$8-38.$ Use the expression for $ln$ in reduced form given in Problem $8-37$ along with the RedlichKwong equation in reduced form $($Example $2-7)$ to plot $ln$ versus $P_R$ for $T_R=1\mathrm{.}00$ and $2\mathrm{.}00$ and compare your results with those you obtained in Problem $8-35$ for the van der Waals equation.