The molecular weight of Aluminium sulfate octahydrate [Al₂(SO₄)₃.8H₂O] is 486.2770768.

Aluminium sulfate octahydrate [Al₂(SO₄)₃] (CAS Number: 18475-35-9) is an inorganic compound of three elements: Aluminium, Sulfur, and Oxygen. The octahydrate form of Aluminium sulfate [Al₂(SO₄)₃.8H₂O] also contains eight water molecules. The molecular weight of Aluminium sulfate octahydrate [Al₂(SO₄)₃.8H₂O] is 486.2770768 which can be calculated by adding up the total weight (atomic weight multiplied by their number) of all its elements and water molecules.

CALCULATION PROCEDURE: Aluminium sulfate octahydrate [Al₂(SO₄)₃.8H₂O] Molecular Weight Calculation

Step 1: Find out the chemical formula and determine constituent atoms and their number in an Aluminium sulfate octahydrate molecule.
From the chemical formula, you will know different atoms and their number in an Aluminium sulfate octahydrate molecule. The chemical formula of Aluminium sulfate octahydrate is [Al₂(SO₄)₃.8H₂O]. From the chemical formula, you can find that one molecule of Aluminium sulfate octahydrate consists of two Aluminium (Al) atoms, three Sulfur (S) atoms, twelve Oxygen (O) atoms, and eight water (H₂O) molecules.

Step 2: Find out the atomic weights of each atom (from the periodic table).

Atomic weight of Aluminium (Al): 26.9815384 (Ref: ciaaw-aluminium)
Atomic weight of Sulfur (S): 32.066 (Ref: Jlab-ele016)
Atomic weight of Oxygen (O): 15.9994 (Ref: Jlab-ele008)
Molecular weight of Water [H2O]: 18.0154

Step 3: Calculate the molecular weight of Aluminium sulfate octahydrate by adding the total weight of all atoms.

Number of Aluminium atoms in Aluminium sulfate octahydrate: 2
Atomic weight of Aluminium: 26.9815384
Total weight of Aluminium atoms in Aluminium sulfate octahydrate: 26.9815384 x 2 = 53.9630768

Number of Sulfur (S) atoms in Aluminium sulfate octahydrate: 3
Atomic weight of Sulfur: 32.066
Total weight of Sulfur atoms in Aluminium sulfate octahydrate: 32.066 x 3 = 96.198

Number of Oxygen (O) atoms in Aluminium sulfate octahydrate: 12
Atomic weight of Oxygen: 15.9994
Total weight of Oxygen atoms in Aluminium sulfate octahydrate: 15.9994 x 12 = 191.9928

Number of water (H₂O) molecules in Aluminium nitrate nonahydrate: 8
Molecular weight of water: 18.0154
Total weight of water in Aluminium nitrate nonahydrate: 18.0154 x 8 = 144.1232

Step 4: Calculate the molecular weight of Aluminium sulfate octahydrate by adding up the total weight of all atoms.

Molecular weight of Aluminium sulfate octahydrate: 53.9630768 (Aluminium) + 96.198 (Sulfur) + 191.9928 (Oxygen) + 144.1232 (Water) = 486.2770768

So the molecular weight of Aluminium sulfate octahydrate is 486.2770768.

Aluminium sulfate octahydrate [Al₂(SO₄)₃.8H₂O] Molecular Weight Calculation

REFERENCES:

• Ciaaw-aluminium: https://www.ciaaw.org/aluminium.htm
  
• Jlab-ele008: https://education.jlab.org/itselemental/ele008.html
• Jlab-ele016: https://education.jlab.org/itselemental/ele016.html
  

FURTHER READING

• Aluminum sulfate octahydrate from Sigma-Aldrich

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