Saturated steam is condensed to saturated liquid in a piston–cylinder assembly at constant pressure. The 721-kg piston has a diameter of 15 cm and moves freely without friction during the process. The work transfer to the steam during this process is 56 kJ. The atmospheric pressure is 100 kPa, and the local gravitational acceleration is 9.80 m/s². Determine the mass of the H₂O.