[livipivi88]

how would one determine the "b" values of the van der Waal equation?

the question asks:
 arrange the following according to expected values for "b" in van der Waals equation
-He, CO2, H2O, HF, SF6

[AWK]

From theoretical point of view
b=RTc/(8pc)
where
Tc means - critical temperature,
and
pc means - critical pressure

Constant b of the Van der Waals equation is approximately equal to 4 volumes of 1 mole of molecules. This method will fail for H2O and HF