For CO2, van der Waals constants are a = 0.364 Pa m^6/mol^2 and b = 4.27 x 10^-5 m^3/mol. One mole at 300 K occupies 0.5 L. (a) Find the ideal pressure. (b) Find the van der Waals pressure. (c) Compute the critical temperature. Solution: V = 5 x 10^-4 m^3. (a) P_ideal = RT/V = (8.31)(300)/5x10^-4 = 4.99 x 10^6 Pa ~ 49.9 bar. (b) P = RT/(V-b) - a/V^2 = 2493/(5x10^-4 - 4.27x10^-5) - 0.364/(2.5x10^-7) = 2493/4.573x10^-4 - 1.456x10^6 = 5.45x10^6 - 1.456x10^6 = 3.99 x 10^6 Pa ~ 39.9 bar - attractions lower it notably. (c) Tc = 8a/(27Rb) = 8(0.364)/(27 x 8.31 x 4.27x10^-5) = 2.912/9.58x10^-3 = 304 K.