What is Ferric chloride Hexahydrate
Ferric chloride hexahydrate is a yellow crystalline salt which is very soluble in water and alcohols. It occurs in nature as the mineral molysite. It is manufactured from iron and chlorine or from ferric oxide and hydrogen chloride. The anhydrous salt is then hydrated to produce the hexahydrate Ferric trichloride. It is used in water treatment, copper etching, photoengraving, photography, the manufacture of pigments and ink and as laboratory reagent.
- Other Names: Iron trichloride, Ferric chloride hexahydrate, Iron III chloride hexahydrate, Molysite, Flores martis,
- Formula: FeCl3 6H2O
- EEC No. 231–729–4
- CAS No. 10025–77–1
- UN No. 1773
- Purity >97%
- Appearance: Yellow / brown crystalline solid
- Molar mass: 270.3 g/mol
- Density: 1.82 g/cm3
- Melting point: 37 C
- Boiling Point: 280 C decomposes
- Solubility in water: 92 g/100 mL @20C
- pH: 2 (0.1M in water)
- Vapour pressure: 1 hPa (1 mmHg) at 194C
Ferric chloride is soluble in water, acetone, methanol, ethanol and diethyl ether. Iron(III) chloride undergoes hydrolysis to give an acidic solution. The chemical composition of ferric chloride hexahydrate is Fe 20.66% Cl 39.35% and Water 39.99%. The crystal structure of ferric chloride hexahydrate has been determined from x-ray diffraction to show that in the crystals two chloride ions and four water molecules are arranged around each ferric ion to form octahedral [FeCl2(OH2)4]+ ions.
Uses for Ferric chloride
Ferric Chloride forms a corrosive solution which is used as a coagulant in sewage and wastewater treatment and drinking water production. It is used to remove suspended solids and particulate matter from water. As a flocculant it has the function of precipitating heavy metals and sulfides, bleaching, deodorization, degreasing, sterilizing, dephosphorizing and decreasing the COD & BOD of effluent water.
It is commonly used as an etchant for copper-based metals in printed circuit boards. Iron(III) chloride etches copper in a two-step redox reaction to copper(I) chloride and then to copper(II) chloride in the production of printed circuit boards. “Click Here” for instructions on how to make up etching solution.
Other uses include:
- The anhydrous Ferric chloride is a powerful dehydrating agent and is used as a drying agent in certain reactions.
- Staining blades of swords and knives.
- Etching the widmanstatten pattern in iron meteorites.
- For the etching of photogravure plates for printing photographic and fine art images in intaglio and for etching rotogravure cylinders used in the printing industry.
- In the manufacture of pigments and inks.
- Used in veterinary practice to treat overcropping of an animal’s claws.
- Sometimes used in the technique of Raku firing as an additive during the reduction process, turning a pottery piece a burnt orange color due to the iron content present in the reducing atmosphere.
- Used to test the pitting and crevice corrosion resistance of stainless steels and other alloys.
- It is also used as a leaching agent in chloride hydrometallurgy. Used in the chlorination of silver and copper ores.
- Iron(III) chloride is used as catalyst for the reaction of ethylene with chlorine, forming ethylene dichloride (1,2-dichloroethane), an important commodity chemical, which is mainly used for the industrial production of vinyl chloride, the monomer for making PVC.
- As an oxidizer and mordant in dyeing and printing textiles.
- In the construction industry it can enhance the unit strength of concrete when adding a little of ferric chloride solution to the concrete mix.
- Used by American coin collectors to identify the dates of Buffalo nickels that are so badly worn that the date is no longer visible.
- Ferric chloride is used to make red-brown rosinates in varnishes.
Ferric chloride In the laboratory
iron(III) chloride is commonly employed as a Lewis acid for catalysing reactions such as chlorination of aromatic compounds and Friedel-Crafts reaction of aromatics. It forms adducts with Lewis bases such as triphenylphosphine oxide, e.g. FeCl3(OPPh3)2.
Iron(III) chloride is a mild oxidising agent, for example, it is capable of oxidising copper(I) chloride to copper(II) chloride.
When heated with iron(III) oxide at 350C, iron(III) chloride gives iron oxychloride.
Reducing agents such as hydrazine convert iron(III) chloride to complexes of iron(II).
Reacts with cyclopentadienyl magnesium bromide in one preparation of ferrocene, a metal-sandwich complex.
Used in conjunction with NaI in acetonitrile to mildly reduce organic azides to primary amines.
It is used to produce Weigerts iron hematoxylin solution for nuclear stains and trichrome staining.
Health & safety R22 Harmful if swallowed. R34 Causes burns.
Safety phrases: S26 In case of contact with eyes, rinse immediately with plenty of water and seek medical advice. S36/37/39 Wear suitable protective clothing, gloves and eye/face protection. S45 In case of accident or if you feel unwell, seek medical advice immediately (show the label where possible).
For full details see MSDS for Ferric chloride hexahydrate