Nitric Acid
High purity industrial inorganic acid
Overview
Nitric acid (CAS No: 7697-37-2), also known as aqua fortis, is a strong inorganic acid ranging from colorless to yellow in color with a sharp, pungent odor. It is one of the most widely used acids in industry and serves as a fundamental raw material for many industrial processes.
Nitric acid is a powerful oxidizing agent and acid. Concentrated nitric acid can dissolve most metals and reacts violently with organic materials. Industrially, it is typically used in concentrations ranging from 52-68%. Pure nitric acid decomposes under light, acquiring a yellowish color.
Applications
Nitric acid has a wide range of industrial applications:
Fertilizer Production
Used as a primary raw material in the production of nitrogen fertilizers like ammonium nitrate.
Explosives
Used in the production of TNT, nitroglycerin and other nitro compounds.
Metal Processing
Used for metal cleaning, etching and rust removal processes.
Chemical Synthesis
Production of organic nitro compounds, dyes and pharmaceuticals.
Electronics Industry
Used in semiconductor manufacturing and printed circuit board cleaning.
Rocket Fuel
Used as an oxidizer in some rocket propellants.
Technical Specifications
| Property | Value | Unit | Test Method |
|---|---|---|---|
| Chemical Formula | HNO₃ | - | - |
| CAS Number | 7697-37-2 | - | - |
| Molecular Weight | 63.01 | g/mol | - |
| Appearance | Colorless to yellow liquid | - | Visual |
| Odor | Sharp, suffocating | - | Olfactometry |
| Density (20°C, 68%) | 1.413 | g/cm³ | ASTM D4052 |
| Boiling Point (68%) | 120.5 | °C | ASTM D1078 |
| Melting Point | -42 | °C | ASTM D1015 |
| Flash Point | Non-flammable | - | - |
| Vapor Pressure (20°C) | 48 | mmHg | ASTM D2879 |
| Viscosity (20°C) | 0.88 | cP | ASTM D445 |
| pH Value (1% sol.) | 1.0 | - | ASTM E70 |
| Purity | ≥68% | % | ASTM E611 |
| Nitrogen Oxide Content | ≤0.5 | % | ASTM D3864 |
| Chloride Content | ≤0.5 | ppm | ASTM E412 |
Safety Information
Hazard Symbols and Statements
Corrosive Oxidizing Toxic Health Hazard
Personal Protective Equipment (PPE)
- Acid-resistant gloves (neoprene or nitrile)
- Chemical goggles or face shield
- Appropriate respiratory protection against acid vapors
- Chemical-resistant apron or work clothing
- Acid-resistant footwear or boots
Storage Conditions
- Store in a cool, well-ventilated area
- Keep separate from oxidizers and bases
- Store in stainless steel, polyethylene or glass containers
- Display "Corrosive Material" signs in storage area
- Storage temperature: 15-25°C
Fire Fighting
- Suitable extinguishers: Dry chemical, CO₂
- Water mist may be used but avoid water jet
- Trained personnel should intervene with appropriate protective equipment
- Use respiratory protection against acid vapors during fire fighting
Handling and Storage
Handling
- Ensure containers are tightly closed during transport
- Use equipment made from acid-resistant materials
- Use stainless steel tankers for bulk transport
- Avoid eating, drinking, or smoking during handling
- Keep neutralizing materials available for spills and leaks
Storage
- Store in stainless steel, glass, or special plastic (HDPE, PTFE) containers
- Do not contact with metals like aluminum, iron, or zinc
- Provide ventilation systems in storage tanks
- Keep acid neutralizing materials in storage areas
- Provide proper insulation to prevent freezing in cold weather
Spill Response Measures
- Remove all ignition sources
- Use appropriate respiratory protection and chemical protective clothing
- Neutralize with sodium bicarbonate or calcium carbonate
- Absorb small spills with absorbent materials (sand, vermiculite)
- For large spills, seek help from professional cleaning teams
- Wash spilled area with plenty of water
Regulatory Information
GHS Classification
- Corrosive/Skin Corrosion Category 1B
- Serious Eye Damage/Eye Irritation Category 1
- Oxidizing Liquid Category 3
- Specific Target Organ Toxicity (Single Exposure) Category 3
Key Regulations
- REACH: Registered
- CLP: Compliant
- FDA: Approved for specific applications
- NFPA 704: Health 4, Flammability 0, Reactivity 3
International Regulations
- European Union: Subject to Directive 2008/58/EC
- USA: Listed in EPA TSCA inventory
- China: Present in IECSC list
- Japan: Present in ISHL list
Environmental Information
Environmental Impact
Nitric acid breaks down rapidly in nature through biological processes. When mixed with water sources, its high water solubility may show moderate toxic effects on aquatic organisms. Contamination of groundwater should be prevented.
Biodegradation
- Air: 1-2 week half-life through photochemical reactions
- Water: Degrades within 1-5 days through microbial activity
- Soil: Rapid degradation through microbial activity
Waste Management
- Classified as hazardous waste
- Can be neutralized (with sodium bicarbonate) before disposal
- Large quantities must be incinerated in licensed hazardous waste facilities
- Dispose according to local regulations
- Must be neutralized before discharge into sewers
Frequently Asked Questions
How is nitric acid produced?
Nitric acid is industrially produced primarily through the Ostwald process. This process begins with the oxidation of ammonia over a platinum-rhodium catalyst at high temperatures.
What is the difference between nitric acid and sulfuric acid?
Nitric acid is a strong oxidizing acid and reacts violently with organic materials. Sulfuric acid is a stronger dehydration agent and has a higher boiling point.
Which metals does nitric acid react with?
Nitric acid reacts with metals like aluminum, iron, zinc, and magnesium, releasing various gases. Stainless steel, glass, and certain plastics are suitable for nitric acid storage.
What is the shelf life of nitric acid?
When stored in properly sealed containers, nitric acid has no significant shelf life limit. However, long-term storage may result in concentration reduction due to water absorption.
What should I do if nitric acid contacts skin?
Immediately rinse with plenty of water for at least 15 minutes. If contamination is extensive, remove all clothing. Seek medical help if irritation persists. For eye contact, rinse immediately with water and consult an eye doctor.