Nitric Acid
CAS 7697-37-2 HNO3
- CAS number
- 7697-37-2
- EC number
- 231-714-2
- Formula
- HNO3
- Molar mass
- 63.01 g/mol
- HS code
- 2808.00
Supply of Nitric Acid
- Grades
- Weak acid at 52–68% carries the fertilizer and general industrial trade, with 68% being the azeotrope and the strongest concentration simple distillation reaches. Concentrated acid runs 98–99%, and the fuming grades are white (very low nitrogen dioxide) and red (nitrogen dioxide dissolved deliberately). Technical, reagent and low-metal electronic grades are traded; semiconductor grades specify metals in parts per billion. Specify strength, grade and inhibitor status.
- Packaging
- 35 kg jerricans and carboys · Drums (~250–330 kg net), IBC · Stainless or aluminium ISO tanks, road and rail tankers · Bulk
- Documents
- CoA, SDS and TDS on request; certificate of origin where the destination requires it.
- Delivery
- Worldwide, including the United States, Canada, the United Kingdom, Germany and the rest of the EU, the United Arab Emirates, India, Singapore, Malaysia and Australia. Quoted EXW, FOB, CIF or DAP.
Nitric acid is a strong acid made from ammonia. About three quarters of it is turned into nitrogen fertilizers such as ammonium nitrate. The rest is used to make nylon and foam plastics and to clean and treat stainless steel. Because it can also be used to make explosives, its sale is regulated, and buyers state what they will use it for.
Technical details
Nitric acid is made by oxidising ammonia over a platinum catalyst, so its cost tracks natural gas, and roughly three quarters of world output goes straight back into nitrogen fertilizer as ammonium nitrate, calcium ammonium nitrate and nitrophosphates. The remainder goes into adipic acid for nylon, nitrobenzene on the way to polyurethanes, stainless pickling and passivation, electronics etching, and precious-metal and rare-earth work. Two points apply to most enquiries. The 68% grade is an azeotrope, so it is the ceiling that ordinary distillation reaches and anything stronger costs more because it needs a different process. And nitric acid is the most tightly regulated of the mineral acids: in the EU it is a restricted explosives precursor above 3% by weight, which makes a documented professional end use part of the transaction rather than a formality. Ehlinar supplies weak, concentrated and fuming grades against a stated end use.
Appearance: A clear, colourless liquid when fresh that yellows in storage and in light as dissolved nitrogen dioxide builds up; the 68% azeotrope has a density around 1.41 g/mL and boils at about 121 °C. Concentrated and fuming grades give off choking brown fumes in air. Red fuming acid is deep orange to brown from the nitrogen dioxide held in it.
Applications
How we supply
- Certificate of Analysis (CoA), lot-specific where available
- Safety Data Sheet (SDS / MSDS)
- Technical Data Sheet (TDS)
- Certificate of Origin / Certificate of Conformity
Independent third-party inspection can be arranged on request, with the agency and scope agreed per trade. Representative samples can be requested for qualification, subject to supplier availability. We recommend incoming quality control against the agreed CoA.
Quoted on standard Incoterms (e.g. EXW, FOB, CIF, DAP) as agreed per trade. Delivery region, packaging and grade are confirmed per quote.
Documents and services above are subject to supplier availability and confirmed per quote; nothing here is an offer.
Typical / indicative values — not a binding specification
| Property | Typical |
|---|---|
| Commercial strengths | 52–68% weak; 98–99% concentrated; white and red fuming |
| Azeotrope | ~68% — the ceiling of simple distillation |
| Density at 20 °C (68%) | ~1.41 g/mL |
| Boiling point (68%) | ~121 °C |
| Transport class | Class 8; oxidiser subsidiary risk above ~65% |
| Materials of construction | 304L/316L stainless for weak acid; aluminium above ~80% — never carbon steel, copper or brass |
Also known as
Aqua fortis · Spirit of nitre · Azotic acid · Engraver's acid · WFNA / white fuming nitric acid · RFNA / red fuming nitric acid
Frequently asked questions
- Why is nitric acid sold at 68% so often?
- Because 68% is the azeotrope. Above that concentration the vapour has the same composition as the liquid, so ordinary distillation cannot push it further — reaching 98% needs dehydration with sulfuric acid or magnesium nitrate, or a purpose-built concentrated-acid plant. That step is why concentrated acid costs meaningfully more per unit of acid than weak acid, and why a buyer who does not truly need the strength should specify weak.
- Why has my nitric acid turned yellow?
- Dissolved nitrogen dioxide, formed as a little of the acid decomposes under light and warmth. In a technical grade this is normal ageing and usually does not affect the duty; store it cool and out of sunlight to slow it. It matters where colour or oxidising strength is part of the specification, and it is deliberate in red fuming acid, which is nitrogen dioxide dissolved on purpose. If a low-colour material is required, say so and specify white fuming or a fresh-dated weak grade.
- What should nitric acid be stored in?
- Material selection differs from most acids. Weak acid up to about 68% goes in 304L or 316L stainless steel. Concentrated acid above roughly 80% is normally handled in aluminium, which passivates in strong nitric but is attacked by the weak acid — so the two strengths are not interchangeable in the same tank. Carbon steel, copper, brass and bronze are never used, and organics such as most gasket elastomers need checking individually. PTFE is the usual safe seal.
- Is nitric acid restricted?
- Yes, and more tightly than the other mineral acids. Under the EU explosives-precursors regulation it is a restricted substance above 3% by weight: it cannot be made available to members of the general public, professional users must be identified and state their end use, and suspicious transactions are reportable. Comparable controls exist in most other jurisdictions. In practice this means a legitimate industrial order needs company identification and a stated application before an offer, and it is normal for a supplier to decline an order that will not supply them.
- What is aqua regia?
- A mixture of concentrated nitric and hydrochloric acid, classically one part to three, which dissolves gold and platinum where neither acid does so alone. The nitric oxidises the metal while the hydrochloric supplies chloride to hold the resulting ion in solution. It is made fresh because it decomposes on standing and pressurises a closed container, so it is mixed at the point of use rather than bought and stored.
- Why is nitrogen dioxide exposure treated so seriously?
- Because the gas is only mildly irritating at the time and the real injury is delayed. Fluid can accumulate in the lungs many hours after an exposure that felt trivial, in someone who walked away apparently unharmed. That delay is the reason inhalation is handled as a medical emergency and the person is observed, rather than sent home because they feel well.
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Figures and identifiers here are compiled from public references and provided for general information; they are indicative, not a specification. See all products.