An empty pressure vessel weighing 5 kg is placed in a water bath at 170 oC. It is slowly filled with n-Pentane while the vessel pressure is monitored. As soon as a jump in pressure is detected the filling operation is stopped and the vessel weight is measured and found to weigh 5.5 kg.
A valve on the pressure vessel is opened and 200 grams of the n-Pentane is removed
i) How much liquid and vapour will be present in the vessel?
ii) What is the vessel pressure?
A further 275 grams of n-pentane is then removed
iii) Determine the new vessel pressure
iv) What is the density of fluids in the vessel?
Assume ideal gas behaviour and isothermal conditions.
v) Comment on the validity of using these assumptions.
(the density of saturated liquid and vapour phases of n-pentane at 170 oC are 414.6 kg/m3 and 74.8 kg/m3)