Determine the mass of oxygen in a 7.2-g sample of Al2(SO4)3

1 answer

mols Al2(SO4)3 = grams/molar mass = ?
There are 12 O atoms per 1 mol Al2(SO4)3 so there are 12 x mols Al2(SO4)3 there.

Convert mols O to grams O. g = mols x 16 = ?

I assume the question means grams O (atoms) and not O2 (molecules).