Physical Chemistry Real gases Critical data and equations of state From van der waals equation RT b (8.14) . Division of the first equation in(8. 13)by the second yields 2a . RT □Vm-b=2mpme=3b(815) 3a C V-6 v m, c c Use of (8.15)in the first equation in(8.13)gives RT 2a 8a and 4b227b C 27Rb (8.16)Critical data and equations of state Division of the first equation in (8.13) by the second yields 2 m,c m,c c c V a V b RT P − − = From van der Waals equation: (8.14) 4 , 3 , 3 , 2 , 3 2 ( ) ( ) m c m c m c c m c c V a V a V b RT V b RT = − − Use of (8.15) in the first equation in (8.13) gives 3 2 , , m c m c V V −b = 2 3 and 27 2 4 b a b RTc = (8.16) Vm,c = 3b (8.15) Rb a Tc 27 8 = Physical Chemistry Real Gases