Hydrochloric acid (hydrogen chloride) is an aqueous solution of hydrochloric gas (HCl). The product is widely used in the metal industry for pickling metals and in the chemical industry for acidification, dissolving and neutralizing reactions.
Hydrochloric acid is also used for the treatment and the production of dyes and synthetic rubber. It is used for pH control and regeneration of ion exchangers, as well as in the sugar industry. Remains of hydrochloric acid are found in precipitation and flotation agents.
Hydrochloric acid has a pungent odor and is highly corrosive in concentrated form. Because of the high solubility in water the gas emits smoke in moist air.
Concentrated hydrochloric acid mixed with concentrated nitric acid gives aqua regia, one of very few solutions that can oxidize pure gold and platinum.