1. Not finding help here? Sign up for a free 30min tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Drawing a PV Diagram

  1. Jan 9, 2011 #1
    1. The problem statement, all variables and given/known data

    One mole of an ideal gas at an inital tempreature of 300K and pressure of 4 atm is carried through the following reversible cycle:

    a) It expands isothermally until its volume is doubled.
    b) It is compressed to its original volume at constant pressure.
    c) It is compressed isothermally to a pressure of 4 atm.
    d) It expands at constant pressure to its original volume

    Make a plot of this cycle process on a PV diagram and calculate the work done by the gas per cycle.

    2. Relevant equations

    3. The attempt at a solution

    Okay so step a. means that while Vo goes to 2Vo the pressure doubles as well, yes? And step b means that the pressure is the same but the volume goes to Vo. And so then step C should mean that since P is returning to its initial, the gas returns to Vo too, right? But if that's true, then D doesn't make sense since it has already returned to Vo.

    Please help! Once I get the diagram correct, I'm just going to use the area to find the work done.
  2. jcsd
  3. Jan 9, 2011 #2


    User Avatar

    Staff: Mentor

    Take a look at the PV = nRT equation. If T is held constant (isothermal), how must P and V relate to each other?

    Again, take a look at PV = nRT. What's the current volume and pressure when step C begins? How do P and V vary when the compression (or expansion) is isothermal?
  4. Jan 9, 2011 #3
    Oh okay haha. . .P has to be half. . .

    Thank you :)
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Similar Discussions: Drawing a PV Diagram
  1. Pv=nrt and PV diagram (Replies: 2)

  2. PV Diagrams (Replies: 2)

  3. PV diagrams (Replies: 3)

  4. PV Diagram (Replies: 1)

  5. PV Diagram (Replies: 3)