What is the molar mass of alumina, Al2O3? The atomic weight of aluminium is 26.98 and the atomic weight of oxygen is 16.00.
42.98 g/mol
48.00 g/mol
149.96 g/mol
101.96 g/mol
The Correct Answer and Explanation is:
To determine the molar mass of alumina (Al₂O₃), we need to calculate the total mass of all the atoms in one mole of the compound.
Step-by-Step Calculation:
Chemical formula of alumina: Al₂O₃
This means the compound contains:
- 2 atoms of aluminum (Al)
- 3 atoms of oxygen (O)
Atomic weights (given):
- Aluminum (Al) = 26.98 g/mol
- Oxygen (O) = 16.00 g/mol
Now, calculate the molar mass: Molar mass of Al2O3=(2×26.98)+(3×16.00)\text{Molar mass of Al}_2\text{O}_3 = (2 \times 26.98) + (3 \times 16.00) =53.96+48.00=101.96 g/mol= 53.96 + 48.00 = \boxed{101.96 \, \text{g/mol}}
Explanation:
The molar mass of a compound refers to the mass of one mole of its molecules. A mole is a standard scientific unit for measuring large quantities of very small entities such as atoms or molecules. One mole of any substance contains Avogadro’s number of particles, which is 6.022×10236.022 \times 10^{23}.
Alumina, or aluminum oxide (Al₂O₃), is a white crystalline compound commonly found in nature as the mineral corundum. It is a significant raw material in the production of aluminum metal and also has applications in ceramics and refractories due to its hardness and high melting point.
When calculating the molar mass of a compound, each element’s atomic weight is multiplied by the number of times that element appears in the formula, and the products are then added together.
In this case:
- Two aluminum atoms contribute 2×26.98=53.962 \times 26.98 = 53.96 g/mol.
- Three oxygen atoms contribute 3×16.00=48.003 \times 16.00 = 48.00 g/mol.
Adding these gives a total molar mass of 101.96 g/mol, which is the correct and final answer.