A cylinder with a piston contains 0.3 kg of water at 100 degrees C. What is the change in internal energy of the water when it is converted to steam at 100 degrees C at a constant pressure of 1 atm? The density of water is 1000 kg/m^3 and that of steam is 0.6 kg/m^3. The latent heat of vaporization of water is 2.26E+06 J/kg.