Ammonium nitrate (NH4NO3) is a chemical compound. It can be used as a fertilizer or an explosive. It is highly soluble in water and hygroscopic.
| IUPAC name | Ammonium nitrate |
| Molecular formula | NH4NO3 |
| CAS number | 6484-52-2 |
| Synonyms | Nitric acid ammonium salt, Ammonium nitrate (AN), Ammonium nitratum, Nitram, Nitramon |
| InChI | InChI=1S/NO3.H3N/c2-1(3)4;/h;1H3/q-1;/p+1 |
Ammonium Nitrate Properties
Ammonium Nitrate Formula
Ammonium nitrate is a chemical compound with the formula NH4NO3. It consists of two ions: ammonium (NH4+) and nitrate (NO3-), which are held together by an ionic bond2. It is a white crystalline powder that is readily soluble in water.
Ammonium Nitrate Molar Mass
The molar mass of NH4NO3 is 80.043 g/mol. It can be calculated by adding the molar masses of its constituent elements: nitrogen, hydrogen, and oxygen. The molar mass of nitrogen is 14.0067 g/mol, the molar mass of hydrogen is 1.00784 g/mol, and the molar mass of oxygen is 15.9999 g/mol.
The molar mass of NH4NO3 = 2 x molar mass of nitrogen + 4 x molar mass of hydrogen + 3 x molar mass of oxygen
The molar mass of NH4NO3 = 28.0134 g/mol + 4.03136 g/mol + 47.9997 g/mol
The molar mass of NH4NO3 = 80.043 g/mol
Ammonium Nitrate Boiling Point
NH4NO3 does not have a definite boiling point. It decomposes at high temperatures, releasing gases such as nitrogen, oxygen, and water vapor. The decomposition temperature of NH4NO3 varies depending on the purity, humidity, and presence of impurities or additives. The decomposition temperature of pure NH4NO3 is about 210 °C or 483 K.
Ammonium Nitrate Melting Point
The melting point of NH4NO3 is 169.6 °C or 442.8 K. It undergoes a phase transition from a rhombohedral crystal structure to a cubic crystal structure at this temperature. It can also form a eutectic mixture with water, which has a lower melting point of about -16 °C or 257 K.
Ammonium Nitrate Density g/ml
The density of NH4NO3 is 1.725 g/ml or 1725 kg/m3 at room temperature and pressure. It is denser than water, which has a density of about 1 g/ml or 1000 kg/m3 at the same conditions. The density of NH4NO3 decreases as the temperature increases, due to thermal expansion.
Ammonium Nitrate Molecular Weight
The molecular weight of NH4NO3 is the same as its molar mass, which is 80.043 g/mol. The molecular weight is the mass of one mole or 6.022 x 10^(23) molecules of NH4NO3. The molecular weight can also be expressed in atomic mass units (amu), which are defined as one-twelfth of the mass of a carbon-12 atom.
The molecular weight of NH4NO3 in amu is 80.043 x (1/12) x (10^(23)) amu
The molecular weight of NH4NO3 in amu is about 6.669 x 10^(23) amu
Ammonium Nitrate Structure
NH4NO3 has a simple ionic structure, consisting of positively charged ammonium ions and negatively charged nitrate ions. The ammonium ion has a tetrahedral shape, with four hydrogen atoms bonded to a central nitrogen atom by covalent bonds.
NH4+
H
|
H-N-H
|
H
The nitrate ion has a trigonal planar shape, with three oxygen atoms bonded to a central nitrogen atom by covalent bonds, one of which is a double bond.
NO3-
O
||
O
Ammonium Nitrate Solubility
NH4NO3 solubility refers to how much of this compound dissolves in water or other solvents. NH4NO3 is highly soluble in water and its solubility increases with temperature. For example, at 20 °C, 150 g of NH4NO3 can dissolve in 100 ml of water, but at 100 °C, 1024 g can dissolve in the same amount of water. NH4NO3 also dissolves in methanol, ethanol, and acetone, but not in diethyl ether or chloroform. The solubility of NH4NO3 depends on the presence of other substances, such as acids, bases, salts, or organic compounds. Some of these substances can affect the stability of NH4NO3 and cause it to decompose or explode.
| Appearance | White crystalline solid |
| Specific gravity | 1.725 |
| Color | White or grey |
| Odor | Odorless |
| Molar mass | 80.043 g/mol |
| Density | 1.725 g/ml or 1725 kg/m3 |
| Melting point | 169.6 °C or 442.8 K |
| Boiling point | Approx. 210 °C or 483 K (decomposes) |
| Flash point | Non-flammable |
| Water solubility | Endothermic, 118 g/100 ml (0 °C), 150 g/100 ml (20 °C), 297 g/100 ml (40 °C), 410 g/100 ml (60 °C), 576 g/100 ml (80 °C), 1024 g/100 ml (100 °C) |
| Solubility | Soluble in water, methanol, ethanol, acetone; insoluble in diethyl ether, chloroform |
| Vapour pressure | Negligible at room temperature |
| Vapour density | Not applicable (solid) |
| pKa | 9.25 (for NH4+) |
| pH | 5.0-6.0 (10% aqueous solution) |
Ammonium Nitrate Safety and Hazards
NH4NO3 safety and hazards are important to know for anyone who handles or stores this chemical compound. NH4NO3 is an oxidizer that can intensify fire and cause explosions if mixed with combustible materials or exposed to heat, shock, or contamination. NH4NO3 can also release toxic gases such as nitrogen oxides and ammonia when decomposed. Therefore, people should follow these safety precautions when dealing with NH4NO3:
- Store it in a cool, dry, and well-ventilated place away from fire sources, organic substances, acids, metals, and other incompatible materials.
- Wear protective clothing, gloves, eye, and face protection when handling it.
- Avoid creating dust and use proper ventilation when transferring it.
- Wash hands and face thoroughly after handling it.
- Do not ingest or inhale it and seek medical attention if exposed.
- Inform local emergency responders about the presence of NH4NO3 in the facility and have an emergency response plan ready.
| Hazard symbols | O (oxidizing agent), Xi (irritant) |
| Safety description | S17 (keep away from combustible material), S26 (in case of contact with eyes, rinse immediately with plenty of water and seek medical advice), S36/37/39 (wear suitable protective clothing, gloves and eye/face protection), S42 (during fumigation/spraying wear suitable respiratory equipment) |
| UN IDs | S17 (keep away from combustible material), S26 (in case of contact with eyes, rinse immediately with plenty of water and seek medical advice), S36/37/39 (wear suitable protective clothing, gloves, and eye/face protection), S42 (during fumigation/spraying wear suitable respiratory equipment) |
| HS code | 3102.30 (ammonium nitrate, whether or not in aqueous solution) |
| Hazard class | 5.1 (oxidizing agent) |
| Packing group | III (low danger) |
| Toxicity | LD50 (oral, rat) = 2085-5300 mg/kg |
Ammonium Nitrate Synthesis Methods
To produce this chemical compound, widely used as a fertilizer and an explosive, chemists use various methods of NH4NO3 synthesis. There are different methods to synthesize NH4NO3, but the most common ones are:
- The Haber–Bosch and Ostwald process: This method involves reacting nitrogen and hydrogen gases to form ammonia, and then oxidizing ammonia with air to form nitric acid. To form NH4NO3, they neutralize the ammonia and nitric acid. This method requires high temperature, pressure, and energy, and emits a lot of carbon dioxide.
- The metathesis reaction: This method involves reacting a soluble ammonium salt with a soluble nitrate salt to form NH4NO3 and another salt. For example, ammonium sulfate and barium nitrate can react to form NH4NO3 and barium sulfate. This method is simple and does not require high temperature or pressure, but it produces a by-product that may need to be separated or disposed of.
- The plasma process: This method involves using a low-temperature and low-pressure plasma to fix nitrogen from the air into the soil, forming NH4NO3 directly in the soil. This method does not require hydrogen gas or catalysts and does not emit carbon dioxide. It can also enrich the soil with nitrogen content and enhance plant growth.
Ammonium Nitrate Uses
Here are some uses of NH4NO3:
- Fertilizer: NH4NO3 is a common source of nitrogen for plants, as it contains about 33.5% nitrogen, all of which are available for plant uptake. Manufacturers coat white or grey pellets of ammonium carbonate with clay to prevent them from caking and absorbing moisture. They can apply it as a solid or a solution because water dissolves it easily.
- Explosive: NH4NO3 is an oxidizing agent that can enhance the detonation of other explosives, such as nitroglycerin, TNT, RDX, or aluminum powder. A widely used industrial explosive that accounts for 80% of explosives used in North America has ANFO (NH4NO3 and fuel oil) as its main ingredient. It requires a strong initiator to detonate it when used in improvised explosive devices, but industrial applications can also use it.
- Pyrotechnics: Fireworks can use NH4NO3 to create various effects, such as smoke, sparks, stars, and flashes. Cold packs can also use it, which produces an endothermic reaction when mixed with water.
- Other uses: Used as a precursor by nitrous oxide (laughing gas), an anesthetic, and a propellant. Nitrogen oxides can use as an absorbent, yeast, and antibiotics can use as nutrients, and freezing mixtures can use as a component.
Questions:
Q: Where does ammonium nitrate fertilizer come from?
A: NH4NO3 fertilizer is a synthetic product that comes from the reaction of ammonia and nitric acid. Ammonia is obtained from natural gas or other sources, and nitric acid is produced by oxidizing ammonia with air. NH4NO3 fertilizer can also be produced by using a plasma process that fixes nitrogen from the air into the soil.
Q: What is ammonium nitrate?
A: NH4NO3 is a chemical compound with the formula NH4NO3. It is a white crystalline salt that consists of ammonium and nitrate ions. It is highly soluble in water and hygroscopic as a solid, although it does not form hydrates.
Q: What is ammonium nitrate used for?
A: NH4NO3 is mainly used for two purposes: as a fertilizer and as an explosive. As a fertilizer, it provides nitrogen to plants, which is essential for their growth and metabolism. As an explosive, it acts as an oxidizer that enhances the detonation of other explosives, such as ANFO (NH4NO3 and fuel oil)1. It can also be used for other purposes, such as making nitrous oxide (laughing gas), cold packs, fireworks, and yeast nutrients.
Q: What is the molecular formula for ammonium nitrate?
A: The molecular formula for ammonium nitrate is NH4NO3. It has a molar mass of 80.043 g/mol and contains 35% nitrogen by mass.
Q: What is ammonium nitrate fertilizer made of?
A: NH4NO3 fertilizer is made of NH4NO3 and sometimes other additives, such as clay, anti-caking agents, or stabilizers. The commercial grade contains about 33.5% nitrogen, all of which is in forms available for plant uptake.
Q: Is ammonium nitrate an acid or base?
A: NH4NO3 is neither an acid nor a base, but a salt. It can dissociate in water into ammonium and nitrate ions, which can act as weak acids or bases depending on the pH of the solution. The ammonium ion has a pKa of 9.25, meaning it can donate a proton and act as an acid in basic solutions. The nitrate ion has no pKa, meaning it cannot donate or accept protons, but it can act as a base by forming nitric acid with hydronium ions in acidic solutions.
Q: Ammonium nitrate explosion?
A: An NH4NO3 explosion is a violent chemical reaction that occurs when NH4NO3 decomposes rapidly and releases large amounts of gases, such as nitrogen, oxygen, and water vapor. The decomposition can be triggered by heat, shock, friction, contamination, or confinement. An NH4NO3 explosion can cause severe damage to buildings, people, and the environment. Some examples of NH4NO3 explosions are the Texas City disaster in 1947, the Oppau explosion in 1921, the Tianjin explosion in 2015, and the Beirut explosion in 2020.
Q: How to buy ammonium nitrate?
A: Buying NH4NO3 may require a license or a permit depending on the country or region where you live. This is because NH4NO3 can be used to make explosives or improvised explosive devices that can pose a threat to public safety. You may also need to provide your identity, address, contact details, and the intended use of the product when buying NH4NO3. One can buy NH4NO3 from authorized suppliers or distributors that comply with local regulations and standards. You should also follow the proper storage and handling guidelines to prevent accidents or misuse of NH4NO3.