Aluminum sulfate

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  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°
90°  
, γ=90°
90°  

hexagonal (anhydrous)
a=8.032 Å
8.0320 Å
0.8032 nm
, b=8.032 Å
8.0320 Å
0.8032 nm
, c=21.36 Å
21.3600 Å
2.1360 nm
α=90°
90°  
, β=90°
90°  
, γ=120°
120°  

monoclinic (pentahydrate)
a=5.4843 Å
5.4843 Å
0.5484 nm
, b=10.7958 Å
10.7958 Å
1.0796 nm
, c=20.8427 Å
20.8427 Å
2.0843 nm
α=90°
90°  
, β=96.44°
96°26′24.0″  
, γ=90°
90°  

monoclinic (octahydrate)
a=7.37 Å
7.3700 Å
0.7370 nm
, b=20.008 Å
20.0080 Å
2.0008 nm
, c=9.624 Å
9.6240 Å
0.9624 nm
α=90°
90°  
, β=91.62°
91°37′12.0″  
, γ=90°
90°  

monoclinic (decahydrate)
a=12.4207 Å
12.4207 Å
1.2421 nm
, b=7.2896 Å
7.2896 Å
0.7290 nm
, c=20.239 Å
20.2390 Å
2.0239 nm
α=90°
90°  
, β=97.121°
97°7′15.6″  
, γ=90°
90°  

triclinic (alunogen)
a=7.42 Å
7.4200 Å
0.7420 nm
, b=26.97 Å
26.9700 Å
2.6970 nm
, c=6.02 Å
6.0200 Å
0.6020 nm
α=89.57°
89°34′12.0″  
, β=97.34°
97°20′24.0″  
, γ=91.53°
91°31′48.0″  

monoclinic (aluminite)
a=7.44 Å
7.4400 Å
0.7440 nm
, b=15.583 Å
15.5830 Å
1.5583 nm
, c=11.7 Å
11.7000 Å
1.1700 nm
α=90°
90°  
, β=110.18°
110°10′48.0″  
, γ=90°
90°  

monoclinic (jurbanite)
a=8.3965 Å
8.3965 Å
0.8397 nm
, b=12.479 Å
12.4790 Å
1.2479 nm
, c=8.1549 Å
8.1549 Å
0.8155 nm
α=90°
90°  
, β=101.917°
101°55′1.2″  
, γ=90°
90°  

monoclinic (felsobanyaite)
a=13.026 Å
13.0260 Å
1.3026 nm
, b=10.015 Å
10.0150 Å
1.0015 nm
, c=11.115 Å
11.1150 Å
1.1115 nm
α=90°
90°  
, β=104.34°
104°20′24.0″  
, γ=90°
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 °C
359.65 K
187.7 °F
647.37 °R
(octadecahydrate)
Decomposition point: 580 °C
853.15 K
1,076 °F
1,535.67 °R
(anhydrous)
150 °C
423.15 K
302 °F
761.67 °R
(octadecahydrate)
160 °C
433.15 K
320 °F
779.67 °R
(tetradecahydrate)
250 °C
523.15 K
482 °F
941.67 °R
(decahydrate)
420 °C
693.15 K
788 °F
1,247.67 °R
(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°C
273.15 K
32 °F
491.67 °R
31.2
31.2 g/100g
23.78 %
86.85
86.85 g/100g
46.481 %
10°C
283.15 K
50 °F
509.67 °R
33.5
33.5 g/100g
25.094 %
95.8
95.8 g/100g
48.927 %
15°C
288.15 K
59 °F
518.67 °R
~35.0
35 g/100g
25.926 %
~102
102 g/100g
50.495 %
20°C
293.15 K
68 °F
527.67 °R
36.4
36.4 g/100g
26.686 %
107.35
107.35 g/100g
51.772 %
16.8
16.8 g/100g
14.384 %
25°C
298.15 K
77 °F
536.67 °R
38.5
38.5 g/100g
27.798 %
~117
117 g/100g
53.917 %
30°C
303.15 K
86 °F
545.67 °R
40.4
40.4 g/100g
28.775 %
127.6
127.6 g/100g
56.063 %
40°C
313.15 K
104 °F
563.67 °R
45.8
45.8 g/100g
31.413 %
167.6
167.6 g/100g
62.631 %
50°C
323.15 K
122 °F
581.67 °R
52.2
52.2 g/100g
34.297 %
201.4
201.4 g/100g
66.821 %
60°C
333.15 K
140 °F
599.67 °R
59.2
59.2 g/100g
37.186 %
262.6
262.6 g/100g
72.421 %
70°C
343.15 K
158 °F
617.67 °R
~66.1
66.1 g/100g
39.795 %
348.2
348.2 g/100g
77.689 %
80°C
353.15 K
176 °F
635.67 °R
73
73 g/100g
42.197 %
~600
600 g/100g
85.714 %
90°C
363.15 K
194 °F
653.67 °R
80.8
80.8 g/100g
44.69 %
~852
852 g/100g
89.496 %
100°C
373.15 K
212 °F
671.67 °R
89.04
89.04 g/100g
47.101 %
1104
1,104 g/100g
91.694 %
Slightly soluble in ethanol and methanol.

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