Question

What is the significance of Vander Wall's constants?Out of $N_2$ and $N{H}_3$ which one will have (i) larger values of a (ii) larger value of b

Answer 1

The Van-der waal's equation of state approaches the ideal gas law $PV=nRT$ as the values of those constant approach zero. the constant ${}^{\prime }{a}^{\prime }$ provides a correction for the inter-molecules forces. Constant $b$ is a correction for the finite molecular size and its value is the volume of one mole of the atoms or molecules.

(ii) sice $N_2$ is the bigger of two molecules so it has greater value of $b$.

(i) $N{H}_3$ allows for relatively strong hydrogen bond while $N_2$. Only allows for relatively week London dispersion force, so $N{H}_3$ has greater value of $a$.