Difference between revisions of "Aluminium sulfate"

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(Created page with "{{Chembox | Name = Aluminium sulfate | Reference = | IUPACName = Aluminium sulfate | PIN = | SystematicName = Aluminium sulfate | OtherNames = Aluminium sulphate<br>Alunogenit...")
 
 
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| PIN =
 
| PIN =
 
| SystematicName = Aluminium sulfate
 
| SystematicName = Aluminium sulfate
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| OtherNames = Aluminium sulphate<br>Alunogenite<br>Cake alum<br>Dialuminum sulfate<br>Filter alum<br>Papermaker's alum
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| OtherNames = Aluminium sulphate<br>Alunogenite<br>Cake alum<br>Dialuminum sulfate<br>Filter alum<br>Papermaker's alum<br>Vitriol of argile<br>Vitriol of clay
 
<!-- Images -->
 
<!-- Images -->
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| ImageFile = Aluminium sulfate flocculant tablet.jpg
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| ImageFile = Aluminium sulfate crystals on watch glass.jpg
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| ImageSize = 250
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| ImageSize = 300
 
| ImageAlt =  
 
| ImageAlt =  
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| ImageCaption = Aluminium sulfate flocculant tablet on a watchglass.
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| ImageCaption = Lab-grade crystals of aluminium sulfate
 
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| MeltingPt_ref =  
 
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| MeltingPt_notes = (anhydrous); decomposes<br>86.5°C (octadecahydrate)
 
| MeltingPt_notes = (anhydrous); decomposes<br>86.5°C (octadecahydrate)
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| Odour = Odorless
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| Odor = Odorless
 
| pKa = 3.3-3.6
 
| pKa = 3.3-3.6
 
| pKb =  
 
| pKb =  
 
| Solubility = 31.2 g/100 mL (0 °C)<br>36.4 g/100 mL (20 °C)<br>89.0 g/100 mL (100 °C)
 
| Solubility = 31.2 g/100 mL (0 °C)<br>36.4 g/100 mL (20 °C)<br>89.0 g/100 mL (100 °C)
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| SolubleOther =  
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| SolubleOther = Insoluble in organic solvents
 
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| LD50 =  
 
| LD50 =  
 
| LC50 =  
 
| LC50 =  
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| MainHazards =  
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| MainHazards = Irritant<br>Corrosive
 
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| NFPA-F =  
 
| NFPA-H =  
 
| NFPA-H =  
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| OtherFunction =  
 
| OtherFunction =  
 
| OtherFunction_label =  
 
| OtherFunction_label =  
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| OtherCompounds =  
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| OtherCompounds = [[Aluminium sulfide]]
 
   }}
 
   }}
 
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'''Aluminium sulfate''' is a chemical compound with the formula Al<sub>2</sub>(SO<sub>4</sub>)<sub>3</sub>, used mostly as a flocculating agent in the purification of drinking water.
+
'''Aluminium sulfate''' is a chemical compound with the formula '''Al<sub>2</sub>(SO<sub>4</sub>)<sub>3</sub>''', used mostly as a flocculating agent in the purification of drinking water or to reduce the pH of garden soil.
  
 
==Properties==
 
==Properties==
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When aluminium sulfate reacts with an alkaline hydroxide, such as [[sodium hydroxide]], [[aluminium hydroxide]] precipitates:
 
When aluminium sulfate reacts with an alkaline hydroxide, such as [[sodium hydroxide]], [[aluminium hydroxide]] precipitates:
  
−
:Al<sub>2</sub>(SO<sub>4</sub>)<sub>3</sub> + 3 NaOH → 2 Al(OH)<sub>3</sub> + 3/2 Na<sub>2</sub>SO<sub>4</sub>
+
: Al<sub>2</sub>(SO<sub>4</sub>)<sub>3</sub> + 3 NaOH → 2 Al(OH)<sub>3</sub> + 3/2 Na<sub>2</sub>SO<sub>4</sub>
  
 
Alumnium sulfate decomposes when heated to 770 °C, to release [[sulfur trioxide]] vapors and leave behind [[aluminium oxide|alumina]]:
 
Alumnium sulfate decomposes when heated to 770 °C, to release [[sulfur trioxide]] vapors and leave behind [[aluminium oxide|alumina]]:
  
−
:Al<sub>2</sub>(SO<sub>4</sub>)<sub>3</sub> → Al<sub>2</sub>O<sub>3</sub> + SO<sub>3</sub>
+
: Al<sub>2</sub>(SO<sub>4</sub>)<sub>3</sub> → Al<sub>2</sub>O<sub>3</sub> + SO<sub>3</sub>
  
 
Aluminium sulfate slowly hydrolyzes in water to release diluted [[sulfuric acid]].
 
Aluminium sulfate slowly hydrolyzes in water to release diluted [[sulfuric acid]].
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Aluminium sulfate is an odorless, white hygroscopic crystalline compound, moderately soluble in water and insoluble in organic solvents. It has an acidic taste.
 
Aluminium sulfate is an odorless, white hygroscopic crystalline compound, moderately soluble in water and insoluble in organic solvents. It has an acidic taste.
  
−
Aluminium sulfate forms a number of different hydrates, the most common ones being the hexadecahydrate Al<sub>2</sub>(SO<sub>4</sub>)<sub>3</sub>•16H<sub>2</sub>O and octadecahydrate Al<sub>2</sub>(SO<sub>4</sub>)<sub>3</sub>•18H<sub>2</sub>O. A rarer form, the heptadecahydrate, written as [Al(H<sub>2</sub>O)<sub>6</sub>]<sub>2</sub>(SO<sub>4</sub>)<sub>3</sub>•5H<sub>2</sub>O, occurs naturally as the mineral alunogen.
+
Aluminium sulfate is rarely encountered in the anhydrous form. Aluminium sulfate forms a number of different hydrates, the most common ones being the hexadecahydrate Al<sub>2</sub>(SO<sub>4</sub>)<sub>3</sub>·16H<sub>2</sub>O and octadecahydrate Al<sub>2</sub>(SO<sub>4</sub>)<sub>3</sub>·18H<sub>2</sub>O. A rarer form, the heptadecahydrate, written as [Al(H<sub>2</sub>O)<sub>6</sub>]<sub>2</sub>(SO<sub>4</sub>)<sub>3</sub>·5H<sub>2</sub>O, occurs naturally as the mineral ''alunogen''.
  
 
==Availability==
 
==Availability==
 
Aluminium sulfate can be bought from various swimming pool and various home-improvement and gardening retailer stores, as flocculant tablets. The tablet always consists of the hydrated form.
 
Aluminium sulfate can be bought from various swimming pool and various home-improvement and gardening retailer stores, as flocculant tablets. The tablet always consists of the hydrated form.
  
−
Anhydrous aluminium sulfate can be purchased from various chemical suppliers.
+
Anhydrous or hydrated aluminium sulfate can be purchased from various chemical suppliers.
  
 
==Preparation==
 
==Preparation==
−
Aluminium sulfate can be made by reacting [[sulfuric acid]] with aluminium sulfate, or with hot [[aluminium]] metal.
+
Aluminium sulfate can be made by reacting [[sulfuric acid]] with aluminium oxide, hydroxide, halide or with hot [[aluminium]] metal.
 +
 
 +
: 2 Al(OH)<sub>3</sub> + 3 H<sub>2</sub>SO<sub>4</sub> → Al<sub>2</sub>(SO<sub>4</sub>)<sub>3</sub> + 6 H<sub>2</sub>O
 +
 
 +
: 2 Al + 3 H<sub>2</sub>SO<sub>4</sub> → Al<sub>2</sub>(SO<sub>4</sub>)<sub>3</sub> + 3 H<sub>2</sub>
  
 
==Projects==
 
==Projects==
 
*Make alum
 
*Make alum
 
*Make [[aluminium nitrate]]
 
*Make [[aluminium nitrate]]
−
*Make aluminium hydroxide
+
*Make aluminium hydroxide and oxide
  
 
==Handling==
 
==Handling==
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Aluminium sulfate has low toxicity compared to other compounds, but it may cause aluminium poisoning if ingested in large quantities. The salt is considered to be toxic to the reproductive system. The anhydrous form is irritant on skin and eye contact, and may irritate the lungs if inhaled. If released in the environment in large quantities, it will raise the level of aluminium in the soil as well as the soil acidity.
 
Aluminium sulfate has low toxicity compared to other compounds, but it may cause aluminium poisoning if ingested in large quantities. The salt is considered to be toxic to the reproductive system. The anhydrous form is irritant on skin and eye contact, and may irritate the lungs if inhaled. If released in the environment in large quantities, it will raise the level of aluminium in the soil as well as the soil acidity.
  
−
Aluminium sulfate slowly hydrolizes in water to yield sulfuric acid which is highly corrosive. [https://en.wikipedia.org/wiki/Camelford_water_pollution_incident In one notorious case], a large amount of aluminium sulfate (20 tonnes) was accidentally dissolved in the Camelford water supply and the resulting sulfuric acid dissolved lead and copper from the city plumbing, causing short-term mass poisoning.
+
Aluminium sulfate slowly hydrolyzes in water to yield sulfuric acid which is highly corrosive. [https://en.wikipedia.org/wiki/Camelford_water_pollution_incident In one notorious case], a large amount of aluminium sulfate (20 tonnes) was accidentally dissolved in the Camelford water supply and the resulting sulfuric acid dissolved lead and copper from the city plumbing, causing short-term mass poisoning.
  
 
===Storage===
 
===Storage===
−
Anhydrous aluminium sulfate must be stored in airtight containers, while the hydrated forms can be stored in any container, away from moisture.
+
Anhydrous aluminium sulfate must be stored in airtight containers, while the hydrated forms can be stored in any container, just keep it away from moisture.
  
 
===Disposal===
 
===Disposal===
 
Aluminium sulfate can be safely poured down the drain, though it's best to heavily dilute it first, to prevent a build-up of sulfuric acid.
 
Aluminium sulfate can be safely poured down the drain, though it's best to heavily dilute it first, to prevent a build-up of sulfuric acid.
 +
 +
==Gallery==
 +
<gallery widths="200" position="center" columns="4" orientation="none">
 +
Aluminium sulfate flocculant tablet.jpg|Aluminium sulfate flocculant tablet on a watch glass.
 +
</gallery>
  
 
==References==
 
==References==
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[[Category:Readily available chemicals]]
 
[[Category:Readily available chemicals]]
 
[[Category:Hygroscopic compounds]]
 
[[Category:Hygroscopic compounds]]
 +
[[Category:Solids]]

Latest revision as of 13:12, 17 June 2019

Aluminium sulfate
Aluminium sulfate crystals on watch glass.jpg
Lab-grade crystals of aluminium sulfate
Names
IUPAC name
Aluminium sulfate
Systematic IUPAC name
Aluminium sulfate
Other names
Aluminium sulphate
Alunogenite
Cake alum
Dialuminum sulfate
Filter alum
Papermaker's alum
Vitriol of argile
Vitriol of clay
Identifiers
Jmol-3D images Image
Properties
Al2(SO4)3
Molar mass 342.15 g/mol (anhydrous)
666.42 g/mol (octadecahydrate)
Appearance White hygroscopic solid
Odor Odorless
Density 2.672 g/cm3 (anhydrous)
1.62 g/cm3 (octadecahydrate)
Melting point 770 °C (1,420 °F; 1,040 K) (anhydrous); decomposes
86.5°C (octadecahydrate)
Boiling point Decomposes
31.2 g/100 mL (0 °C)
36.4 g/100 mL (20 °C)
89.0 g/100 mL (100 °C)
Solubility Insoluble in organic solvents
Acidity (pKa) 3.3-3.6
Thermochemistry
-3440 kJ/mol
Hazards
Safety data sheet ScienceLab
Flash point Non-flammable
Related compounds
Related compounds
 Aluminium sulfide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Aluminium sulfate is a chemical compound with the formula Al2(SO4)3, used mostly as a flocculating agent in the purification of drinking water or to reduce the pH of garden soil.

Properties

Chemical

When aluminium sulfate reacts with an alkaline hydroxide, such as sodium hydroxide, aluminium hydroxide precipitates:

Al2(SO4)3 + 3 NaOH → 2 Al(OH)3 + 3/2 Na2SO4

Alumnium sulfate decomposes when heated to 770 °C, to release sulfur trioxide vapors and leave behind alumina:

Al2(SO4)3 → Al2O3 + SO3

Aluminium sulfate slowly hydrolyzes in water to release diluted sulfuric acid.

Physical

Aluminium sulfate is an odorless, white hygroscopic crystalline compound, moderately soluble in water and insoluble in organic solvents. It has an acidic taste.

Aluminium sulfate is rarely encountered in the anhydrous form. Aluminium sulfate forms a number of different hydrates, the most common ones being the hexadecahydrate Al2(SO4)3·16H2O and octadecahydrate Al2(SO4)3·18H2O. A rarer form, the heptadecahydrate, written as [Al(H2O)6]2(SO4)3·5H2O, occurs naturally as the mineral alunogen.

Availability

Aluminium sulfate can be bought from various swimming pool and various home-improvement and gardening retailer stores, as flocculant tablets. The tablet always consists of the hydrated form.

Anhydrous or hydrated aluminium sulfate can be purchased from various chemical suppliers.

Preparation

Aluminium sulfate can be made by reacting sulfuric acid with aluminium oxide, hydroxide, halide or with hot aluminium metal.

2 Al(OH)3 + 3 H2SO4 → Al2(SO4)3 + 6 H2O
2 Al + 3 H2SO4 → Al2(SO4)3 + 3 H2

Projects

Handling

Safety

Aluminium sulfate has low toxicity compared to other compounds, but it may cause aluminium poisoning if ingested in large quantities. The salt is considered to be toxic to the reproductive system. The anhydrous form is irritant on skin and eye contact, and may irritate the lungs if inhaled. If released in the environment in large quantities, it will raise the level of aluminium in the soil as well as the soil acidity.

Aluminium sulfate slowly hydrolyzes in water to yield sulfuric acid which is highly corrosive. In one notorious case, a large amount of aluminium sulfate (20 tonnes) was accidentally dissolved in the Camelford water supply and the resulting sulfuric acid dissolved lead and copper from the city plumbing, causing short-term mass poisoning.

Storage

Anhydrous aluminium sulfate must be stored in airtight containers, while the hydrated forms can be stored in any container, just keep it away from moisture.

Disposal

Aluminium sulfate can be safely poured down the drain, though it's best to heavily dilute it first, to prevent a build-up of sulfuric acid.

Gallery

  • Aluminium sulfate flocculant tablet on a watch glass.

References

Relevant Sciencemadness threads

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