Iron III chloride hexahydrate on watch glass (FeCl3.6H2O) molar mass 270.295 g/mol Also known as Iron trichloride, Ferric chloride, Molysite, Flores martis Iron III chloride is an inorganic compound and is harmful, highly corrosive and acidic. Iron trichloride hexahydrate is a hydrate that is the hexahydrate form of iron trichloride. It has a role as an astringent and a Lewis acid. It is a hydrate, an inorganic chloride and an iron coordination entity. It contains an iron trichloride.