4AlCl3 + 3O2 → 2Al2O3 + 6Cl2 How many moles of Cl2 are needed to make 75.5 grams of O2?

Answer 1

grams O₂ → mol O₂ → mol Cl₂

Convert grams oxygen to moles with molar mass:

1 mol O₂=32.00 g/mol (add up from ptable)

mol O₂=75.5/32.00=2.359 mol O₂

Convert moles oxygen to moles chlorine with the coefficients:

3 mol O₂ = 6 mol Cl₂

2.359 mol O₂ (6 mol Cl2 / 3 mol O2) = 4.719 mol Cl₂

Round to 3 sig figs

4.719

=4.72 mol Cl₂