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Heading 2806 : Hydrogen chloride (hydrochloric acid); chlorosulphuric acid.
(A) HYDROGEN CHLORIDE (HYDROCHLORIC ACID)
Hydrogen chloride (HCl) is a colourless fuming gas with a suffocating odour, obtained by the action of hydrogen (or of water and coke) on chlorine, or by the action of sulphuric acid on sodium chloride.
It is easily liquefied under pressure and very soluble in water. It is presented under pressure in liquid form in steel cylinders. It is also presented in concentrated aqueous solutions (usually 28 to 38 %) (hydrochloric acid, muriatic acid, spirits of salt) in glass or earthenware containers or in rubber‑lined tank wagons or tank trucks. These pungent‑smelling solutions are yellowish if the product contains impurities (ferric chloride, arsenic, sulphur dioxide, sulphuric acid), and colourless if pure. The concentrated solutions give off white fumes in damp air.
Hydrochloric acid has many uses, e.g., pickling iron, zinc or other metals, extracting gelatin from bones, purifying animal black, preparing metal chlorides, etc. Hydrogen chloride gas is often employed in organic syntheses (e.g., in the manufacture of chloroprene, vinyl chloride, artificial camphor, rubber hydrochloride). (B) CHLOROSULPHURIC ACID (CHLOROSULPHONIC ACID)
Chlorosulphuric acid, commercially designated as chlorosulphonic acid ("sulphuric chlorohydrin") and having the chemical formula ClSO2OH, results from the dry combination of hydrogen chloride with sulphur trioxide or oleum.
It is a highly corrosive, colourless or brownish liquid with an irritating odour; it fumes in a humid atmosphere and decomposes on contact with water or if heated.
It is used in organic syntheses (manufacture of saccharin, thioindigo, indigosols, etc.).
The heading excludes hypochlorous, chloric or perchloric acids (heading 28.11). The heading also excludes sulphur dichloride dioxide (sulphuryl chloride) (heading 28.12), which is sometimes erroneously referred to as "chlorosulphuric acid".
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clhs@clhs.co.kr 
070-4214-8300