Question

Calculate the pressure exerted by one mole of $CO_2$ gas at $273 \,K$ if the van der Waals' constant $a = 3.592 \,dm^6\, atm \,mol^{-2}$. Assume that the volume occupied by $CO_2$ molecules is negligible.

Answer 1

In case of negligible molecular volume, $b=0$ and van der Waals' equation reduces to
$\left(p+\frac{n^{2} a}{V^{2}}\right) V =n R T $
$\Rightarrow p =\frac{R T}{V}-\frac{a}{V^{2}} (n=1 \text { mole })$
$=\frac{0.082 \times 273}{22.4}-\frac{3.592}{(22.4)^{2}}=0.99\, atm$