Q. At low pressure, van der Waals’ equation is reduced to $\left\lbrack p + \frac{a}{V^{2}} \right\rbrack V = RT$. The compressibility factor can be given as
A) $1 + \frac{a}{RTV}$
B) $1 - \frac{RTV}{a}$
C) $1 + \frac{RTV}{a}$
D) $1 - \frac{a}{RTV}$
Explanation
(d)
$\left\lbrack p + \frac{a}{V^{2}} \right\rbrack V = RT$
$pV + \frac{a}{V} = RT$
$\frac{pV}{RT} + \frac{a}{VRT} = 1$
$\frac{pV}{RT} = \left( 1 - \frac{a}{VRT} \right) = Z$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.