A toxic, colorless, strongly acidic gas (HCl) that dissolves readily in water
to form hydrochloric acid.
In the troposphere, hydrochloric acid can be produced from the reaction of
nitric acid or sulfuric acid with sea-salt particles (NaCl). It is also
involved in the formation of ammonium chloride aerosol. HCl is also the most
abundant form of chlorine in an inorganic compound found in the stratosphere.
Produced there predominantly from the reaction of Cl atoms with methane and
molecular hydrogen, it acts as a temporary, relatively unreactive reservoir
species for chlorine.
