Aluminium nitrate

Aluminium nitrate nonahydrate sample.

Aluminium nitrate is a salt of aluminium and nitric acid, existing normally as a crystalline nonahydrate, Al(NO₃)₃·9H₂O.

Properties

Chemical

Aluminium nitrate reacts with sodium hydroxide, precipitating aluminium hydroxide:

Al(NO₃)₃ + 3 NaOH → Al(OH)₃ + 3 NaNO₃

Physical

Aluminium nitrate is an odorless, white crystalline hygroscopic salt. It has good solubility in water (73.9 g/100ml at 20 °C), but is poorly soluble in alcohols and ethylene glycol. It melts at 66 °C (anhydrous) and 73.9 °C (nonahydrate), and if heated higher the nonahydrate will decompose.

Availability

Aluminium nitrate is sold by chemical suppliers. It can sometimes be found on eBay.

Preparation

Aluminium nitrate cannot be made by adding aluminium to nitric acid, as the aluminium forms a passivation layer which prevents the reaction from taking place. One way around it is to add nitric acid to another compound of aluminium, such as aluminium chloride, reaction which gives off nitrosyl chloride fumes.

If you want to avoid the fumes, use aluminium hydroxide as a precursor chemical. This reaction however will yield the hydrated form.

Projects

• Make alumina nanoparticles

Handling

Safety

Aluminium compounds are toxic and should be handled with care.

Storage

The anhydrous form must be stored in airtight containers, while the nonahydrate should be stored away from moisture.

Disposal

Adding a hydroxide or any other base will neutralize the compound.

References

Relevant Sciencemadness threads

• Aluminium Nitrate Synthesis