For a van der Waals gas, the change in entropy can be expressed as dT dS = Cv T + R -dv V-b A volume of 1 dm3 is partitioned by a wall into two equal parts, one containing 2.9 mol xenon (van der Waals parameters a = 4.250 dm6 bar mol^-22 and b = 0.0511 dm3 mol^-1), the other part being evacuated. Calculate the change in the entropy in J/K of xenon after the wall is removed and the gas undergoes a free expansion under isothermal conditions (T = 298.15 K). Ans in 4 SFs