Ammonium Chloride is a nitrogen-based inorganic compound widely used as a nitrogen fertilizer, particularly in alkaline and neutral soils. It appears as a white crystalline solid or granules and contains approximately 25–26% nitrogen (N), an essential nutrient for plant growth.
In agriculture, ammonium chloride supplies nitrogen in ammoniacal form, promoting vigorous vegetative growth and improved crop yields. Beyond fertilizers, it is extensively used in industrial, pharmaceutical, food, and metallurgical applications.
Chemical Composition
| Component | Typical Content |
|---|---|
| Nitrogen (N) | ~26.0% |
| Chloride (Cl) | ~66.0% |
| Hydrogen (H) | ~7.5% |
| Chemical Formula | NH₄Cl |
| Molecular Weight | 53.49 g/mol |
| Crystal System | Cubic (Isometric) |
Key Physical Properties
| Property | Value |
|---|---|
| Physical State | White crystalline solid |
| Odor | Odorless |
| Density | ~1.53 g/cm³ |
| Melting Point | ~338 °C (sublimes) |
| Solubility in Water | Very high |
| pH (5% solution) | ~4.5–6.0 |
| Hygroscopicity | Moderate |
📌 Sublimes instead of melting under normal pressure
📌 Acidic nature influences material compatibility
Key Mechanical Properties
| Property | Behavior |
|---|---|
| Hardness | Low |
| Brittleness | High |
| Compressibility | Moderate |
| Abrasion Resistance | Low |
| Flowability | Moderate |
| Caking Tendency | Moderate |
Strengthening & Metallurgical Behavior
Ammonium chloride has no mechanical strengthening role and functions as a chemical facilitator in metallurgy.
✔ Acts as a flux in soldering and brazing
✔ Removes metal oxides (Cu, Zn, Sn, Fe)
✔ Improves solder wetting and surface activation
Thermal decomposition releases ammonia and hydrogen chloride, where HCl cleans oxide layers and NH₃ creates a limited reducing atmosphere.
Key Characteristics
✔ Highly water-soluble
✔ Acidic salt (pH-lowering effect)
✔ Sublimes cleanly without residue
✔ Effective oxide remover
✔ Stable under ambient conditions
✔ High ionic conductivity in solution
Refining & Processing
Produced by neutralization of ammonia with hydrochloric acid, as a by-product of the Solvay process, or via ammonium sulfate conversion routes.
✔ Easily crystallized from aqueous solutions
✔ Purity controlled through recrystallization
✔ Granulated or milled to required particle size
✔ Dried at low temperature to avoid decomposition
Available Forms
Powder (technical / industrial)
Crystals (coarse / fine)
Granules (fertilizer grade)
Tablets and blocks (flux use)
Aqueous solutions
Food and pharmaceutical grades
Applications
Agriculture: Nitrogen fertilizer, soil acidifier, chloride-tolerant crops
Metallurgy: Flux for soldering and brazing, galvanizing preparation
Electronics: Battery electrolytes, conductivity enhancement
Chemical: Buffer solutions, pH control, intermediates
Food & Pharma: Dough conditioner, expectorant, tablet formulations
Advantages
✔ Dual nitrogen and chloride supply
✔ Excellent oxide removal capability
✔ High solubility and reactivity
✔ Economical and widely available
✔ Multi-industry versatility
Comparison with Other Ammonium Salts
| Feature | NH₄Cl | (NH₄)₂SO₄ | NH₄NO₃ |
|---|---|---|---|
| Nitrogen % | 26% | 21% | 34% |
| Acidity | Moderate | High | Low |
| Chloride | High | None | None |
| Metallurgical Use | Excellent | Limited | Not suitable |
Limitations
Chloride sensitivity in some crops
Corrosive to certain metals
Moisture-sensitive storage
Not suitable for chloride-restricted applications
Dust control required in powder handling