Final answer:
Accounting for the volume of molecules at low pressure involves primarily considering the attractions between molecules and ignoring molecular volume, as the correction for intermolecular attraction is more significant under these conditions.
Step-by-step explanation:
How do we account for the volume of molecules at low pressure? The correct approach is to ignore the molecular volume under these conditions. At low pressures, gas molecules have practically no attraction for one another due to the average distance between them, and they behave almost like particles of an ideal gas. However, attractions between gas molecules can serve to decrease the gas volume at constant pressure compared to an ideal gas with molecules that experience no attractive forces.
This reflects the fact that the correction for intermolecular attraction, often denoted by the parameter a in the van der Waals equation is more important than the correction for molecular volume, denoted by the parameter b, at low pressures. As the attractive force between molecules makes the gas more compressible than an ideal gas it is this correction for intermolecular attraction that we primarily consider at low pressures rather than increasing the pressure or decreasing the temperature as other potential factors influencing molecular volume.