Aluminum+Chloride

Aluminum chloride(AlCl3) is the main compound of aluminumand chlorine. It is white, but samples are often contaminated with iron trichloride, giving it a yellow color. The solid has a low melting and boiling point. It is mainly produced and consumed in the production of aluminium metal, but large amounts are also used in other areas of chemical industry. The compound is often cited as a Lewis acid. It is an example of an inorganic compound that "cracks" at mild temperature, reversibly changing from a polymer to a molecule. Aluminum Chloride, as called aluminum trichloride, is also used as a preservative for wood or as a catalyst. In low concentration it is also used as a very powerful antiperspirant, which can treat excessive sweating of the armpits, hands, or feet. Aluminium chloride can be found in a roll-on applicator, but is only available from pharmacies. Aluminum Chloride is has a molecular weight of 133.340538. When Aluminum Chloride comes in contact with water it hydrolyzes to form aluminum hydroxide and hydrochloric acid. This reaction cause is violent and a large amount of heat is produced.





** Structure **
AlCl3 adopts three different structures, depending on the temperature and the state (solid, liquid, gas). Solid AlCl3 is a sheet-like layered cubic close packed layers. In this framework, the Al centres exhibit octahedral coordination geometry.[3] In the melt, aluminium trichloride exists as the dimer Al2Cl6, with tetracoordinate aluminium. This change in structure is related to the lower density of the liquid phase (1.78 g/cm3) vs solid aluminium trichloride (2.48 g/cm3). Al2Cl6 dimers are also found in the vapour phase. At higher temperatures, the Al2Cl6 dimers dissociate into trigonal planar AlCl3, which is structurally analogous to BF3. The melt conducts electricity poorly,[4] unlike more ionic halides such as sodium chloride.

Reactions
Anhydrous aluminium chloride is a powerful Lewis acid, capable of forming Lewis acid-base adducts with even weak Lewis bases such as benzophenone and mesitylene.[5] It forms tetrachloroaluminate AlCl4− in the presence of chloride ions. Aluminium chloride reacts with calcium and magnesium hydrides in tetrahydrofuran forming tetrahydroaluminates:

Reactions with water
Aluminium chloride is hygroscopic, having a very high affinity for water. It fumes in moist air and hisses when mixed with liquid water as the Cl- ions are displaced with H2O molecules in the lattice to form the hexahydrate AlCl3·6H2O (also white to yellowish in color). The anhydrous phase cannot be regained on heating as HCl is lost leaving aluminium hydroxide or alumina (aluminium oxide): Al(H2O)6Cl3 → Al(OH)3 + 3 HCl + 3 H2O On strong heating (~400°C), the aluminium oxide is formed from the aluminium hydroxide via: 2 Al(OH)3 → Al2O3 + 3 H2O Aqueous solutions of AlCl3 are ionic and thus conduct electricity well. Such solutions are found to be acidic, indicative of partial hydrolysis of the Al3+ ion. The reactions can be described (simplified) as: [Al(H2O)6]3+ ⇌ [Al(OH)(H2O)5]2+ + H+ Aqueous solutions behave similarly to other aluminium salts containing hydrated Al3+ ions, giving a gelatinous precipitate of aluminium hydroxide upon reaction with sodium hydroxide: AlCl3 + 3 NaOH → Al(OH)3 + 3NaClF

Safety : One needs to take precautions with this substance as well as it can cause irritation to eyes, skin, and the respiratory system if inhaled or on contact.


 * aluminum chloride** - a chloride used as a wood preservative or catalyst

Fun Fact:
Deodorant contains Aluminum Chloride, which can help stop the bleeding of a cut face when shaving: Stop the bleeding!