Concentrated Nitric Acid (HNO₃) is a strong oxidizing agent and one of the most widely used industrial chemicals. It is a colorless to yellowish liquid that is highly corrosive and has a strong pungent odor. Nitric acid is primarily used in the production of fertilizers, particularly ammonium nitrate, and for various other industrial processes like metal etching, explosives production, and chemical synthesis.
When concentrated, nitric acid typically contains around 68-70% nitric acid by weight, with the remainder being water. It is a powerful acid and oxidizer that is often employed in reactions requiring the generation of nitronium ions (NO₂⁺), an essential species for nitration reactions.
Properties of Concentrated Nitric Acid:
- Chemical Formula: HNO₃
- Molar Mass: 63.01 g/mol
- Appearance: Colorless or pale yellow liquid. The yellow color develops over time due to the presence of nitrogen dioxide (NO₂), which forms in the presence of air.
- Odor: Strong, pungent, acrid odor, similar to that of oxidizing agents.
- Density: Approximately 1.41 g/cm³ at 20°C.
- Boiling Point: 83°C (181.4°F) for 68% concentration. It decomposes at higher temperatures, releasing toxic gases like nitrogen oxides (NOx).
- Melting Point: Nitric acid freezes at -42°C (-44°F), which makes it liquid at room temperature.
- pH: Highly acidic, usually below 1 when concentrated, making it extremely corrosive.
- Viscosity: Relatively low compared to other acids, which facilitates its use in liquid form in various industrial processes.
Key Uses of Concentrated Nitric Acid:
- Chemical Synthesis: Used in the production of fertilizers, explosives, and organic compounds.
- Metal Industry: For metal passivation and to produce nitrates.
- Rocket Propellants: As an oxidizer in rocket fuel.
- Electronics: Used in etching and cleaning electronic components.