The ideal gas law provides one way to estimate the pressures and volumes of a gas in a container. The law is

P = RT/V̂

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

where the term b is a correction for the volume of the molecules and the term a/V̂² is a correction for molecular attractions. The values of a and b depend on the type of gas. The gas constant is R, the absolute temperature is T, and the gas specific volume is V̂ . If 1 mol of an ideal gas were conned to a volume of 22.41 L at 0°C (273.2 K), it would exert a pressure of 1 atm. In these units, R = 0.08206.

For chlorine (Cl₂), a = 6.49 and b = 0.0562. Compare the specific volume estimates V̂ given by the ideal gas law and the van der Waals equation for 1 mol of Cl₂ at 300 K and a pressure of 0.95 atm.

Transcribed Image Text:

RT a P = v - b V2