Aluminium nitrate
Aluminium nitrate is a salt of aluminium and nitric acid, existing normally as a crystalline hydrate, most commonly as aluminium nitrate nonahydrate, Al(NO3)3·9H2O, with a molecular formula weight of 375.13.
Synthesis
Aluminium nitrate can be easily prepared by the reaction of aluminum hydroxide with nitric acid:
- Al(OH)3 + 3HNO3 -> Al(NO3)3 + 3H2O
The synthesis from aluminium metal has many problems since aluminium is not attacked by nitric acid because of its protective oxide layer. The process involves an initial basic attack with KOH, followed by partial neutralization with nitric acid to precipitate the hydroxide. The hydroxide is then filtered and washed thoroughly to remove soluble potassium nitrate. After this, the filtered aluminium hydroxide is reacted with excess nitric acid. The crystals are very deliquescent and must be stored in dry conditions.
Uses
Aluminium nitrate is a strong oxidizing agent. It is used in tanning leather, antiperspirants, corrosion inhibitors, extraction of uranium, petroleum refining, and as a nitrating agent. It is used in the laboratory and classroom such as in the reaction:
Al(NO3)3 + 3NaOH --> Al(OH)3 + 3NaNO3
References
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External links
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