How many oxygen atoms are contained in 2.74 g of Al2 (SO4) 3?

5.79 * 10^23 Oxygen atoms

Explanation:

Number of Oxygen atom in the compound = 4*3 = 12

Molar mass of Al2 (SO4) 3 = 342 g/mol.

No of mole = mass/molar mass = 2.74/342 = 8.01*10^-03 mole

2.74g of Al2 (SO4) 3 * 1 mole of Al2 (SO4) 3 / 342g of Al2 (SO4) 3 * 12 mole of Oxygen / 1mole of Al (SO4) 3 * 6.02*10^23 Oxygen atom / 1 mole of Oxygen

= 5.79*10^23 Oxygen atoms

either 12 or 24