Overview
Nitric acid (HNO₃) is a pivotal industrial chemical with a history dating back to alchemy. It is produced industrially via the Ostwald process, oxidizing ammonia to nitric oxide, then further to nitrogen dioxide, which dissolves in water to form nitric acid. Its high reactivity and oxidizing properties make it indispensable in modern manufacturing and laboratory processes. Concentrated nitric acid typically ranges from 68% to 70% in commercial grades, while fuming nitric acid contains over 86% HNO₃. Its applications span agriculture (fertilizers), military (explosives), and metallurgy (metal purification and etching).
Physical and Chemical Properties
Nitric acid is a colorless to pale yellow liquid with a pungent, choking odor. It is hygroscopic and forms azeotropes with water. As a strong acid, it dissociates completely in aqueous solutions, releasing hydrogen ions and nitrate anions. Its oxidizing power is evident in reactions with metals (e.g., copper) and organic compounds, often producing nitrogen dioxide (NO₂), a toxic brown gas. Key chemical behaviors include nitration (adding nitro groups to organic molecules) and passivation (forming protective oxide layers on metals like aluminum). Its density and boiling point vary with concentration; for example, azeotropic 68% HNO₃ boils at 120°C.
Main Applications
The largest use of nitric acid is in fertilizer production, where it neutralizes ammonia to create ammonium nitrate, a high-nitrogen fertilizer. In explosives manufacturing, it nitrates organic compounds like toluene to form TNT or glycerin to produce nitroglycerin. Industrially, it serves as an etching agent for metals (e.g., stainless steel) and a cleaning agent in semiconductor fabrication. Lesser-known uses include uranium processing, dye synthesis, and as a rocket propellant oxidizer. In laboratories, diluted nitric acid is a common reagent for qualitative analysis.
Safety and Storage
Nitric acid poses severe health hazards: inhalation causes lung damage, skin contact leads to chemical burns, and ingestion can be fatal. Always use corrosion-resistant PPE (gloves, goggles, face shields) and work in fume hoods. Spills require neutralization with bases (e.g., sodium bicarbonate) and ample water flushing. Storage demands dark glass or polyethylene containers to prevent photodegradation. Avoid contact with organic materials (wood, paper) due to fire risks. Concentrated acid should be kept below 25°C, separate from reducing agents. Facilities must comply with OSHA and NFPA standards for hazardous chemical storage.
B2B Procurement Guide
Bulk buyers should prioritize suppliers with ISO 9001 certification and SDS documentation. Key specifications include concentration (e.g., 68% vs. fuming), purity (technical grade vs. reagent grade), and packaging (IBC totes, drums). Transport requires UN-approved containers and hazmat labeling. For international shipments, verify compliance with regional regulations (e.g., REACH in Europe). Negotiate contracts with volume discounts but confirm stability guarantees—long-term storage can degrade quality. Spot prices fluctuate with ammonia (feedstock) market trends.