calculate the number of molecules of oxygen required to react with 16.0g of sulfur in the following reaction S + O2 --------SO3

Answer 1

We need a balanced equation, and the one given is NOT balanced.

2S + 3O₂ ==> 2SO₃ .. balanced equation

We always work with moles in a balanced equation, so we will convert 16.0 g of S to moles:

16.0 g S x 1 mol S / 32.1 g = 0.4984 mols S

Using the mole ratio of the balanced equation, we now find moles of O₂ needed to react with S

0.4984 mols S x 3 mol O₂ / 2 mol S = 0.7477 moles O₂ needed

Finally, we convert moles of O₂ to molecules of O₂ using Avogadro's number:

0.7477 moles O₂ x 6.022x10²³ molecules / mole = 4.50x10²³ molecules of O₂