I posted this in the engineer / comp science thread, but I've had no one reply or help. I really could use some guidance and I don't know where else to post. 1. The problem statement, all variables and given/known data I am tasked to create a PV Diagram of a Carnot Engine Cycle. I must find pressure, volume, Q, W, ΔU, and ΔS on all four points. This is what has been given to me by my teacher: https://lh6.googleusercontent.com/LupjMh6SJxv2M4loxPxaSIMEaU6wtMeMfz0_jjY6dgyyEewHwdgzplahrV0Xidfkjpn4dfu3h0wcjoc=w1920-h1021 TCold = 300 K THot = 1700 K pc = 1.01*105 Pa vc = 0.01 m3 Qa to b = 300 J γ (gamma) = 1.40 2. Relevant equations (1) p1v1=p2v2 (2) W=nRT ln(V2/V1) (3) p1v1γ=p2v2γ (4) W= p1v1-p2v2 / (γ-1) (5) T1V1(γ-1) = T2V2(γ-1) (6) W = nRT ln(V2/V1) (7) pv = nRT 3. The attempt at a solution Using the above equations I managed to get point b's pressure and volume. What I got for point b: vb = 0.028 m3 pb = 2.389*104 Pa First, I used the gas law equation (7) to get moles. This came out to n = 0.405 moles. Then, I used equation (5) to get volume, solving for Vb(y-1). I then used equation (3) to get pressure, solving for pb. I then got W = -852.7 J for the path b to c using equation (4). This seems kind of odd to me and I'm not sure if its correct because it's doing more work than the amount of heat it is providing. I assume Qa to b = is QH ? It seems so low though. I'm trying to figure out how am I going to get points d and a without knowing pressure or volume on those points. A class mate had suggested I used equation (5) for a to b and c to d, but those paths are isothermal. Isn't equation (5) adiabatic only? I don't know if I can even use the gas law because I'd need pressure or volume and I don't have that. There is also the idea that I have to use equation (6) and solve for volume that way. The problem is I don't know where to start. I'm a little rusty on my calculus (it's been about 4 years). I tried to break it down to W = nRT(ln (V2) - ln (V1))= nRT( 1/V2 - 1/V1), but this doesn't seem to help and I may have done it wrong. I'd be grateful for any kind of help.