States of Matter - Result Question 71
71. Calculate the pressure exerted by one mole of $CO _2$ gas at $273 K$ if the van der Waals’ constant $a=3.592 {dm}^{6} {\hspace {1mm} atm}$ $mol^{-2}$. Assume that the volume occupied by $CO _2$ molecules is negligible.
(2000)
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Answer:
Correct Answer: 71. $(0.99 {~\hspace {1mm} atm})$
Solution:
In case of negligible molecular volume, $b=0$ and van der Waals’ equation reduces to
$\left(p+\dfrac{n^{2} a}{V^{2}}\right) V =n R T $
$\Rightarrow \quad p =\dfrac{R T}{V}-\dfrac{a}{V^{2}} \quad(n=1 \text { mole }) $
$ =\dfrac{0.082 \times 273}{22.4}-\dfrac{3.592}{(22.4)^{2}}=0.99 \hspace {1mm} atm$
BETA
