what is the maximum mass of sulfur trioxide that can be obtained by reacting 72 dm^3 of sulfur dioxide with excess oxygen?

Answer 1

Assuming conditions of STP...

72 L SO₂ x 1 mole/22.4 L = 3.21 moles SO₂

2SO₂ + O₂ ==> 2SO₃

3.21 moles SO₂ x 2 moles SO₃/2 moles SO₂ x 80 g/mole = 257 g SO₃