How many oxygen atoms are in 4.40g of Al2 (so4) 3?

First, we calculate the moles of Al₂ (SO₄) ₃:

moles = mass / Mr

= 4.4 / (27 x 2 + 3 x (32 + 16 x 4))

= 0.013 mole

Each mole of Al₂ (SO₄) ₃ contains 12 moles of Oxygen

Moles of oxygen = 12 x 0.013

= 0.156

Each mole of Oxygen contains 6.02 x 10²³ atoms

Atoms of Oxygen = 0.156 x 6.02 x 10²³

= 9.39 x 10²² atoms