Nitric Acid
HNO₃
Nitric acid (HNO₃, CAS 7697-37-2) is a strong, oxidising mineral acid. The industrial standard is the 68-70% azeotropic grade, which is what most plants dose for pH control of alkaline streams, metal precipitation, descaling and pickling of process equipment, and controlled oxidation. It is corrosive and must be stored in acid-resistant containers away from organics. CHIMI ART supplies technical-grade nitric acid across Egypt in 200 L drums, 1,000 L IBCs and bulk tankers, with a certificate of analysis for every delivery.
Product Overview
Nitric acid (HNO₃, CAS 7697-37-2) is a strong, oxidising mineral acid. The industrial standard is the 68-70% azeotropic grade, which is what most plants dose for pH control of alkaline streams, metal precipitation, descaling and pickling of process equipment, and controlled oxidation. It is corrosive and must be stored in acid-resistant containers away from organics. CHIMI ART supplies technical-grade nitric acid across Egypt in 200 L drums, 1,000 L IBCs and bulk tankers, with a certificate of analysis for every delivery.
Technical Specifications
- Chemical Formula
- HNO₃
- CAS Number
- 7697-37-2
- Appearance
- Colorless liquid with sharp odor
- Concentration
- 68-70% HNO₃
- Specific Gravity
- 1.40-1.42
- pH Range
- < 1.0
- Solubility
- Fully miscible with water
- Available Packaging
- 200L drums · 1000L IBC · Bulk tanker
- Shelf Life
- 12 months
- Storage Conditions
- Acid-resistant containers
| Property | Value |
|---|---|
| Chemical Formula | HNO₃ |
| CAS Number | 7697-37-2 |
| Appearance | Colorless liquid with sharp odor |
| Concentration | 68-70% HNO₃ |
| Specific Gravity | 1.40-1.42 |
| pH Range | < 1.0 |
| Solubility | Fully miscible with water |
| Available Packaging | 200L drums · 1000L IBC · Bulk tanker |
| Shelf Life | 12 months |
| Storage Conditions | Acid-resistant containers |
Applications
Dosing Guidelines
For pH control, meter nitric acid slowly into a well-mixed stream and control against a calibrated pH loop until the target value is reached; acid demand depends on the stream's alkalinity, so it is best established by titration and confirmed in a plant trial. For cleaning and descaling duties, diluted solutions of typically 5-15% are used, circulated until scale is dissolved and then rinsed to neutrality. Always add acid to water when diluting, never water to acid. Start at the lower end of any range and increase stepwise while monitoring results — overdosing wastes acid and drives the pH below target.
How It Works
Nitric acid works through two complementary actions: acidity and oxidation. In water, HNO₃ dissociates completely, releasing hydrogen ions that neutralize hydroxide and carbonate alkalinity, which makes it an effective pH-control agent for alkaline streams. The nitrate ion is also a strong oxidizer: it dissolves most base metals and converts them into soluble metal nitrates, the basis of pickling and metal-recovery applications. On stainless steel the same oxidizing action is beneficial rather than destructive — it regenerates the chromium-oxide passive layer, which is why nitric acid is preferred for cleaning and descaling stainless equipment. Reacting with carbonate scale, it converts calcium and magnesium deposits into soluble nitrates with release of carbon dioxide, restoring fouled heat-transfer surfaces.
Usage Tips
Store nitric acid in acid-resistant containers — HDPE drums or suitable stainless-steel tanks — in a cool, ventilated area away from organics, reducing agents and bases; shelf life is 12 months in original sealed packaging. Keep containers closed and vented per the SDS, as the acid is corrosive and gives off sharp fumes. Always add acid to water when diluting. Handlers need acid-resistant gloves, splash goggles, face shield and apron, with eyewash and safety shower nearby, and a neutralizing agent such as soda ash available for spills.
What is nitric acid (HNO₃)?
Nitric acid is a strong, oxidising mineral acid, HNO₃, molar mass 63.01 g/mol. Industrially it is supplied as a water solution — the standard grade is 68–70 %, the concentration at which the acid and water form a constant-boiling mixture (about 120 °C) that cannot be strengthened further by simple distillation. It is colourless when fresh, fully miscible with water, fumes on contact with humid air and slowly yellows as light decomposes a little of it into nitrogen dioxide.
Two properties do the work: it is a strong acid (fully dissociated, pH below 1 as supplied) and the nitrate ion is a powerful oxidiser. The acid dissolves scale and most base metals; the oxidising power is what passivates stainless steel instead of attacking it.
68 %, 70 % or fuming — which grade do you need?
For pickling, passivation, descaling, pH control and general chemical-process duty, the answer is almost always the 68–70 % technical grade that CHIMI ART supplies: it is the strongest concentration that can be made and stored without fuming, it is what the ASTM passivation practices and most plant procedures are written around, and it dilutes cleanly to the 5–15 % working strengths used for cleaning. Concentrations above about 86 % — white and red fuming nitric acid — are nitration and propellant chemistry, hazardous to store and rarely justified outside those uses; lower dilutions are cheaper to buy ready-made only when freight is short.
When a procedure says "68 %" and the drum says "70 %", nothing is wrong: both sit inside the azeotropic band and behave identically in use. The certificate of analysis states the actual assay of each delivery, which is the number to use for dilution calculations.
Uses: pickling and passivation, pH control, descaling and metal recovery
On stainless steel, nitric acid removes free iron and embedded particles and rebuilds the chromium-oxide passive film — the passivation treatments in ASTM A967 run nitric acid baths at roughly 20–55 % by volume, depending on the alloy and treatment, and ASTM A380 covers the cleaning, descaling and pickling steps around them. Mixed with hydrofluoric acid it pickles stainless mill scale; on its own it is the preferred descaler for stainless heat exchangers and process equipment because it does not attack the base metal.
In water and effluent plants it neutralises alkaline streams where sulphuric or hydrochloric acid would add unwanted sulphate or chloride; in metal finishing it brightens and strips; in chemical processing it is the feedstock for nitrates and nitration. Every one of those duties starts from the same 68–70 % drum, tanker or IBC.
Handling, storage and transport
Nitric acid is corrosive and an oxidiser: it must be stored away from organic materials, reducing agents, bases and other acids, in acid-resistant containers — HDPE drums and IBCs or stainless-steel tanks — in a cool, ventilated area, with containers closed and vented as the safety data sheet specifies. Diluting is always acid into water, never the reverse. Handlers need acid-resistant gloves, splash goggles, face shield and apron, with an eyewash and safety shower nearby; the NIOSH recommended exposure limit is 2 ppm as an 8-hour average and 4 ppm short-term.
For transport it travels as UN 2031, hazard class 8 (corrosive) with an oxidiser subsidiary risk, packing group II at the 65–70 % strength supplied. Shelf life in sealed original packaging is 12 months; the assay on the certificate of analysis, not the label, is what to use for dosing.
| Property | Value |
|---|---|
| Chemical formula | HNO₃ |
| CAS / EC number | 7697-37-2 / 231-714-2 |
| Molar mass | 63.01 g/mol |
| Concentration supplied | 68–70 % HNO₃ (technical grade, azeotropic strength) |
| Specific gravity (20 °C) | 1.40–1.42 |
| Molarity at 68 % | about 15 mol/L |
| Boiling point of the azeotrope | about 120 °C |
| pH (as supplied) | < 1 |
| Transport classification | UN 2031, Class 8 (5.1), PG II |
| Packaging | 200 L drums, 1,000 L IBCs, bulk tanker |
| Shelf life | 12 months in sealed original packaging |
Standards & references
- NIOSH NPG 0447NIOSH Pocket Guide to Chemical Hazards — nitric acid: exposure limits (REL 2 ppm TWA, 4 ppm STEL), incompatibilities and first-aid measures.
- PubChem CID 944Nitric acid — physical and chemical property record (molar mass, density, boiling behaviour, hazard classification).
- ASTM A967/A967M-25Standard specification for chemical passivation treatments for stainless steel parts — the nitric-acid passivation treatments and their concentration, temperature and time ranges.
- ASTM A380/A380M-25Standard practice for cleaning, descaling, pickling and passivation of stainless steel parts, equipment and systems.
Certifications & Compliance
Frequently Asked Questions
What is nitric acid (HNO₃) used for in industry?
Nitric acid is a strong mineral acid used industrially for metal pickling and passivation of stainless steel, dairy and food-processing equipment cleaning (CIP), fertilizer production (ammonium nitrate), explosives manufacturing, electroplating bath preparation, and laboratory reagent applications. CHIMI ART supplies technical-grade 68-70% HNO₃ for these applications.
What concentration of nitric acid does CHIMI ART supply?
We supply technical-grade nitric acid at 68-70% concentration (azeotropic strength), which is the standard industrial form. This is fuming-free, colorless to pale yellow, and meets the purity specifications required for descaling, pickling, and chemical-process feedstock applications. Higher concentrations (red fuming or white fuming HNO₃) and lower dilutions are available on request.
What is the chemical formula and CAS number of nitric acid?
Nitric acid has the chemical formula HNO₃ (molecular weight 63.01 g/mol) and CAS registry number 7697-37-2. EINECS/EC number 231-714-2, UN number 2031 (Class 8 corrosive, Packing Group II). Always reference these identifiers on procurement, transport, and SDS documentation.
How is nitric acid used for cleaning and descaling?
Diluted nitric acid solutions (typically 5-15% by volume) are used to dissolve mineral scale (calcium carbonate, calcium sulfate) and remove rust and oxide layers from stainless steel surfaces, heat exchangers, boilers, evaporators, and food-grade tanks. Unlike hydrochloric acid, HNO₃ passivates stainless steel rather than corroding it, making it the preferred descaler in dairy, beverage, and pharmaceutical CIP cycles.
How should nitric acid be stored and handled safely?
Store in HDPE drums or stainless-steel 304L/316L tanks in a cool, ventilated area away from organics, reducing agents, and bases. Operators must wear acid-resistant gloves (neoprene or PVC), splash goggles, face shield, and chemical-resistant apron. Provide emergency eyewash and safety shower within reach. Keep neutralizing agent (soda ash) on hand for spills. Refer to the Safety Data Sheet (SDS) for full handling, transport, and emergency-response procedures.
What is the molecular mass of nitric acid?
63.01 g/mol (H 1.008 + N 14.007 + O 3 × 15.999). A 68 % solution with a density of about 1.41 g/mL therefore contains roughly 960 g of HNO₃ per litre, which is about 15 mol/L — the figure to use when converting between weight-percent, molarity and the dilution needed for a working solution.
Is nitric acid an oxidiser as well as a corrosive, and how is it classified for transport?
Yes. At 65–70 % it travels as UN 2031 (nitric acid, other than red fuming), hazard class 8 corrosive with a 5.1 oxidiser subsidiary risk, packing group II. The oxidising character is why it must be kept away from organic materials, reducing agents and combustibles, and why spills are neutralised with an alkali such as soda ash rather than absorbed onto sawdust or rags.
Nitric acid or hydrochloric acid — which is used for pickling?
Hydrochloric acid pickles carbon steel before galvanizing and coating because it dissolves iron scale quickly and cheaply. Nitric acid is used on stainless steel — alone for passivation and descaling, mixed with hydrofluoric acid for pickling mill scale — because its oxidising action rebuilds the chromium-oxide passive film instead of attacking the alloy. Using HCl on stainless risks chloride pitting; using nitric acid on carbon steel is wasteful and aggressive.
Can nitric acid be delivered in bulk in Egypt, and what tank material is needed?
Yes — 68–70 % nitric acid is delivered by bulk tanker as well as in 200 L drums and 1,000 L IBCs, each with a certificate of analysis. Receiving tanks are stainless steel (304L or 316L) or HDPE for smaller volumes, vented, bunded and sited away from organics and bases; mild steel, copper alloys and most plastics other than HDPE and PTFE are unsuitable. Our team can advise on tank and pipework materials before the first delivery.
Is nitric acid the same as aqua fortis (maa el-nar)?
Yes — aqua fortis, known across the Egyptian trade as maa el-nar (ماء النار), is the traditional commercial name for nitric acid (HNO₃), long familiar to jewellers and metal workshops. CHIMI ART supplies the technical grade at 68-70% concentration — stronger and more consistent than the diluted aqua fortis sold in small trade quantities — with a certificate of analysis for every delivery.
Is nitric acid used in agriculture and fertilizers?
Yes — nitric acid is the feedstock for nitrate fertilizers such as ammonium nitrate and calcium nitrate, and diluted solutions are dosed in drip-irrigation (fertigation) systems to lower irrigation-water pH and dissolve the carbonate scale that blocks emitters. The 68-70% grade we supply is industrial technical grade: for any agricultural use it must be diluted and dosed under a qualified agronomist's guidance.
Where can I buy nitric acid in Egypt?
CHIMI ART Industries, an Egyptian chemical manufacturer operating since 1977, supplies technical-grade nitric acid 68-70% from local stock in 200 L drums, 1,000 L IBCs and bulk tankers, delivered across Egypt with a certificate of analysis and full technical documentation (TDS/SDS). Request a quote on this page and our team responds within 24 business hours.
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