A weightless piston separates an insulated horizontal cylindrical vessel into two closed chambers. The piston is in

Question:

A weightless piston separates an insulated horizontal cylindrical vessel into two closed chambers. The piston is in equilibrium with air on one side and H2O on the other side, each occupying a volume of 1 m3. If the temperature of both the chambers is 200oC, and the mass of H2O is 15 kg, determine the mass of air. Treat air as a perfect gas and H2O as a PC fluid.