Answer: ≈ 708 ( to 3 s.f.)
Working Out:
First we have to establish a balanced chemical equation that defines the reaction
4 Al + 3 O₂ → 2 Al₂O₃
Now, mole = mass ÷ molar mass
∴ If the mass of Al in the reaction = 375 g
then the # of moles of Al = 375 g ÷ 27 g/mol
= 13.889 mol
Also, the mole ratio between Al and Al₂O₃ is 2 : 1 (4 : 2).
As such if moles of Al = 13.889 mol
then # of moles of Al₂O₃ = 13.889 mol ÷ 2
= 6.944 mol
Since mass = mole × molar mass
Then mass of Al₂O₃ = 6.944 mol × ((27 × 2) + (16 × 3)) g/mol
= 6.944 mol × 102 g/mol
= 708.288 g
