Hydrogen chloride. Molecular model of hydrogen chloride (hydrochloric acid). The white sphere represent an atom of hydrogen. The green sphere represents an atom of chlorine. The two atoms are held together by a single bond. Hydrogen chloride is a colourless gas with an irritating smell. It is highly soluble and dissolves to form hydrochloric acid. Hydrogen chloride is produced during the chlorination of hydrocarbons, by burning hydrogen in chlorine and in the reaction between sodium chloride and sulphuric acid. Gaseous hydrogen chloride and hydrochloric acid are widely used in the organic chemistry industry.