Ferric chloride is an inorganic compound consisting of an iron element with an oxidation state of +3. Ferric chloride exists as an orange to brown-black colored solid and is otherwise called Molysite. The molecular formula and molecular weight of ferric chloride are FeCl3 and 162.204 g/mol, respectively. Ferric chloride is generally slightly soluble in water.
The solution of ferric chloride is either colorless or light brown. Ferric chloride solution has an odor of faint hydrochloric acid. Ferric chloride solution is corrosive to human tissues and other metals as well. The non-combustible ferric chloride solution is used in the treatment of sewage and purification of water.
The synthesis of ferric chloride can be carried out using different methods based on the requirement. The various methods of synthesizing ferric chloride are given below.
1. The reaction of iron and chlorine
The treatment of iron with chlorine molecules results in the formation of ferric chloride. This method is primarily used to prepare anhydrous ferric chloride. 2 Fe + 3 Cl2 → 2 FeCl3
2. Reaction of iron ore with HCl
Aqueous solutions of ferric chloride are obtained from iron ore as well. Iron ore produces ferric chloride solution in the presence of strong hydrochloric acid. Fe3O4 + 8HCl 🡪 FeCl2 + 2FeCl3 + 4H2O
3. Reaction of ferrous chloride with chlorine
Ferrous chloride that exists in the +2 oxidation state can produce ferric chloride solution. The reaction of ferrous chloride and chlorine molecules produces solutions of ferric chloride having a +3 oxidation state. 2FeCl2 + Cl2 🡪 2FeCl3
4. Reaction of ferrous chloride with oxygen
Ferrous chloride, in the presence of hydrochloric acid, reacts with oxygen and yields ferric chloride solution. 4FeCl2 + O2 + 4HCl 🡪 4FeCl3 + 2H2O
The physical properties of ferric chloride are as follows.
The chemical reactions of ferric chloride are as follows.
1. The reaction of ferric chloride with water
The reaction of ferric chloride with water is exothermic, i.e., heat is released. This reaction produces a strongly acidic solution.
2.Heating of ferric chloride
When ferric chloride is heated at a temperature of 350 °C, a unique iron compound is formed called the iron oxychloride.
3.Reaction of ferric chloride with carboxylate anions
Ferric chloride readily reacts with carboxylate anions or oxalates, giving rise to salt complexes such as tartrate and citrate.
4. Reaction of ferric chloride with alkali metal alkoxides
The reaction of ferric chloride with alkali metal alkoxides results in the formation of iron alkoxide complexes. The complexes may be dimeric or trimeric.
5. Reaction of ferric chloride with chlorobenzene
Ferric chloride reacts with chlorobenzene resulting in the formation of a di-substituted product called dichlorobenzene. The byproducts of this reaction are hydrochloric acid and ferrous chloride.
6. Reaction of ferric chloride with organometallic compounds
Ferric chloride is reactive towards organometallic compounds such as methyl lithium. In the presence of ether, ferric chloride reacts with methyl lithium to produce a greenish-yellow complex called lithium tetrachloroferrate(III). The reaction proceeds forward in the presence of excess methyl lithium and gives rise to lithium tetrachloroferrate(II).
7. Reduction-oxidation reactions of ferric chloride
Ferric chloride acts as a mild oxidizing agent and hence participates in several redox reactions.
Ferric chloride finds various applications in pharmaceutical and industrial sectors as well. The various applications of ferric chloride are as follows.