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 AlH3.

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 150oC.

Aluminium hydride boiling point

AlH3 decomposes on heating at 110oC 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.

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


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.

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Aluminium hydrides
Aluminium Chemical Properties
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