One mole of a van der Waals gas with a=15.0 l^2 atm mol^−2 and b=0.015 l

Question

mol^−1 is expanded reversibly and isothermally from 1 atm to 0.5 atm at a temperature of
300 K. Calculate w for this process, and compare it with that required to expand an ideal
gas between the same volumes (calculating the volumes will be one of the trickiest parts of
this problem).