Question

Find the heat liberated by the water stored In a tank of capacity 0.5 m^3. The temperature of the water in the tank is 20°C, and room temperature is 5°C.

Answer 1

The room temperature = 5 ⁰C

The air in the room and the walls and other objects will be heated up taking the heat from the hot water in the tank.  The temperature of the water in the tank comes down to 5°C.

   heat liberated =  mass * specific heat capacity * temperature difference
                       = 0.5 m³ * 1000 kg/m³  * 4.18 kJ/°C/kg  * (20° - 5°C)
                   = 31, 350 kJ