Definition
Salammoniac, also known as ammonium chloride, is an inorganic compound with the chemical formula NH₄Cl. It appears as a white crystalline solid that is highly soluble in water and has a faint, saline taste.
Overview
Salammoniac occurs naturally as the mineral sal ammoniac, typically forming in volcanic fumaroles and as a sublimation product in coal mines. Industrially, it is produced by the reaction of hydrogen chloride gas with aqueous ammonia or by the thermal decomposition of ammonium sulfate. The compound has been employed historically in medicine as an expectorant, in the metalworking industry as a flux for soldering and brazing, and in food processing as a flavoring agent (e.g., in licorice). It also serves as a component of electrolyte solutions and as a source of nitrogen in certain fertilizer formulations.
Etymology/Origin
The name “sal ammoniac” derives from the Latin sal ammoniacus, meaning “salt of Ammon.” This designation references the ancient temple of the Egyptian god Amun (Ammon) at the oasis of Siwa in the Libyan Desert, where the mineral was reportedly first observed as a sublimated deposit from volcanic gases. The modern spelling “salammoniac” reflects the concatenation of the two words but retains the same origin.
Characteristics
| Property | Value |
|---|---|
| Chemical formula | NH₄Cl |
| Molar mass | 53.49 g mol⁻¹ |
| Appearance | White crystalline solid |
| Density | 1.527 g cm⁻³ (20 °C) |
| Melting point | 338 °C (decomposes to NH₃ and HCl) |
| Boiling point | Decomposes before boiling; sublimates at 340 °C |
| Solubility in water | 29.4 g · 100 mL⁻¹ at 0 °C; 74.5 g · 100 mL⁻¹ at 100 °C |
| pH of a 1 % aqueous solution | Approximately 5.5 (slightly acidic) |
| Crystal system | Cubic (isometric) |
Salammoniac is hygroscopic, readily absorbing moisture from the atmosphere. Upon heating, it undergoes endothermic decomposition, releasing ammonia (NH₃) and hydrogen chloride (HCl) gases. The compound is non‑flammable but can release corrosive gases when heated in confined spaces.
Related Topics
- Ammonium chloride – the modern chemical name for salammoniac.
- Ammonia (NH₃) – a basic nitrogenous compound that reacts with hydrogen chloride to form NH₄Cl.
- Hydrogen chloride (HCl) – a gaseous acid that combines with ammonia to produce salammoniac.
- Flux (metalworking) – substances, including salammoniac, used to remove oxides during soldering and brazing.
- Salpeter (potassium nitrate) – another historically important mineral used in pyrotechnics and preservation.
References: Standard chemical handbooks, mineralogical surveys of volcanic fumaroles, and historic pharmaceutical compendia.