For an assignment, I am graphing using the Van der Waals equation. I am meant to find graph PV (y-axis) over (P). However, I am not sure why. On the internet, most other graphs also use these axes. Why do you use PV though? I am getting a graph that generally similar to those on the internet. Mine goes into a bit of a trough at then it escalates upwards. Could someone please also tell me what the trough indicates? i was thinking it had something to do with liquefying but I am not sure if that is true.