Question

What is the $S.I$. unit of van der Waals’ constant $'a'$ ?

• A. $Pa\, L\,$ mol$^{-2}$
• B. $Pa\, m^{3} \,$mol$^{-2}$
• C. $Pa\, m^{6}\, mol^{-2}$
• D. $Pa\, m^{6}\, mol^{-1}$

Answer 1

Answer: (C)

As we know, $P =\frac{an^{2}}{V^{2}}$
$a = \frac{PV^{2}}{n^{2}}$
$= \frac{\left(Pa\right)\left(m^{3}\right)^{2}}{\left(mol\right)^{2}}$
$= Pa\, m^{6}\,$ mol $^{-2}$