Avertical piston-cylinder device contains water and is being heated on top of a range. during the process, 65 btu of heat is transferred to the water, and heat losses from the side walls amount to 8 btu. the piston rises as a result of evaporation, and 5 btu of work is done by the vapor. determine the change in the energy of the water for this process.

Asteam is contained in a rigid tank with a volume of 1 m3. initially, the pressure and temperature are 7 bar and 500 oc, respectively. the temperature drops due to cooling process. determine: (1) the temperature at which condensation begins in °c, (2) the fraction of the total mass that has condensed when the pressure decreased to 0.5 bar. (3) the volume in m3 occupied by saturated liquid at the final state?