Textbook Problem

Sulfur trioxide, SO₃, is produced in enormous quantities each year for use in the synthesis of sulfuric acid.

$\begin{array}{l}\text{S}\left(s\right)+{\text{O}}_{\text{2}}(g)\to {\text{SO}}_{\text{2}}(g)\hfill \\ 2{\text{SO}}_{\text{2}}\left(g\right)+{\text{O}}_{\text{2}}(g)\to 2{\text{SO}}_{\text{3}}\left(g\right)\hfill \end{array}$

What volume of O₂(g) at 350.°C and a pressure of 5.25 atm is needed to completely convert 5.00 g sulfur to sulfur trioxide?