Nitric acid is a colorless acid with a strong acidic character and molecular formula HNO3. Other names of nitric acid include the spirit of niter, and aqua fortis (Latin for “strong water”). Nitric acid, in its pure form, appears colorless but with time, it might turn into a yellow cast.
Concentrated solution (69-71%) of nitric acid breaks down over time emitting yellow or brownish smoke or vapor (fumes) of nitrogen dioxide giving it’s the name of fuming acid. Nitric acid turns blue litmus red, is among the strongest oxidizing agents, and readily forms an aqueous solution.
Lab-scale synthesis methods of nitric acid include the reaction of sodium nitrate with sulfuric acid. Nitric acid is obtained by distillation of the reaction mixture. Industrial-scale production of nitric acid is largely by a combination of oxygen with ammonia. This produces oxides of nitrogen that are absorbed in water to produce nitric acid.
Nitric acid fumes are corrosive and poisonous to humans having an irritating odor. Exposure to nitric acid is dangerous and can lead to irritation of the eyes, skin, and mucous membrane. Long-term exposure can lead to delayed pulmonary edema, pneumonitis, bronchitis, and dental erosion.
Nitric acid is a common reagent used in laboratories, research facilities, and manufacturing operations. Common applications include the manufacture of ammonium nitrate used in making fertilizers. Other examples include the synthesis of dyes and explosives like TNT. Nitric acid is also used in the synthesis of plastics and polymers.