A .5 m^3 tank contains ammonia initially at 40 C and 8 bar. A leak develops, and refrigerant flows out of the tank at a constant mass flow rate of .04 kg/s. The process occurs slowly enough that heat transfer from the surroundings maintains a constant temperature in the tank. Determine the time, in second, at which half of the mass has leaked out and the pressure in the tank at that time in bar.