Aqueous solution of the gas hydrogen chloride (HCl), colorless or slightly yellowish, with a pungent odor and irritating. It is a strong acid, highly corrosive, used in cleaning and descaling for metal surface treatment, water treatment, pH adjustment in industrial processes, pickling of steel and in the production of chemical compounds. Their manipulation requires strict security measures due to their character corrosive and the release of vapors irritating to the respiratory tract.