Ferric chloride is a chemical compound with the formula FeCl3. It appears as a dark brown or yellowish solid and is highly soluble in water. Ferric chloride is commonly used in water treatment processes to remove impurities and as a coagulant in the production of drinking water. In addition to its use in water purification, ferric chloride is also employed in the manufacturing of printed circuit boards and as a catalyst in various chemical reactions. It can be produced by reacting iron with chlorine gas or by dissolving iron(III) oxide in hydrochloric acid.