Aluminium hydrides Properties (25 Helpful Facts)

Aluminium hydride is also known as alane. It is an inorganic compound, commonly used as a reducing agent in industrial and laboratory. Let us discuss some of the facts in detail.

Aluminum hydride exist as a dimer as it is a self-polymerised species. In the etherial solvents such as tetrahydrofuran or diethyl ether alane complexes with the Lewis bases and it also reacts selectively with the organic compounds containing carboxylic acids and esters as the functional groups.

Aluminium hydride is a needle like crystals. Let us discuss some basic properties of aluminium hydride like the melting point, boiling point, atomic radius, viscosity and odour in details.

Aluminium hydride IUPAC name

The IUPAC name of AlH₃ is aluminium hydride.

Aluminium hydride chemical formula

The chemical formula of aluminium hydride is AlH_3.

Aluminium hydride CAS number

The CAS number of AlH₃ is 7784-21-6.

Aluminium hydride ChemSpider ID

The chemSpider ID of AlH₃ is 13833.

Aluminium hydride chemical classification

AlH₃ belongs the boron family.
Boron family is electron deficient and hence AlH₃ is also electron deficient and so it polymerises to become stable compound.

Aluminium hydride molar mass

The molar mass of AlH₃ is 29.99 g/mol. It is the cumulative of aluminium and three hydrogen. The atomic mass of aluminium is 26.98u and of hydrogen is 1.00u.

Aluminium hydride colour

AlH₃ is white crystalline solid that maybe tinted grey in colour which is due to the impurity present in the compound.

Aluminium hydride viscosity

The viscosity of AlH₃ is 65.1 cps.

Aluminium hydride molar density

The molar density of AlH₃ is 1.477 g/L.

Aluminium hydride melting point

The melting point of AlH₃ is 150^oC.

Aluminium hydride boiling point

AlH₃ decomposes on heating at 110^oC as it is highly reactive.

Aluminium hydride state at room temperature

AlH₃ is crystalline at room temperature. It is a non-volatile solid.

Aluminium hydride covalent bond

AlH₃ is covalent in nature as the bond between the aluminium and is hydrogen is formed by the sharing of the electrons.

Aluminium hydride ionic/covalent radius

The covalent radius of AlH₃ is 172pm which is the distance between the aluminium and the hydrogen atom in the compound.

Aluminium hydride electron configurations

The arrangement of electrons in the different orbitals of an atom is called electronic configurations. Let us see the electronic configuration of aluminium hydride.

AlH₃ contains aluminium with electronic configuration of 1s²2s²2p⁶3s²3p¹ and hydrogen having electronic configuration of 1s¹.

Aluminium hydride oxidation state

The oxidation state of aluminium in AlH₃ is +3.

Aluminium hydride acidity/alkaline

AlH₃ is a Lewis acid because it is an electron-deficient species forming adduct with the electropositive species.

Is Aluminium hydride odourless?

AlH₃ is odourless in nature.

Is Aluminium hydride paramagnetic?

Paramagnetism is shown by the species which have the unpaired electrons. These species are not attracted by the magnetic field.

AlH₃ is paramagnetic species as there is an unpaired electrons present in aluminium and hydrogen.

Aluminium hydride hydrates

AlH₃ reacts with water to form aluminium hydroxide.

AlH₃+H₂O–>Al(OH)₃ + H₂

Aluminium hydride crystal structure

The shape of AlH₃ is trigonal planar in shape.

Gamma aluminium hydride — **Image credit** : Aluminium hydride by Seclanium (CC BY 3.0)

Aluminium hydride polarity and conductivity

AlH₃ is non polar compound as the net dipole moment is 0.
AlH₃ conducts electricity at high temperature and pressure.

Aluminium hydride reaction with acid

AlH₃ reacts with acids to give lithium aluminium hydride.

AlH₃ + LiH → LiAlH₄

Aluminium hydride reaction with base

AlH₃ reacts with trimethylamine in the solid phase to form a dimeric with bridging hydrogen atoms.

AlH₃+ N(CH₃)₃–> (NMe₃Al(μ-H))₂

Aluminium hydride reaction with oxide

AlH₃ reacts with the oxide to form a adduct as shown in the reaction. In this reaction aluminium hydride reacts with the diethyl ether to form adduct.

AlH₃ + (C₂H₅)₂O → H₃Al · O(C₂H₅)₂

Aluminium hydride reaction with metal

AlH₃ reacts with the metal to form the respective compound by the process of metathesis.

2MAlH₄+ MgCl₂—> Mg(AlH₄)₂ . 4THF + MCl

Conclusion

As we have seen the various properties of aluminium hydride like the melting point, boiling point, ionic radius. Its various chemical properties like the reactions with the acids, bases, oxides are discussed. It is also widely used as lithium aluminium hydride as reducing agents in the organic chemistry.