Three kg of water in a piston-cylinder apparatus is initially in the saturated liquid state at 0.6 MPa. Energy is added slowly to the water as heat and the piston moves in such a way that the pressure remains constant. How much energy must be added as heat to bring the water to the saturated vapor state? Note: Under this constant pressure condition, the work done by the expanding water on the environment is given by
W =mP(V2 - V1 )
where m is the mass of water, P is pressure and V is the specific volume of water.