7705-08-0 Usage
Health Hazard
Inhalation of dust may irritate nose and throat. Ingestion causes irritation of mouth and stomach. Dust irritates eyes. Prolonged contact with skin causes irritation and burns.
Production Methods
Iron(III) chloride forms passing chlorine gas over iron filings at 350°C:
2Fe + 3Cl2 → 2FeCl3
It also forms heating iron(III) oxide with HCl at elevated temperatures:
Fe2O3 + 6HCl → 2FeCl3 + 3H2O
The product may be sublimed in a stream of chlorine to give high purity grade iron(III) chloride.
The anhydrous chloride also may be made by heating the hexahydrate, FeCl3•6H2O, with thionyl chloride:
FeCl3•6H2O + 6SOCl2 → FeCl3 + 12HCl + SO2
General Description
Ferric chloride is an orange to brown-black solid. Ferric chloride is slightly soluble in water. Ferric chloride is noncombustible. When wet Ferric chloride is corrosive to aluminum and most metals. Pick up and remove spilled solid before adding water. Ferric chloride is used to treat sewage, industrial waste, to purify water, as an etching agent for engraving circuit boards, and in the manufacture of other chemicals.
Fire Hazard
Special Hazards of Combustion Products: Irritating hydrogen chloride fumes may form in fire.
Air & Water Reactions
Very hygroscopic. Slightly water soluble, where a 0.1M solution has a pH of 2.0.
Reactivity Profile
Alkali metal hydroxides, acids, anhydrous chlorides of iron, tin, and aluminum, pure oxides of iron and aluminum, and metallic potassium are some of the catalysts that may cause ethylene oxide to rearrange and polymerize, liberating heat, [J. Soc. Chem. Ind. 68:179(1949)]. Explosions occur , although infrequently, from the combination of ethylene oxide and alcohols or mercaptans, [Chem. Eng. News 20:1318(1942)]. Allyl chloride may polymerize violently under conditions involving an acid catalyst, such as sulfuric acid, Ferric chloride, aluminum chloride, Lewis acids, and Ziegler type catalysts (initiators), [Ventrone (1971)].
Uses
Iron(III) chloride occurs naturally as the mineral molysite. The compound is widely used to prepare a number of iron(III) salts. Also, it is applied in sewage and industrial waste treatment processes. It also is used in the manufacture of dyes, pigments and inks; as a chlorinating agent; and as a catalyst in chlorination reactions of aromatics.
Chemical Properties
Ferric chloride,FeCl3, is a brown crystalline solid and is soluble in water,alcohol,and glycerol. It is also known as anhydrous ferric chloride,ferric trichloride, Flores martis,and iron chloride. Ferric chloride is used as a coagulant for sewage and industrial wastes, as an oxidizing and chlorinating agent,as a disinfectant, in copper etching, and as amordant. In addition, this compound is employed in the ferric chloride test,which is used to assess the relative corrosion resistance of stainless and nickel-base alloys. The ferric chloride test has been shown to be an appropriate measure of the suitability of such alloys for service in paper mill bleach plants and seawater.
Physical properties
Dark brown hexagonal crystals; hygroscopic; density 2.898g/cm3; melts at 306°C; decomposes at 315°C; highly soluble in water (74.4g/100g water at 0°C); very soluble in alcohol, ether and acetone.
The hexahydrate is brownish-yellow crystalline mass; deliquesces; melts at 37°C; vaporizes around 280°C; highly soluble in water (92g/100g water at 20°C); very soluble in organic solvents such as ethanol, ether and acetone.
Purification Methods
Sublime it at 200o in an atmosphere of chlorine. It is an “iron-black” coloured powder with green irridescence. Store it in a weighing bottle inside a desiccator as it absorbs moisture from air to form the yellow hexahydrate (see next entry). [Tarr Inorg Synth III 191 1950, Pray Inorg Synth V 153 1957, Epperson Inorg Synth VII 163 1963.]
