nítrico

Nítrico is the term used in several languages, including Portuguese and Spanish, to refer to nitrogen(V) compounds and, most prominently, to nitric acid (ácido nítrico or ácido nítrico). In chemical nomenclature, nítrico denotes species containing the nitro group or the nitrogen in the +5 oxidation state. The principal example is nitric acid, HNO3, a strong mineral acid that is highly reactive and widely used in industry.

Properties

Nitric acid is a strong, highly corrosive oxidizing acid. Pure acid is colorless, but concentrated solutions often appear yellow due to nitrogen dioxide impurities. It is fully miscible with water and releases heat upon mixing. Concentrated solutions act as powerful oxidizers and can react violently with many organic materials and reducing agents. Fuming nitric acid refers to highly concentrated HNO3 that contains substantial NO2, giving visible vapors.

Production

The dominant industrial route to nitric acid is the Ostwald process. Ammonia is catalytically oxidized to nitrogen monoxide (NO), which is further oxidized to nitrogen dioxide (NO2) and then absorbed in water to form HNO3. Commercial nitric acid is typically about 52–68% HNO3, with higher concentrations (fuming nitric acid) used for specific applications. By-products include nitrogen oxides, which are subject to environmental controls.

Applications

Nitric acid is essential in fertilizer production, serving as a precursor to ammonium nitrate and calcium nitrate. It is also used in the manufacture of explosives and propellants, in nitration reactions for organic synthesis, and in metal processing (pickling and passivation) and electronics manufacturing for etching.

Safety and environmental aspects

Nitric acid is highly corrosive and an oxidizer. It irritates the skin, eyes, and respiratory tract and can cause severe burns. It should be stored away from reducing agents and organic materials, with appropriate containment and ventilation to control fumes and spills. Emissions of nitrogen oxides are regulated due to environmental impact.