'a' and 'b' are van der Waals constants for gases. Chlorine is more easily liquefied than ethane because :
a for Cl2 > a for C2H6 but b for Cl2 < b for C2H6
Vander Waals, constant a is due to force of attraction and b due to the infinite size of molecules. Thus, greater the value a and smaller the value b, larger the liquefaction.
|| 6.579 L2 bar mol-2
||0.05622 L bar mol-2
||5.562 L2 bar mol-2
||0.06380 L mol-1