Aluminum sulfate

From Crystal growing

<amp/>


   Aluminum sulfate   
Names: aluminum sulfate
cake alum
filter alum
papermaker's alum

Formula: Al2(SO4)3 (anhydrous)
Al2(SO4)3 · 18H2O (octadecahydrate)
SMILES: [O-]S(=O)(=O)[O-].[O-]S(=O)(=O)[O-].[O-]S(=O)(=O)[O-].[Al+3].[Al+3]
Molar mass: 342.147 g/mol (anhydrous)
666.415 g/mol (octadecahydrate)
Density: 2.710 g/cm3 (anhydrous)
1.69 g/cm3 (octadecahydrate)
Crystal system: monoclinic (octadecahydrate)
α=90°, γ=90°
hexagonal (anhydrous)
a=8.032 Å, b=8.032 Å, c=21.36 Åα=90°, β=90°, γ=120°
monoclinic (pentahydrate)
a=5.4843 Å, b=10.7958 Å, c=20.8427 Åα=90°, β=96.44°, γ=90°
monoclinic (octahydrate)
a=7.37 Å, b=20.008 Å, c=9.624 Åα=90°, β=91.62°, γ=90°
monoclinic (decahydrate)
a=12.4207 Å, b=7.2896 Å, c=20.239 Åα=90°, β=97.121°, γ=90°
triclinic (alunogen)
a=7.42 Å, b=26.97 Å, c=6.02 Åα=89.57°, β=97.34°, γ=91.53°
monoclinic (aluminite)
a=7.44 Å, b=15.583 Å, c=11.7 Åα=90°, β=110.18°, γ=90°
monoclinic (jurbanite)
a=8.3965 Å, b=12.479 Å, c=8.1549 Åα=90°, β=101.917°, γ=90°
monoclinic (felsobanyaite)
a=13.026 Å, b=10.015 Å, c=11.115 Åα=90°, β=104.34°, γ=90°
Shapes:
https://media.crystalls.info/w/uploads/media/Spherolit.json
https://media.crystalls.info/w/uploads/media/Needle.json

Color: white
colorless
Melting point: 86.5 °C359.65 K <br />187.7 °F <br />647.37 °R <br /> (octadecahydrate)
Decomposition point: 580 °C853.15 K <br />1,076 °F <br />1,535.67 °R <br /> (anhydrous)
150 °C423.15 K <br />302 °F <br />761.67 °R <br /> (octadecahydrate)
160 °C433.15 K <br />320 °F <br />779.67 °R <br /> (tetradecahydrate)
250 °C523.15 K <br />482 °F <br />941.67 °R <br /> (decahydrate)
420 °C693.15 K <br />788 °F <br />1,247.67 °R <br /> (trihydrate)
Refractive index: 1.47 (octadecahydrate)
Magnetic properties: diamagnetic
χ=-9.30 · 10-5cm³/mol
Hardness: fragile
(1.5 on Moh's scale)
Toxicity: slightly toxic
LD50=980mg/kg

Description

Inorganic compound, salt of transitional metal aluminum and inorganic sulfuric acid From water solutions crystallizes as octadecahydrate.

Minerals

Occurs in nature as alunogen, aluminite, rostite, jurbanite and felsobanyaite minerals.

Precursors

Reaction between aluminum hydroxide and sulfuric acid

Chemical equation:

2Al(OH)3 + 3H2SO4 = Al2(SO4)3 + 6H2O


For preparation of 100.00g of aluminum sulfate octadecahydrate а 23.41g of aluminum hydroxide and 119.33g of 37% sulfuric acid is required.

Add acid to the flask, then add small parts of aluminum compound with stirring until it will totally dissolve . After reaction will stop, filter the solution and use it for crystal growing.

Reaction between potassium alum, sodium hydroxide and sulfuric acid

Chemical equation:

2KAl(SO4)2 + 6NaOH = K2SO4 + 3 Na2SO4 + 2Al(OH)3
2Al(OH)3 + 3H2SO4 = Al2(SO4)3 + 6H2O


For preparation of 100.00g of aluminum sulfate octadecahydrate а 77.49g of aluminum-potassium sulfate and 36.01g of sodium hydroxide or 119.33g of 37% sulfuric acid is required.

Add to the flask with alums solution small parts of sodium hydroxide solution and stir. The large amount of poorly soluble precipitate will form. Settle it out and wash it from soluble impurities few times.Add acid to the flask, then add small parts of aluminum compound with stirring until it will totally dissolve . After reaction will stop, filter the solution and use it for crystal growing.

Reaction between metal aluminum and sulfuric acid

Chemical equation:

2Al + 3H2SO4 = Al2(SO4)3 + 3H2


For preparation of 100.00g of aluminum sulfate octadecahydrate а 8.10g of чистый aluminum and 119.33g of 37% sulfuric acid is required.

Add diluted acid solution to the flask, then add aluminum pieces, shavings or powder and stir it until gas emission will stop. After reaction will stop, filter the solution and use it for crystal growing.

Influence of pH level

Addition of sulfuric acid prevents compounds hydrolysis.

Storage conditions

Store in its original form or under several layers of varnish at average humidity and room temperature. Do not store in matchboxes or cotton wool and do not heat.

Solubility

Temperatureгр/100,00 гр waterгр/100,00 гр ethylene glycol
(anhydrous)(octadecahydrate)(anhydrous)
0°C273.15 K <br />32 °F <br />491.67 °R <br />31.286.85
10°C283.15 K <br />50 °F <br />509.67 °R <br />33.595.8
15°C288.15 K <br />59 °F <br />518.67 °R <br />~35.0~102
20°C293.15 K <br />68 °F <br />527.67 °R <br />36.4107.3516.8
25°C298.15 K <br />77 °F <br />536.67 °R <br />38.5~117
30°C303.15 K <br />86 °F <br />545.67 °R <br />40.4127.6
40°C313.15 K <br />104 °F <br />563.67 °R <br />45.8167.6
50°C323.15 K <br />122 °F <br />581.67 °R <br />52.2201.4
60°C333.15 K <br />140 °F <br />599.67 °R <br />59.2262.6
70°C343.15 K <br />158 °F <br />617.67 °R <br />~66.1348.2
80°C353.15 K <br />176 °F <br />635.67 °R <br />73~600
90°C363.15 K <br />194 °F <br />653.67 °R <br />80.8~852
100°C373.15 K <br />212 °F <br />671.67 °R <br />89.041104
Slightly soluble in ethanol and methanol.


Gallery


Video


Sources


Navigation