You decide that you want to make a sample of Al2O3 with a mass of 305.6 grams. How many grams of Al would you need?

Question

You decide that you want to make a sample of Al₂O₃ with a mass of 305.6 grams. How many grams of Al would you need?

 

 

Answer 1

The ratio of the atomic mass of the aluminum atoms to the molecular mass of aluminum oxide is given by

2 x atomic mass of Al divided by the molecular mass of Al2O3. The atomic masses of Al and O can be obtained from the periodic table.

2x 26.98 g/mole / 101.96 g/mole = 0.5292. This gives the grams of Al in one gram of Al2O3. If you multiply 0.5292 x 305.6 = 161.7 g Al, you get the grams of Al in 305.6 g Al2O3.