Question

The values of Van der Waals constant 'a' for the gases $O_2$, $N_2$, $N{H}_3$ and $C{H}_4$ are 1.360, 1.390, 4.170 and 2.253 L atm mol${}^{-2}$ respectively. The gas which can most easily be liquefied is:

• A. $O_2$
• B. $N_2$
• C. ${NH}_3$
• D. ${CH}_4$

Answer 1

The correct option is C ${NH}_3$

$[P+\frac{a{n}^2}{V^2}](V-nb)=nRT$

The van der Waals constant $a$ is used in pressure correction, and its value depends upon the intermolecular forces between the gas molecules. The larger the value of $a$ for a gas, the more easily that gas can be liquefied.

So according to value of a, $N{H}_3$ liquifies easily.