The Properties of Gases and Liquids,

The ideal gas law provides one way to estimate the pressure exerted by a gas in a container. The law is

� =

���

�

More accurate estimates can be made with the van der Waals equation

���

� = −

� − ��

��²

�2

where the term �� is a correction for the volume of the molecules and the term

��2

�2 is a correction

for molecular attractions. The values of � and � depend on the type of gas. The gas constant is �, the

absolute temperature is �, the gas volume is �, and the number of gas molecules is indicated by �. If � = 1 [mol] of an ideal gas were confined to a volume of   =  22.41 [L] at 0°C (273.2 K), it would

J

exert a pressure of 1 atm. In these units, � = 0.08206 [

].

K⋅mol

3 3

For chlorine (Cl ), � = 0.6343 [Pa⋅m ] and � = 5.62 × 10⁻⁵ [ m ] (Reid et al, 1987). Compare the

2 mol2

mol