•Real gases have real volume. –Gas particles are notpoints of mass, but have volumes determined by the sizes of their atoms and the bonds between them. •Real gases do experience attractive and repulsive forces between their particles. •Real gases deviate most from ideal behavior at low temperatureand high pressure.
5-65 Figure 5.23 Deviations from ideal behavior with increasing external pressure.
5-66 Figure 5.24 The effect of interparticle attractions on measured gas pressure.
5-67 Figure 5.25 The effect of particle volume on measured gas volume.
5-68 The van der Waals equation•The van der Waals equation adjusts the ideal gas law to take into account – the real volume of the gas particles and – the effect of interparticle attractions. (P+n2aV2)(V!nb)=nRTVan der Waals equation for n moles of a real gas The constant arelates to factors that influence the attraction between particles. The constant brelates to particle volume.
5-69 0.034 0.211 1.35 2.32 4.19 0.244 1.39 1.36 6.49 2.25 1.45 3.59 4.17 5.46 He Ne Ar Kr Xe H2N2O2Cl2 CH4 CO CO2 NH3H2O 0.0237 0.0171 0.0322 0.0398 0.0511 0.0266 0.0391 0.0318 0.0562 0.0428 0.0395 0.0427 0.0371 0.0305 Gas a atm·L2mol2b L mol Table 5.4Van der Waals Constants for Some Common Gases