Q.
Van der Waals' equation for calculating the pressure of a non ideal gas is
$\left(p+\frac{a n^2}{V^2}\right)(V-n b)=n R T$
Van der Waals' suggested that the pressure exerted by an ideal gas, $p_{\text {ideal }}$ is related to the experimentally measured pressure, $p_{\text {real }}$ by the equation,
$p_{\text {ideal }}=p_{\text {real }}+\frac{a n^2}{V^2}$
Constant ' $a$ ' is measure of intermolecular interaction between gaseous molecules that gives rise to non-ideal behaviour depends on how frequently any two molecules approach each other closely. Another correction concerns the volume occupied by the gas molecules. In the ideal gas equation, $V$ represents the volume of the container. However each molecules does occupy a finite although small, intrinsic volume, so the effective volume of the gas becomes $(V-n b)$, where $n$ is the number of moles of the gas and $b$ is a constant
Which of the following represents a plot of compressibility factor $(Z) v s p$ at room temperature for He?
States of Matter
Solution: