is highly corrosive and highly soluble in water. When exposed to heat or atmospheric humidity, the chemical decomposes to form nitrogen peroxide. The chemical is also able to attack all base metal oxides with the exception being aluminium and special chromium steels.

Application of Nitric Acid

1. It is used as a dye intermediate.
2. It is used as an acidifier in pharmaceutic aid.
3. It is used in the manufacture of organic and inorganic nitrates and nitro compounds for fertilizers.
4. It is used in the manufacture of nylon precursors.
5. It is used in the manufacture of explosives.
6. It is used in rocket propulsion as an oxidizer.
7. It is used in wood finishing at low concentrations to artificially age maple and pine.
8. It is used for etching and cleaning metals.
9. It is used in processing spent nuclear fuel.
10. It is used in photoengraving.
11. It is used in ore flotation.
12. It is used in metallurgy to purify precious metals such as gold and silver.
13.  It is used in the production of coal tar and drugs.
14. It is used in the food industry to help in cleaning food and equipment.
15. It is used in the colourimetric test to differentiate between heroin and morphine.
16. It is used in the old school practice as an escharotic for warts and warty tumours, chancres, phagedenic ulcers, and poisoned bites.
17. It is used in the electronic industry for cleaning silicon wafers.
18. It is used in cleaning glasses when making silver mirrors before silvering.
19. It is used in making nitrate salts.