1. The problem statement, all variables and given/known data The problem is a long one. Basically we have to use Maxwell's Equal Area Construction. "With Mathcad, find Psat and the corresponding saturation volumes at T=400K for n-hexane based on the van der Waals' equation of state. Furthermore, turn Psat into a function of temperature T, i.e., define Psat(T) and identify the temperature range within which your Psat function works. Plot Psat versus T" 2. Relevant equations Work done through a hypothetical reversible path under "dome" = Work done by expanding at constant Psat across "dome" ∫P(V)*dV = Psat*(Vv-Vl)dV Equivalently, two areas enclosed by Psat and P(V) are equal; thus, the name "Maxwell's equal areas rule". ∫(Psat-P(V))*dV = ∫(P(V)-Psat)*dV The integrals are from Vl to Vm, and Vm to Vv, respectively 3. The attempt at a solution So this is all done with MathCad. First I defined all the parameters for Van der Waals (what Tc, Pc, a, and b were... and eventually what the filled in Van der Waals equation was). I have a couple questions... Should I use Antoine Equation to find Psat? I did that already and found what Psat was at there temperature specified. Secondly, I think I have to use the "find" function in MathCad. I'm definitely doing something wrong. I defined the second integral in the given equations and use a Bullian equal sign. I set up a matrix where each solution was a row, and then did find(Vv, Vl) to no avail. Can someone please shed some light?