I just want to thank you both tremendously for your help with this. I spent a lot of time mulling over what you've said and it is pretty clear to me. It isn't very clear when looking at it at first, but it needs a little intuition and logic. Simply enough, the volume needs to remain constant...
Homework Statement
A rigid tank contains 5 lb of a two-phase, liquid-vapor mixture of H2O, initially at T = 260 F with a quality of 0.6. Heat transfer to the contents of the tank occurs until the temperature is T = 320 F. Show the process on a p-v diagram. Determine the mass of vapor, in lb...