At a subcritical temperature, the branch of the PengRobinson equation of state for V > b exhibits a van der Waals loop. However, there is also interesting behavior of the equation in the ranges V < b and V < 0, though these regions do not have any physical meaning. At supercritical temperatures the van der Waals loop disappears, but much of the structure in the V < 0 region remains. Establish this by drawing a P-V plot for n-butane at temperatures of 0.6 T_c, 0.8 T_c, 1.0 T_c, 1.5 T_c, and 5 T_c for all values of V .