Final answer:
To find the number of moles of Al2O3 in 6.83 g, divide the mass by the molar mass of Al2O3, which is 101.96 g/mol. This results in approximately 0.067 moles of Al2O3.
Step-by-step explanation:
To calculate the number of moles of aluminum oxide (Al2O3) in 6.83 g of Al2O3, we use the molar mass of Al2O3. The molar mass is calculated by adding the molar masses of 2 atoms of aluminum (Al) and 3 atoms of oxygen (O). From the periodic table, the molar mass of Al is approximately 26.98 g/mol and that of O is approximately 16.00 g/mol, thus:
- Molar mass of Al2O3 = (2 × 26.98 g/mol) + (3 × 16.00 g/mol) = 101.96 g/mol.
- Using the formula:
Number of moles = mass (g) ÷ molar mass (g/mol)
We get:
Number of moles of Al2O3 = 6.83 g ÷ 101.96 g/mol = 0.067 moles (rounded to three significant figures).
Therefore, there are approximately 0.067 moles of Al2O3 in a 6.83 g sample.