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Nitric acid is a highly corrosive and strong oxidizing agent that is widely used in various industries for its versatile properties. It is available in two main forms: weak nitric acid and concentrated nitric acid.
Weak nitric acid, typically with a concentration of around 68-72% by weight, is commonly used in applications such as pickling and cleaning metals, etching printed circuit boards, and producing ammonium nitrate. It is milder in nature compared to concentrated nitric acid and is suitable for processes that require controlled and less aggressive reactions.
Concentrated nitric acid, with a minimum concentration of 98.5% by weight, is known as fuming nitric acid. It is a highly potent and reactive form of nitric acid used for various purposes, including nitrations, oxidations, and etching processes. Concentrated nitric acid is characterized by its yellowish color and pungent odor.
| Property | Concentrated Nitric Acid | Weak Nitric Acid |
|---|---|---|
| HNO3 Concentration | 98.5% by weight minimum | 61.5 ± 0.5% by weight (68%, 72%) |
| Nitrous Oxide as HNO2 | 500 ppm maximum | 500 ppm maximum |
| Chloride as Cl | 10 ppm maximum | 10 ppm maximum |
| Sulphate as H2SO4 | – | 50 ppm maximum |
| Arsenic as As | – | 2 ppm maximum |
| Residue on Ignition | 500 ppm maximum | 100 ppm maximum |
| Heavy Metal as Pb | To pass the test | To pass the test |
| Specific Gravity | 1.5 at 25°C | 1.368 at 25°C |
| CAS Number | 7697-37-2 | 7697-37-2 |
| UN Number | 2031 | 2031 |