Ammonium chloride (NH4Cl) is an inorganic chemical compound formed from the reaction of ammonia (NH3) with either gaseous hydrogen chloride (HCl) or hydrochloric acid in aqueous solution. Its primary production method is as a byproduct of the Solvay process, used in the manufacture of sodium carbonate. The overall reaction for its formation in this process is: CO2 + 2 NH3 + 2 NaCl + H2O → 2 NH4Cl + Na2CO3. This method not only yields ammonium chloride but also helps manage ammonia emissions in industrial operations. The direct synthesis from ammonia and hydrochloric acid is straightforward: NH3 + HCl → NH4Cl.

Upon heating, ammonium chloride does not truly sublime but rather undergoes reversible decomposition into ammonia and hydrogen chloride gas: NH4Cl ⇌ NH3 + HCl. This dissociation is a key characteristic of the compound. Additionally, it reacts with strong bases, such as sodium hydroxide, releasing ammonia gas: NH4Cl + NaOH → NH3 + NaCl + H2O. It also reacts with alkali-metal carbonates at higher temperatures. In aqueous solutions, ammonium chloride exhibits mild acidity, with a 5% solution typically having a pH between 4.6 and 6.0, indicating its nature as a salt of a weak base and a strong acid.

Physically, ammonium chloride is a white crystalline solid that is highly soluble in water. It is also soluble in liquid ammonia and methanol. Its properties, such as molar mass (53.49 g/mol), density (1.519 g/cm³), and a decomposition point of 338 °C, are well-documented. Understanding these fundamental chemical properties and production methods is crucial for its effective utilization across various industrial and scientific applications. Sourcing pure ammonium chloride ensures predictable behavior in chemical processes and product formulations, making it a reliable compound for diverse needs.