Nitric acid

Nitric acid (CAS 7697-37-2), also known as spirit of niter, is a strong inorganic acid and powerful oxidizing agent used in industrial chemistry for acidification and metal processing.

Where is Nitric acid used?

• Agriculture: input for producing ammonium nitrate, linking bulk acid procurement to crop nutrition supply chains
• Metal finishing and electronics: etches, passivates, and cleans copper, stainless steel, and semiconductor substrates
• Pharmaceutical and fine chemical: nitration reactions that introduce nitro groups into active pharmaceutical intermediates
• Mining and hydrometallurgy: dissolves base and precious metals during leaching and refining
• Its reactivity with metals and organic substrates makes it a primary feedstock in manufacturing.
• Used in dye production.
• Used in explosives production.
• Used in horticulture to acidify soil by acidifying irrigation water.
• Used in irrigation systems to remove and prevent blockages by eliminating impurities and calcium sediment that clog drippers.

Formulation notes

• For water with 7 meq/L bicarbonate, use 581 ml of nitric acid per 1,000 liters of irrigation water to reduce bicarbonate to 0.5 meq/L.
• Must not be mixed with metal-based micronutrients (zinc, manganese, copper, etc.) to avoid violent oxidations producing nitrous oxide.

Typical specification

• Boiling point 121°C, melting point -41.6°C, relative density 1.4, miscible with water at 20°C, vapor pressure 6.4 kPa at 20°C, relative vapor density 2.2.
• White fuming nitric acid (CAS 52583-42-3) contains more than 97.5% nitric acid, less than 2% water and less than 0.5% nitrogen dioxide.
• The assay specification for nitric acid 20% technical grade is 19.5 to 20.5% HNO3.

Regulatory status

• For transport, nitric acid is UN Class 8 (corrosive) with subsidiary risk 5.1 (oxidizing) and Packing Group I.
• Classified as an oxidizer (H272) that may intensify fire.
• The EU occupational exposure limit is 2.6 mg/m3 and 1 ppm as STEL.

Storage, packaging and handling

• As a strong acid, it reacts violently with bases and is corrosive to metals, producing flammable/explosive hydrogen gas.
• Must be kept in adequately sealed containers away from direct sunlight at temperatures below 20°C.
• Store separately from combustible substances, reducing agents, bases, organic chemicals, food and feed, in a cold, dry, well-ventilated place, only in the original packaging.

Frequently asked questions about Nitric acid

What concentration is preferred when buying nitric acid?

A concentration of 65–68% is the preferred grade when buying nitric acid.

What does oxidation initiated by nitric acid yield?

Oxidation initiated by nitric acid yields adipic acid, which is further used to produce synthetic fibres such as nylon.

Technical content is compiled and updated by the SoleChem product team from public technical sources; the certificate of analysis (COA) governs product-specific specifications.