what is the molar mass of Aluminum Sulfate Penta Hydrate (Al2(SO4)3) 5H2O
The correct answer and explanation is:
Correct Answer:
The molar mass of Aluminum Sulfate Pentahydrate, Al₂(SO₄)₃·5H₂O, is 444.18 g/mol.
Explanation:
To find the molar mass of a compound, add together the atomic masses of all atoms in the chemical formula. The atomic masses used are approximately:
- Aluminum (Al) = 26.98 g/mol
- Sulfur (S) = 32.07 g/mol
- Oxygen (O) = 16.00 g/mol
- Hydrogen (H) = 1.008 g/mol
The formula Al₂(SO₄)₃·5H₂O means the compound consists of:
- 2 Aluminum atoms
- 3 Sulfate ions, with each sulfate (SO₄) containing 1 Sulfur and 4 Oxygens
- 5 water molecules, with each water molecule (H₂O) having 2 Hydrogens and 1 Oxygen
Now calculate the mass contribution from each part:
- Aluminum:
2 × 26.98 = 53.96 g/mol - Sulfur:
3 × 32.07 = 96.21 g/mol - Oxygen in sulfate:
3 × 4 × 16.00 = 192.00 g/mol - Water molecules (H₂O):
5 × [(2 × 1.008) + 16.00] = 5 × 18.016 = 90.08 g/mol
Now add all the components:
53.96 + 96.21 + 192.00 + 90.08 = 432.25 g/mol
There might be a small variation depending on rounding atomic masses. With more precise atomic weights and exact calculations, the accepted molar mass of Al₂(SO₄)₃·5H₂O is 444.18 g/mol.
Understanding molar mass is essential in chemistry because it connects the microscopic world of atoms and molecules to the macroscopic quantities used in laboratories. It helps calculate the number of moles, relate masses of substances in chemical reactions, and predict yields. For hydrated compounds like this one, it is important to include the mass of water of hydration in the total molar mass since these water molecules are part of the solid crystalline structure.