Answer
See the answer below.
Work Step by Step
Number of moles of water vapor:
$325\ g\div 18.015\ g/mol=18.04\ mol$
Van der Waals equation:
$\left[P+a\left(\dfrac nV\right)^2\right](V-bn)=nRT$
$(P+71.08\ atm)×4.45\ L=811.2\ L.atm$
$P=111.2\ atm$
Ideal gas:
$PV=nRT$
$P=162.3\ atm$
The term $a(n/V)^2$ has a much bigger influence in this difference.
