Mass : 846.268 g
The mole is the number of particles contained in a substance
1 mol = 6.02.10²³
Moles can also be determined from the amount of substance mass and its molar mass
[tex]\tt mol=\dfrac{mass}{MW}[/tex]
mass of Al₂O₃ :
MW 101,96 g/mol
mass=mole x MW
[tex]\tt 8.3\times 101.96=846.268~g[/tex]