Nitric Acid
Definition and meaning of Nitric Acid in chemistry.
Nitric acid is a highly corrosive mineral acid with the chemical formula HNO3. It is a strong acid and a powerful oxidizing agent. Pure nitric acid is a colorless liquid, but older samples often turn yellow.
In more detail
Factories manufacture nitric acid on a large scale using the Ostwald process. This industrial process uses a catalyst to react ammonia gas with oxygen. A catalyst is a substance that speeds up a reaction without being consumed.
The initial reaction produces nitric oxide gas and water vapor. Next, the nitric oxide reacts with additional oxygen to form nitrogen dioxide. Water then absorbs the nitrogen dioxide gas to create liquid nitric acid.
The agriculture industry consumes the vast majority of the world's nitric acid. They use it to produce crop fertilizers like ammonium nitrate. Chemical companies also use nitric acid to manufacture powerful military explosives.
These explosives include trinitrotoluene, nitroglycerin, and a compound called RDX. Furthermore, nitric acid serves as a key precursor for making nylon and polyurethanes. Nitric acid acts as a powerful oxidizing agent in chemical reactions.
This means it easily strips electrons away from other reactive substances. The acid reacts violently with many nonmetals and most transition metals. It easily dissolves valuable precious metals like silver and solid copper.
However, pure nitric acid cannot dissolve solid gold on its own. Chemists mix concentrated nitric acid with hydrochloric acid to make aqua regia. This fuming mixture generates nitrosyl chloride and highly reactive elemental chlorine.
Aqua regia possesses the unique ability to dissolve gold and platinum. Scientists must handle concentrated nitric acid with extreme care and safety gear. Direct contact with the skin causes severe and immediate chemical burns.
The acid rapidly reacts with keratin proteins found in human skin. This chemical reaction leaves a distinct yellow stain on the damaged tissue.
Key facts
| Field | Inorganic Chemistry |
|---|---|
| Formula | HNO3 |
| Molar mass | 63.012 g/mol |
| Density | 1.51 g/cm³ |
| Boiling point | 83 °C |
When you place a piece of copper in concentrated nitric acid, it rapidly dissolves. This vigorous reaction produces a blue-green solution of copper(II) nitrate. It also releases a highly toxic, brown gas called nitrogen dioxide.
Frequently asked questions
What is aqua regia?
Aqua regia is a fuming mixture of nitric acid and hydrochloric acid. Chemists usually mix them in a one to three molar ratio. This powerful liquid can dissolve noble metals like gold.
Why does concentrated nitric acid turn yellow over time?
Nitric acid slowly decomposes when exposed to room light and ambient heat. This breakdown releases nitrogen dioxide gas into the liquid. The dissolved gas gives the acid a yellow or brown color.
Related terms
Sources & references
See our sources and editorial standards.