Ammonium chloride is an inorganic chemical compound with the chemical formula NH4Cl, also written as [NH4]Cl. It is an ammonium salt of hydrogen chloride. It consists of ammonium cations [NH4]+ and chloride anions Cl−. It is a white crystalline salt that is highly soluble in water. Solutions of ammonium chloride are mildly acidic. In its naturally occurring mineralogic form, it is known as salammoniac. The mineral is commonly formed on burning coal dumps from condensation of coal-derived gases. It is also found around some types of volcanic vents. It is mainly used as fertilizer and a flavouring agent in some types of liquorice. It is a product of the reaction of hydrochloric acid and ammonia.

Nitrogen is a chemical element; it has symbol N and atomic number 7. Nitrogen is a nonmetal and the lightest member of group 15 of the periodic table, often called the pnictogens. It is a common element in the universe, estimated at seventh in total abundance in the Milky Way and the Solar System. At standard temperature and pressure, two atoms of the element bond to form N2, a colorless and odorless diatomic gas. N2 forms about 78% of Earth's atmosphere, making it the most abundant uncombined element in air. Because of the volatility of nitrogen compounds, nitrogen is relatively rare in the solid parts of the Earth.