Nitric acid (HNO3) is a strong and highly reactive inorganic acid. It is used in fertilizers, explosives, and the dyeing and printing textile industry. It also forms nitrates, which are important in biological processes and combustion reactions.
| IUPAC Name | Nitric acid |
| Molecular Formula | HNO3 |
| CAS number | 7697-37-2 |
| Synonyms | Aqua fortis, Spirit of nitre, Nitrous acid |
| InChI | InChI=1S/HNO3/c2-1(3)4 |
Nitric Acid Properties
Nitric Acid Molar Mass
The molar mass of nitric acid is 63.01 g/mol. It is the amount of substance that contains the same number of entities (such as atoms, molecules, or ions) as there are in 12 grams of pure carbon-12.
Nitric Acid Formula
The chemical formula of nitric acid is HNO<sub>3</sub>. It represents the number and type of atoms in the molecule. The formula can be used to predict its physical and chemical properties, such as boiling point, melting point, and density.
Nitric Acid Boiling Point
The boiling point of nitric acid is 83.0 °C (181.4 °F). It is the temperature at which a substance changes its state from liquid to gas at a given pressure. Nitric acid is a highly reactive and volatile substance, and the boiling point helps to determine the conditions under which it should be handled and stored.
Nitric Acid Melting Point
The melting point of nitric acid is -41.5 °C (-42.7 °F). It is the temperature at which a solid substance changes its state to liquid. The low melting point of nitric acid makes it easy to handle in its liquid form.
Nitric Acid Density g/ml
The density of nitric acid is 1.51 g/mL. It is a measure of the amount of mass per unit volume of a substance. The density of nitric acid can help determine its storage and handling requirements, as well as its potential for reacting with other substances.
Nitric Acid Molecular Weight
The molecular weight of nitric acid is 63.01 g/mol. It is the sum of the atomic weights of the individual atoms in the molecule. The molecular weight of nitric acid is an important factor in determining its physical and chemical properties.
Nitric Acid Structure
Nitric acid is a colorless, highly reactive, and volatile liquid. Its molecular structure consists of a nitrogen atom, a hydrogen atom, and three oxygen atoms, forming the chemical formula HNO3. The oxygen atoms are arranged in a trigonal planar arrangement around the nitrogen atom.
| Appearance | Colorless liquid |
| Specific Gravity | 1.51 g/mL |
| Color | Colorless |
| Odor | Pungent, acrid odor |
| Molar Mass | 63.01 g/mol |
| Density | 1.51 g/mL |
| Melting Point | -41.5 °C (-42.7 °F) |
| Boiling Point | 83.0 °C (181.4 °F) |
| Flash Point | Not applicable |
| Water Solubility | Miscible |
| Solubility | Soluble in alcohol, ether, and other polar solvents |
| Vapor Pressure | High at room temperature |
| Vapor Density | 1.48 (air = 1) |
| pKa | -1.3 |
| pH | 1 (10% solution) |
Note: The flash point of nitric acid is not applicable as it is a liquid. The pH of a 10% solution of nitric acid is 1, indicating it is a strong acid. The pKa is the negative logarithm of the acid dissociation constant, which is a measure of the strength of an acid in solution.
Nitric Acid Safety and Hazards
Nitric acid is a highly reactive and corrosive substance that can cause severe injury or death if not handled properly. It can cause burns, eye damage, and respiratory irritation. Proper protective equipment, such as gloves and goggles, should be worn when handling nitric acid. Storage areas should be well-ventilated, and spills should be promptly cleaned up to avoid releases of toxic fumes. In case of skin or eye contact, flush the affected area with water for at least 20 minutes and seek medical attention immediately.
| Hazard Symbols | Dangerous for the Environment, Oxidizing, Harmful, Irritant |
| Safety Description | S2 – Keep out of reach of children. S23 – Do not breathe fumes. S24/25 – Avoid contact with skin and eyes. S26 – In case of contact with eyes, rinse immediately with plenty of water and seek medical advice. |
| UN IDs | UN 2031 |
| HS Code | 2811.90.90 |
| Hazard Class | 8 |
| Packing Group | III |
| Toxicity | Highly toxic by ingestion and inhalation. Can cause severe burns and eye damage, as well as respiratory irritation. |
Nitric Acid Synthesis Methods
Nitric acid can be synthesized through several methods, including:
- Ostwald Process: This method involves the oxidation of ammonia with air to form nitric oxide, which is then oxidized to nitric acid.
- Nitration of Toluene: This method involves the nitration of toluene to form nitro-toluene, which is then oxidized to form nitric acid.
- Thermal Decomposition of Ammonium Nitrate: This method involves heating ammonium nitrate to produce nitric oxide, which is then oxidized to form nitric acid.
- Direct Oxidation of Ammonia: This method involves the direct oxidation of ammonia with oxygen to produce nitric acid.
- Electrolysis of Sodium Nitrate: This method involves the electrolysis of sodium nitrate to produce nitric acid.
These methods vary in terms of efficiency, cost, and environmental impact, and the choice of method depends on the desired end use and production scale.
Nitric Acid Uses
Nitric acid has a wide range of uses in various industries, including:
- Fertilizers: Nitric acid is used in the production of nitrogen fertilizers, such as ammonium nitrate and nitric acid salts.
- Pharmaceuticals: Nitric acid is used as a reagent in the production of pharmaceuticals and other chemical intermediates.
- Explosives: Nitric acid is used in the production of explosives, such as dynamite and nitrocellulose.
- Metal Processing: Nitric acid is used for pickling, cleaning, and etching metals, including steel, copper, and aluminum.
- Dyeing and Printing: Used as a mordant in dyeing and printing processes.
- Water Treatment: Nitric acid is used in water treatment to control pH levels and remove impurities.
- Research and Development: Nitric acid is used as a laboratory reagent for various chemical reactions and analysis.
Overall, nitric acid has a versatile range of applications due to its acidic and oxidizing properties, making it a crucial chemical in various industrial processes.
Questions:
Is nitric acid a strong acid or a weak acid?
Yes, nitric acid (HNO3) is considered a strong acid. Strong acids dissociate completely in water to produce hydrogen ions (H+), meaning that they ionize completely. In contrast, weak acids only partially ionize in water, meaning that they do not dissociate completely.
In a solution of nitric acid, nearly all of the molecules will have donated a hydrogen ion, making it a strong proton donor. As a result, nitric acid has a high concentration of hydrogen ions and a low pH, typically around 1-2. The strength of an acid is determined by its ability to donate hydrogen ions and nitric acid is one of the strongest acids in the list of strong acids.
Note that nitric acid (HNO3) exerts a strong oxidizing effect and poses a threat of severe burns and chemical reactions. Handle nitric acid with caution and wear proper protective equipment.