Ammonium chloride (abbreviated as NH₄Cl) is an inorganic compound with the chemical formula NH₄Cl. It is the ammonium salt of hydrochloric acid and is mostly a by-product of the alkali manufacturing industry. Ammonium chloride appears as small, white or slightly yellow, square or octahedral crystals, available in both powdered and granular forms. Granular ammonium chloride is less hygroscopic and easier to store, while powdered ammonium chloride is more commonly used as a base fertilizer for producing compound fertilizers.
Ammonium chloride is easily soluble in water and glycerol, slightly soluble in ethanol, and insoluble in benzene and ether. In dry air, it is prone to efflorescence and loss of crystal water, while in humid air, it undergoes hydrolysis leading to hydrochloric acid corrosion. All ammonium salts possess the general properties of bases, but ammonium chloride itself is an acidic substance. It is easily decomposed upon heating and reacts with acids to form ammonium salts. Upon intense burning, it can produce strongly irritating gases such as nitrogen oxides and ammonia. In the hot-dip galvanizing process, it is generally mixed with zinc chloride for use.
