Answer:
3 water molecules
Explanation:
The molar ratio between CuSO₄ and H₂O needs to be calculated.
The mass of water that was removed by heating is calculated, then converted to moles. The molecular weight of water is 18.02g/mol.
(8.97 g - 6.57 g) = 2.22 g H₂O
(2.22 g)/(18.02g/mol) = 0.1232 mol H₂O
The moles of anhydrous copper sulfate are calculated. The molecular weight is 159.609 g/mol
(6.57 g)/(159.609 g/mol) = 0.04116 mol CuSO₄
Now the molar ratio between CuSO₄ and H₂O can be calculated:
0.1232 mol H₂O ÷ 0.04116 mol CuSO₄ = 3 H₂O / CuSO₄