Aluminium nitrate

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Aluminium nitrate
Aluminium nitrate nonahydrate.jpg
Aluminium nitrate nonahydrate sample
Names
IUPAC name
Aluminium nitrate
Preferred IUPAC name
Aluminium nitrate
Other names
Aluminium(III) nitrate
Aluminum nitrate
Nitric acid, aluminum salt
Aluminum trinitrate
Properties
Al(NO3)3 (anhydrous)
Al(NO3)3·9H2O (nonahydrate)
Molar mass 212.996 g/mol (anhydrous)
375.134 g/mol (nonahydrate)
Appearance White hygroscopic crystals
Odor Odorless (fresh)
Slightly pungent (old)
Density 1.72 g/cm3 (nonahydrate)
Melting point 66 °C (151 °F; 339 K) (anhydrous)
73.9 °C (165.0 °F; 347.0 K) (nonahydrate)
Boiling point 150 °C (302 °F; 423 K) (nonahydrate); decomposes
anhydrous:
60.0 g/100 ml (0 °C)
73.9 g/100 ml (20 °C)
160 g/100 ml (100 °C)
nonahydrate:
67.3 g/100 ml
Solubility Insoluble in chloroform, dichloromethane, toluene, xylene
Solubility in methanol 14.45 g/100 ml
Solubility in ethanol 8.63 g/100 ml
Solubility in ethylene glycol 18.32 g/100 ml
Hazards
Safety data sheet Sigma-Aldrich
Flash point 35 °C (95 °F; 308 K) (nonahydrate)
Lethal dose or concentration (LD, LC):
4,280 mg/kg (oral, rat)
Related compounds
Related compounds
Aluminium sulfate
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

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

Thermal decomposition of aluminum nitrate produces aluminium oxide, nitrogen dioxide and oxygen. This reaction takes place between 150-200 °C.

2 Al(NO3)3 → Al2O3 + 6 NO2 + 3/2 O2

Physical

Aluminium nitrate is an odorless, white crystalline hygroscopic salt. It has good solubility in water (73.9 g/100 ml at 20 °C), but is less 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.[1]

If you want to avoid the fumes, use aluminium hydroxide as a precursor chemical, which can be obtained by adding a soluble hydroxide to an aluminium salt. This reaction however will yield the hydrated form.

Obtaining anhydrous aluminium nitrate is difficult, as it tends to decompose when heated, making it a poor choice for oxidizer in pyrotechnic mixtures.

Projects

  • Make alumina nanoparticles[2]
  • Pyrotechnic mixtures
  • Make nitrogen dioxide
  • Compound collecting

Handling

Safety

Aluminium compounds are toxic and should be handled with care. Thermal decomposition of aluminium nitrate yields nitrogen dioxide which is corrosive and very toxic.

Storage

The anhydrous form must be stored in good airtight containers, while the nonahydrate should be stored away from moisture, in airtight bottles. Aluminium nitrate nonahydrate samples will take on a slight yellowish tint after several years of contact with air.

Disposal

Adding sodium hydroxide or any other base will neutralize the compound to aluminium hydroxide, which is easier to take care of.

References

  1. https://www.youtube.com/watch?v=u4Ha1SJrazY
  2. http://nopr.niscair.res.in/bitstream/123456789/28846/1/IJPAP%2052%286%29%20378-385.pdf

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