he specific heat of water is 4.2 kJ/kg°C. The heat needed to warm 8 kg of water from 20°C to 70°C is

Water enclosed in a rigid tank is heated from 120°C to 250°C. The pressure is high enough that the water remains subcooled (compressed) liquid during the process. Determine the thermal energy needed for the process (in kJ) if the mass of water is 8 kg. You can use water property tables or the incompressible substance assumption.

What is the new temperature (in K) of a closed gas system when it's volume is compressed from 5.6 L to 2.3 L and initial temperature was 455ﾟ K

One kg of superheated steam is at 400 kPa and 400°C. Heat is added to raise the temperature to 500°C. Find the amount of heat needed (kJ) if: (a) The volume of the steam is kept constant during the heating. (b) The steam is allowed to expand during the heating (e.g., in a piston/cylinder system) such that the pressure is constant. Hint: The steam is not an ideal gas under these conditions.